Abstract:
The present document describes an assembly for interfacing an existing harness connector of an installed wiring harness to a test module, the assembly comprising: a harness-specific connector for connecting to the existing harness connector; a test box connector module connected to the harness-specific connector and for connecting to a test module, the test box connector module comprising a key which is unique to the test box connector module and which is used to identify the test box connector module when connected to the test module. There is described a method for identifying a test box connector module used in testing an installed wiring harness comprising an existing harness connector, the method comprising: connecting the test box connector module to a test module; detecting a key which is unique to the test box connector module thereby determining the identity of the test box connector module; sending the identity of the test box connector module to a user interface.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority under 35USC§120 of allowed US non-provisional patent application Ser. No. 10/932,309, filed Sep. 2, 2004, bearing the same title, the specification of which is hereby incorporated by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The invention relates to a system and method for testing and repairing installed wiring harnesses. 
       BACKGROUND OF THE INVENTION 
       [0003]    An electrical wiring harness typically comprises a bundle of individual connector wires of varying gauges, impedances and types, all arranged and distributed at different locations within an installation, such as a transport vehicle. Such wiring harnesses are usually bound together in order to facilitate the installation, repair and maintenance of the wires. The transport vehicle industry, especially the aviation and the automobile industries, makes extensive use of such wiring assemblies. 
         [0004]    In the aircraft industry, wiring harnesses are used to interconnect the various components and subassemblies located within an aircraft. The number of possible electrical interconnections within a harness grows exponentially with the number of wires and connectors. Therefore, electrical problems within a harness are incredibly hard to identify and locate, especially for already installed harnesses. 
         [0005]    In the prior art, a typical method of testing an installed harness is by using a ringing cable. Unfortunately, such a method is inconvenient as it presents numerous drawbacks. Such a method requires that a plurality of operators be deployed at various connection points along the wiring harness, their locations being chosen in accordance with electrical schematics, and the operators communicating and coordinating testing procedures through walkie-talkies. With prior art methods, the operators have to ring cables, one at a time, which requires many operators for complex or multiple connections. 
         [0006]    Another prior art method of testing a wiring harness involves connecting devices to the installed harness via cables and performing the testing. However, such a method requires installation of interface cables and other components from the system for testing. Additionally, it requires the deployment of many operators and the use of maintenance manuals, which makes the process time-consuming, expensive and prone to human error. 
         [0007]    Another problem in the prior art is that of keeping accurate records of the results of testing and maintenance procedures. Currently, such information is manually recorded by operators into wiring diagrams and/or work orders, a practice which is prone to errors and omissions and which does not allow for analysis of the data recorded over time. 
         [0008]    Testing devices such as TDR testing units have been developed to test wiring harnesses, one wire at a time. Unfortunately, prior art TDR methods do not allow for performing testing on multiple wires at a time, which proves to be time consuming and does not allow for gathering complete and accurate information regarding the wires. 
         [0009]    There exists therefore a need for a system and a method for testing an installed wiring harness, which is time and cost efficient. 
         [0010]    Additionally, there exists a need for a system and method for testing an installed wiring harness, which is not prone to human error. 
         [0011]    Furthermore, there exists a need for adequate documentation following testing procedures. 
         [0012]    According to an embodiment, there is provided a method for testing an installed wiring harness, comprising: providing a signal source testing module at a first connection point in the wiring harness; providing a measurement termination testing module at a second connection point in the wiring harness; providing a central management module for controlling the testing modules to coordinate the testing modules to send testing signals from the first connection point to the second connection point, after disconnecting electrical power between the connection points, for performing tests and recording test measurements of the installed wiring harness; and the signal source testing module and measurement termination testing module for sending the test measurements to the management module. 
         [0013]    According to an embodiment, there is provided a system for offline testing of an installed wiring harness, comprising: at least a first and a second testing module, having: a communication module for receiving test specifications and for sending test measurements; testing equipment for generating the test measurements from the test specifications; each of the first and second testing modules being adapted for connection at a connection point in the wiring harness; a central network management module, having: a communication module for providing the test specifications to the testing modules and for receiving the test measurements; and a test management module for controlling the testing modules. 
       SUMMARY OF THE INVENTION 
       [0014]    Accordingly, an object of the present invention is to provide a system and method for testing an installed wiring harness, which allows automated testing of multiple lines simultaneously, thereby reducing the time and the cost of the testing procedure. 
         [0015]    It is another object of the present invention to provide a system and method for testing an installed wiring harness, which is automated, thereby eliminating human error. 
         [0016]    It is yet another object of the present invention to provide a system and method for testing an installed wiring harness which allows to produce automatically standardized maintenance reports and electronic logbook. 
         [0017]    According to an aspect of the invention, there is provided a method for testing an installed wiring harness, comprising: providing a signal source testing module at a first connection point in the wiring harness; providing a measurement termination testing module at a second connection point in the wiring harness; providing a central management module for controlling the testing modules to coordinate the testing modules to send testing signals from the first connection point to the second connection point, after disconnecting electrical power between the connection points, for performing tests and recording test measurements of the installed wiring harness; and the signal source testing module and measurement termination testing module for sending the test measurements to the management module. 
         [0018]    According to another aspect of the invention, there is provided a system for offline testing of an installed wiring harness, comprising: at least a first and a second testing module, having: a communication module for receiving test specifications and for sending test measurements; testing equipment for generating the test measurements from the test specifications; each of the first and second testing modules being adapted for connection at a connection point in the wiring harness; a central network management module, having: a communication module for providing the test specifications to the testing modules and for receiving the test measurements; and a test management module for controlling the testing modules. 
         [0019]    According an embodiment, there is provided an assembly for interfacing an existing harness connector of an installed wiring harness to a test module, the assembly comprising: a harness-specific connector for connecting to the existing harness connector; a test box connector module connected to the harness-specific connector and for connecting to a test module, the test box connector module comprising a key which is unique to the test box connector module and which is used to identify the test box connector module when connected to the test module. 
         [0020]    According an embodiment, there is provided a method for identifying a test box connector module used in testing an installed wiring harness comprising an existing harness connector, the method comprising: connecting the test box connector module to a test module; detecting a key which is unique to the test box connector module thereby determining the identity of the test box connector module; sending the identity of the test box connector module to a user interface. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    Further features and advantages of the present invention will become apparent from the following detailed description, taken in combination with the appended drawings, in which: 
           [0022]      FIG. 1  is a block diagram of an automated harness scanner system according to a preferred embodiment of the present invention; 
           [0023]      FIG. 2  is a block diagram of a test module connected to a wiring harness according to a preferred embodiment of the present invention; 
           [0024]      FIG. 3  is a block diagram of an analysis module according to a preferred embodiment of the present invention; 
           [0025]      FIG. 4  is a diagram of an automated harness scanner system having a central management system and distributed test modules according to a preferred embodiment of the present invention. 
           [0026]      FIG. 5  is a schematic diagram of two test modules installed in a wiring harness, testing a wire showing a break point. 
           [0027]      FIG. 6  is a graph of an exemplary TDR return signal obtained when applying a pulse input signal to a wire without shielding defects. 
           [0028]      FIG. 7  is a graph of an exemplary TDR return signal obtained when applying a pulse input signal to a wire with shielding defects. 
       
    
    
       [0029]    It will be noted that throughout the appended drawings, like features are identified by like reference numerals. 
       DETAILED DESCRIPTION 
       [0030]    As illustrated in  FIG. 4 , the present invention is a fully portable automated test system allowing verification of any type of installed wiring harness  27  using a new open platform architecture for the transport industry. Even though the testing system shown in  FIG. 4  is used for testing a wiring harness installed in a plane, the testing system could also be used for testing a wiring harness installed in any other installation for which periodical testing, diagnosis and maintenance is required. Such other installations might include, but are not limited to, boats, ships, trains, cars, etc. 
         [0031]    In the preferred embodiment of the present invention, the automated testing system is a distributed network, comprising a plurality of test modules  31  which are connected to the wiring harness  27  at the location of existing harness connectors  29 . The test modules  31  are in communication with a central Network Management System (NMS)  10 , from which the test modules  31  receive information regarding the testing of the wiring harness  27  and to which they send back test results following completion of testing. 
         [0032]    In one embodiment of the present invention the test modules  31  communicate with the NMS  10  over a wireless connection, using a protocol such as TDMA in order to support a large number of test modules  31 , such as in the case of testing a wiring harness  27  having a plurality of connectors at different locations. It is however within the scope of the present invention that the test modules  31  send and receive information through a cable connection. 
         [0033]    The NMS  10  is preferably a computer system having input means, display means and storage means and/or other components well-known to those skilled in the art. In the preferred embodiment of the present invention, the computer system includes, for example, a central processing unit (CPU), random access memory (RAM), read-only memory (ROM), as well as various peripheral devices, each connected to a local bus system. Also coupled to the local bus system are a mass storage device, a keyboard, a pointing device (mouse, trackball, touchpad, etc.), a communication device, etc. The communication device is any device allowing the computer system  11  to communicate with a remotely located device over a communication link, such as a telephone modem, cable modem, ISDN, wireless, etc. 
         [0034]    Now, with respect to  FIG. 1 , the preferred architecture of the NMS  10  according to the present invention will be described. The data management module  13  contains all the software required to interface with external storage module  14  as well as the NMS data storage  12 . The external storage  14  contains an electronic logbook unique to each transport vehicle, which contains all transport vehicle electrical information, wiring harness signature and past test results. The NMS storage  12  contains all the historical data, statistical variation data and modeling information for a particular wiring harness  27 . The data management module  13  is a software configuration management tool allowing to control and validate information to be stored in the transport vehicle electronic logbook and NMS storage  12 . Compression data algorithms are preferably used for storing and managing data in an efficient manner on the storage units  12 ,  14 . 
         [0035]    The data management module  13  receives data from a signature builder module  11 . The signature builder module  11  generates a wiring harness signature for a given transport vehicle harness  27  based on manufacturing specs. The module  11  generates a listing of the transport vehicle wiring harness basic characteristics and properties in terms of material, gauge, length, resistance, impedance, tolerance, conductivity, cross-talk, insulation and many more. The wiring harness signature may be uploaded by transferring raw data from the transport vehicle manufacturer database. This can be achieved by directly accessing the database or by providing the manufacturing specs on a CD-ROM to the system. Alternatively, the wiring harness signature can be generated by connecting the testing system to the transport vehicle wiring harness  27 . In the case the wiring harness signature is generated, it is the artificial intelligence module  15  that provides it to the data management module  13 . 
         [0036]    The artificial intelligence module  15  is a self-learning tool for optimization which enables modification of its own program based on its learning experience. The artificial intelligence module  15  provides diagnosis and recommendations based on historical data, models and test data results received from the test modules  31  through the communication module  21 . 
         [0037]    As shown in  FIG. 3 , in the preferred embodiment of the present invention, the artificial intelligence module  15  includes a signature update module  49  and an analysis module  51 . The signature update module  49  manages historical data, statistical data and signature updates from test results received from test modules  31 . If a signature is not available for a given installed wiring harness  27 , the signature module  49  allows building a signature by performing a series of test and gathering a set of electrical characteristics of the wiring harness  27 . When the signature update module  49  receives the test results from all the test modules  31  and no signature is available for a specific transport vehicle wiring harness  27 , then it will generate and store the harness signature. The signature update module  49  will propose signature changes to the Data Management module  13  by requesting the storage of all information previously detected and measured such as connectivity table, Netlist, which describes the connectivity of the wiring harness, or the wire mapping between each connection point, and includes each of the wires&#39; physical attributes, and all electrical characteristics measured and provided by test modules  31  in the format of a harness signature. 
         [0038]    The electrical harness signature contains information that is unique for each wire of the wiring harness  27 . The harness signature for each wire describes the electrical characteristics of that particular wire. In the preferred embodiment of the present invention, the harness signature is a multiple-dimensional array. Table 1 illustrates an exemplary harness signature structure: 
         [0000]    
       
         
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 VARIABLE 
                 TYPE 
               
               
                   
               
             
             
               
                 CONNECTION 
                 DYNAMIC MULTIPLE DIMENSION 
               
               
                   
                 ARRAY 
               
               
                 WIRE SPECIFICATION 
                 ARRAY 
               
               
                 DC MEASUREMENTS 
                 ARRAY 
               
               
                 AC MEASUREMENTS 
                 ARRAY 
               
               
                 SWR MEASUREMENTS 
                 ARRAY 
               
               
                 SWR RETURN SIGNALS 
                 DYNAMIC MULTIPLE DIMENSION 
               
               
                   
                 ARRAY 
               
               
                 TDR RETURN SIGNALS 
                 DYNAMIC MULTIPLE DIMENSION 
               
               
                   
                 ARRAY 
               
               
                 SPECTRUM IMPEDANCE 
                 DYNAMIC MULTIPLE DIMENSION 
               
               
                 MEASUREMENTS 
                 ARRAY 
               
               
                   
               
             
          
         
       
     
         [0039]    The connection variable is a dynamic, multiple-dimension array containing information in wire connection to other points in the wiring harness  27 . The wire specification variable is an array of manufacturer specifications, such as conductor material, shielding material, gauge, insulation, conductance, dilatation, etc. 
         [0040]    The “DC measurements” variable is preferably an array containing measured voltage and current values, as well as resistance and conductance values. 
         [0041]    The “AC measurements” variable is another array containing voltage and current values measured for different AC input signals. In the preferred embodiment of the present invention, sinusoidal signals of 1 kHz, 100 kHz and 1 MHz of 1 V peak-to-peak are used as input signals. The AC measurements include values of calculated impedance. 
         [0042]    The “SWR measurements” variable is an array containing time delay values for the return signal from an input sinusoidal signal. In the preferred embodiment of the present invention, sinusoidal signals of 1 kHz, 100 kHz and 1 MHz of 1 V peak-to-peak are used as input signals. The SWR measurements also include values of calculated conductor length or break point based on the Doppler equations. 
         [0043]    The “SWR return signals” variable is a dynamic multiple dimension array containing all sample data points for the return signal from an input sinusoidal signal. 
         [0044]    The “TDR return signals” variable is a dynamic multiple dimension array containing all sample data points for the return signal from an input pulse signal, sent at various frequencies, preferably at 1 KHz, 100 KHz and 1 MHz. 
         [0045]    The “Spectrum impedance measurements” variable is another dynamic multiple dimension array containing measured impedance values, in polar and vector form, for a 1-V peak-to-peak input sinusoidal signal. Preferably, the input sinusoidal is varying over a frequency spectrum from 1 KHz to 1 MHz in steps of 50 KHz. This array contains as well calculated Nyquist plot data over the 1 KHz to 1 MHz spectrum. 
         [0046]    The artificial intelligence module  15  also includes an analysis module, which is a self-learning module with the capability to give a diagnosis and recommendation on a transport vehicle wiring harness  27 . The analysis module  51  receives test results from the test modules  31 . Also, this module  51  receives the harness signature and statistical data from the signature update module  49 . Then, this module retrieves the wiring harness model from the NMS storage  12  through the data management module  13  to perform a diagnosis and recommendation. The diagnosis/recommendation is sent to the test management module  17 . Finally, this module will decide to send or not a new harness model analysis to the data management module  13  based on the new learning experience. 
         [0047]    The test management module  17  sends the test specification regarding the measurements to be performed by each of the test modules of the system. The test management module  17  is also in communication with an analysis module  15  for receiving either a diagnosis or recommendations and a harness signature for the wiring harness  27 . The test management module can also provide this information for the operator through a report module  23  or a user interface module  25 . 
         [0048]    The test management module  17  communicates with the network of distributed test modules  31  through a communication module  21 . In the preferred embodiment of the present invention, the communication module is a transmitter (emitter/receiver) communicating to each test module  31  using a STAR configuration. The module  21  is a HUB assigning and managing all frequencies, signal strength, power and time slots in the testing system. 
         [0049]    The report module  23  is an automated tool used to format special printouts, such as metallic labels, cable prints, as well as parts and inventory numbers. The report module  23  may also be used as a tool for generating Quality Assurance and maintenance reports including the test results collected during a given test session or past test results. The report module  23  receives all the information required from the test management module  17 . 
         [0050]    The user interface module  25  controls all the man machine interfaces required for data input and output. It can display on-line schematic diagrams, Netlists and any wire characteristics and properties, as well as the transport vehicle electronic logbook. 
         [0051]    The maintenance management module  19  is an assistance tool to any operator using the automated testing system. It provides a step-by-step procedure to guide the operator in testing a transport vehicle wiring harness  27  for a specific vehicle sub-system. The maintenance management module  19 , through the user interface module  25 , prompts the operator by asking which sub-system to test and provides the user with information regarding the number of test modules required, where to connect them and their location within the transport vehicle. 
         [0052]    In a first step, the operator would identify a faulty subsystem within the wiring harness  27 , by using on-board computers with built-in self-test (BITES) capabilities. If the subsystem cannot be identified by the BITES, the operator will review indicators, sensors information as well as the pilot&#39;s flight book to identify the subsystem. 
         [0053]    The operator will then load a specific CD-ROM aircraft logbook in the computer, which contains all wiring harness information for the particular aircraft. The system first prompts the operator to enter the aircraft sub-system to test. Then, the HS2000 maintenance program replies with the number of test modules  31  and test box connectors modules required to perform the test as well as the locations of aircraft connectors to be tested. 
         [0054]    The operator then disconnects the aircraft-specific harness connector  29  from the aircraft wiring harness  27  and connects the test module  31  with the appropriate connector module  33 . Then, the operator powers on the test module  31 , at which time the test module is automatically assigned a system ID by the NMS. The system ID contains a time slot, frequency and signal strength according to the TDMA protocol. This procedure is repeated for all test modules  31  to be connected. 
         [0055]    After having installed all test modules  31 , the operator then returns to the computer to start the testing routine. If any problems occurred during installation, the system will notify the operator. Otherwise, the operator is prompted to start the test. In this example, the operator starts the landing gears controls sub-system test on the computer and receives the test results indicating any electrical wiring problems, faults and their locations. 
         [0056]    The operator will then visually inspect the locations at which the problems/faults have been identified. Then, the operator will carry on the repair (splice, solder, connector). 
         [0057]    Then the operator returns to the system  10  to retest the sub-system under test and the system provides a new set of test results from the electrical wiring harness. If no other problems are detected, the new harness signature is recorded in the system  10 . 
         [0058]    As a last step, the operator returns to the aircraft and connects all harness-specific connectors  29  to aircraft harness  27  equipment. Then, the operator re-runs the BITES on the sub-system under test or directly performs some trials on the aircraft harness  27  equipment. If problems are identified on the aircraft harness  27  equipment, then the operator restarts the testing procedures. 
         [0059]    If no problem occurs, a work order will be issued with the details of the repairs, validated by maintenance quality controls, and registered in the company database. Also, the new electrical harness signature, schematics updates, notes and all other aircraft changes will be recorded in the aircraft electronic logbook, which as in this example, could be a CDROM. Finally, the aircraft electronic logbook is stored in the aircraft. In the example, the logbook is on CDROM and kept in the aircraft. 
         [0060]    A test module  31  is the component that contains all testing equipment required in order to generate the measurements data to support any test specifications. The Test Specification information received from the NMS  10 , through the communication module  47 , is processed by the measurement management module  45  and sent to the appropriate testing units. 
         [0061]    As shown in  FIG. 4 , test modules  31  connect to a harness-specific connector  29  through a connector module  33 . Each connector module  33  can be customized for a specific type of harness connector  29  or can be of a generic standard connector type. A connector module  33  can be connected to more than one harness-specific connector  29 . The connector module  33  is auto-detected and controlled by the measurement management control module  45  to identify the number and type of harness-specific connectors  29  available to be connected to the test modules  31 . Then, the information about the connectors available for test is sent to the test manager module  17 . The harness-specific connectors  29  connected to the test box connector module  33  are switched and scanned by the multiplexer module  35 . 
         [0062]    The multiplexer module is a circuit switch multiplier, which can be cascaded as needed to achieve a predetermined number of test points. It is controlled by the measurement management module  45  and redirects any signals to the right harness-specific connector  29  wires to be tested. 
         [0063]    The measurement management control (MMC) module  45  receives, through the communication module  47 , test Specification from the NMS  10 . The MMC module  45  determines which testing units  37 ,  39 ,  41 ,  43  are required to produce raw data measurements. The module  45  then coordinates and synchronizes the testing units to avoid any interference. The MMC module  45  detects the test box connector module  33  connected to the test modules  31  using a hardware coded key, which is unique to each test box connector module  33 . The MMC module  45  sends the list of connectors available to connect the harness specific connector module  29  to the NMS  10 . Then, the operator will know which connector on the test box connector module  33  to plug the harness specific connector  29 . Also, the MMC module  45  controls the connector selections and the wires scanning for each connector. Finally, it produces, stores and sends test results information to the NMS  10 . The test results are produced by equipment measurements, but also by correlating the measurements received from the Standing Wave Ratio (SWR) module  39 , Time Domain Reflectometry  41  and spectrum impedance  43  modules. Such combined information is used specifically for shielding wire detection, cross-talk and coupling problems. Signal data processing is used on the return signal from the SWR module  39 , TDR module  41  and Spectrum Impedance module  43  to extract and store the information required to characterize the actual condition of the wire. Then, information from the three modules are correlated and aligned with a transmission line model and wire specification under test. Finally, the information is sent to NMS  10  to compare with the previous harness signature and to get a diagnosis. 
         [0064]    In the preferred embodiment of the present invention, the initial harness signature is generated from specifications given by the electrical harness manufacturer or tests performed on the harness. Whenever a test is performed on the wiring harness  27  and a previous signature exists, the signature comparison is performed as follows. First, a Netlist comparison is performed to verify all connectivity differences between the existing signature “connection” variable and the new measurements. The Al module  15  will perform the comparison. At the same time, the “DC measurements” and “AC measurements” variables are used to determine whether any “open or “short” problems are present within the harness. If any are detected, the Al module  15  uses the “SWR measurements” from the signature to determine the break point location of “open” or “short” within the length of the wire. As per  FIG. 5 , the system uses a test box unit “TBU” at each end of the wire, giving more precision as to the location of the break point within the length of the conductor. 
         [0065]    The Al module  15  then uses the “SWR return signals”, “TDR return signals” and “Spectrum impedance measurements” in order to detect shielding defects. The information provided by the “TDR return signals” data and the “Spectrum impedance measurements” is used with correlation algorithms well known in the art to detect a shielding defect. Whenever a shield defect has been identified, the Al module  15  determines its exact location by using the “SWR return signals” data. Signal processing including moving range, correlation and data mining algorithms are used in order to detect the location of a shielding problem. 
         [0066]      FIG. 6  illustrates the “TDR return signal” from a previous harness signature, in which no shielding defect is present.  FIG. 7  shows the “TDR return signal” received after performing a series of measurements on the same harness after some time.  FIG. 7  shows a shielding defect present in one of the wires. 
         [0067]    In the preferred embodiment of the present invention, the Al module  15  uses previously stored “TDR return signal” data to compare the received “TDR return signal” data. If a shielding problem is detected, then the Al module  15  applies correlation and data mining algorithms to the received “TDR return signals” data and the received “Spectrum impedance measurements” to determine the size of the shielding defect. The Al module  15  then uses “SWR return signals” data with moving range/Doppler algorithms to determine the location of the shielding defect. The Al module  15  can use the other variables data in the received signature whenever more data or calculations are required by the Al models to determine the size or location of shielding defect. 
         [0068]    In the case in which the analysis of the received “TDR return signal” data shows a difference when compared to the stored “TDR return signal” data, the significance of the change is assessed in order to determine the gravity of the problem. At the time of analysis of the data, the relationship between the physical wire characteristics and the electrical properties of the wire being tested would be taken into account. The relationship between the two would be used to assess the impact of a change in the physical wire characteristics on the electrical properties of the wire. Another factor taken into account by the Al module  15  when performing the assessment is the actual use of the wire being tested. For example, the type of voltage and current carried by the wire would play a role in determining the sensitivity of the electrical properties of the wire to changes in its physical characteristics. Such a complete assessment performed by the Al module  15  would allow to provide different diagnostics and recommendations depending on the gravity of the detected problem. In one case, upon detecting a shielding defect in a wire being tested, the Al module  15  might recommend that the wire be replaced, in other cases, the Al module  15  might recommend that the wire simply be submitted to a visual inspection, while in other cases, the change would simply be recorded in the electrical signature without signaling a defect. It is knowledge about the use of the wire within the harness system  27  that would allow the Al module  15  to set different pass/fail thresholds for different types of wire and to make recommendations accordingly. 
         [0069]    Now, returning to  FIG. 2 , the communication module  47  receives test specifications from the NMS  10  and sends back test results. In the preferred embodiment of the present invention, the communication module  47  is a slave transceiver (Transmitter/Receiver). The module  47  receives information from the NMS  10  and passes it to the MMC module  45 . 
         [0070]    In the preferred embodiment of the present invention, and as shown in  FIG. 2 , a test module  31  includes testing units such as: a circuit switch and polarity analyzer module  37 , a standing wave ratio (SWR) module  39 , a TDR module  41  and a spectrum impedance module  43 . 
         [0071]    The main functions of the circuit switch and polarity analyzer module  37  are to perform a continuity test and an active electronic components verification test. Also, this module  37  performs all DC testing of the transport vehicle wiring harness  27 . The module  37  contains the following two sub-modules: a circuit switch analyzer and a polarity analyzer. 
         [0072]    The circuit analyzer performs a continuity check for all possible harness connections and produces a mapping connection, which is stored in a table. The polarity analyzer performs a test to verify any active components like transistor, diode or semi-conductors in the wiring harness  27 . The polarity analyzer verifies and determines the direction of the current and gathers all the raw data required by the Al module  15 . 
         [0073]    The standing wave ratio module  39  is a testing unit, which sends a pure sinusoidal wave through each conductor of the wiring harness  27  and measures the return in terms of time, voltage and sinusoidal shape. It contains a unique “Transmission Line Model” specific to the transport vehicle industry and a state-of-art data signal processing system in order to analyze the return signal. The SWR module  39  can calculate the break point of a conductor in the wiring harness  27  using Doppler equations. This module  39  generates raw data measurements required by the NMS  10  for providing a diagnosis of the wiring harness  27 . 
         [0074]    The Time Domain Reflectometry (TDR) module  41  is a testing unit, which sends a small amplitude pulse through each conductor of the wiring harness  27  in order to characterize it. It uses Fast Fourier Transforms (FFT) and Laplace Transforms to compute and produce raw data measurements and a state-of-art data signal processing system to extract and analyze the return signal. 
         [0075]    The spectrum impedance module  43  is a testing unit, which measures AC resistance with different signal voltage over a spectrum of specific frequencies. The spectrum impedance module  43  produces polar and vector representations for each wire impedance over a specific frequency spectrum (Nyquist plot). Also, the spectrum impedance module  43  uses a state-of-art of data signal processing system to extract and analyze the return signal for each frequency. The module  43  generates raw data required by the NMS  10  and stores the information in a table. In the preferred embodiment of the present invention, this module  43  has auto-range calibration abilities using the successive approximation method. 
         [0076]    The embodiments of the invention described above are intended to be exemplary only. The scope of the invention is therefore intended to be limited solely by the scope of the appended claims.