Recommendation of Sensors for Vehicle Transmission 

Diagnostics

by Kwok F. Tom

ARL-TN-0485 May 2012

Approved for public release; distribution unlimited.
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Army Research Laboratory 

Adelphi, MD 20783-1197 

ARL-TN-0485 May 2012 

Recommendation of Sensors for Vehicle Transmission 

Diagnostics 

Kwok F. Tom 

Sensors and Electron Devices Directorate, ARL 

Approved for public release; distribution unlimited. 
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1. REPORT DATE (DD-MM-YYYY)

May 2012

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October 2010 to September 2011

4. TITLE AND SUBTITLE

Recommendation of Sensors for Vehicle Transmission Diagnostics

5a. CONTRACT NUMBER

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6. AUTHOR(S)

Kwok F. Tom

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7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

U.S. Army Research Laboratory

ATTN: RDRL-SER-E

2800 Powder Mill Road

Adelphi MD 20783-1197

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 REPORT NUMBER

ARL-TN-0485

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

TARDEC

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Warren MI 48397-5000

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13. SUPPLEMENTARY NOTES

14. ABSTRACT

The U.S. Army Research Laboratory (ARL) had entered into a Technical Program Agreement (TPA) with the U.S. Army Tank 

and Automotive Research and Development Center (TARDEC) for research on Prognostics for Ground Vehicles. One of the 

tasks under this agreement was to survey/investigate sensors for diagnostics related to ground vehicles as related to 

transmissions.

15. SUBJECT TERMS

Sensors, diagnostics, transmission, FMECA, FMEA

16. SECURITY CLASSIFICATION OF: 

17. LIMITATION

OF ABSTRACT

UU

18. NUMBER

OF PAGES

22

19a. NAME OF RESPONSIBLE PERSON

Kwok F. Tom

a. REPORT

UNCLASSIFIED

b. ABSTRACT

UNCLASSIFIED

c. THIS PAGE

UNCLASSIFIED

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(301) 394-2612

Standard Form 298 (Rev. 8/98) 

Prescribed by ANSI Std. Z39.18 
iii

Contents 

List of Figures iv

List of Tables iv

1. Introduction 1

2. Data Sources 1

3. Transmission as Line Replaceable Unit (LRU) 2

4. Current Capabilities 2

5. Common Essential Parameters 5

6. Summary of Proposed Sensors 7

7. References 9

Appendix 11

List of Symbols, Abbreviations, and Acronyms 14

Distribution List 15
iv

List of Figures 

Figure 1. Tachometer and diagnostics gauge ..................................................................................4

Figure 2. Fuel and diagnostics gauge ..............................................................................................5

List of Tables 

Table 1. Fluid oxidation measurement limits. .................................................................................6

Table 2. Operating oil temperature range. ......................................................................................6

Table 3. Transmission oil temperature versus distance of service. ..................................................7
1

1. Introduction 

The U. S. Army Tank and Automotive Research and Development Center (TARDEC) is 

performing research and development on programs related to ground vehicles. One of the 

primary components associated with the mobility of ground vehicles is the transmission. Its 

basic operation converts the engine’s energy into a form that can be used to operate the drive 

train. The transmission is a series of mechanical components such as gears, bearings, and 

clutches that operate in a synchronous motion in order to change the engine speed rotation into 

torque. Due to the contact between the components and the heat generated in this process, 

transmission fluid is used as a lubricant and coolant for the rotating components within the 

transmission housing. 

To assist in TARDECs efforts, the U.S. Army Research Laboratory (ARL) entered into a 

Technical Program Agreement (TPA) with TARDEC on TPA, #TA-SE-2010-05. As part of the 

TPA, ARL agreed to perform the following task: Perform survey/investigation of sensors and

algorithm application to providing diagnostic capabilities as related to ground vehicle, e.g.,

Allison 2500 transmission. 

The Allison 2500 transmission is used on the Mine Resistant Ambush Protected (MRAP) 

vehicle, RG-31A2. This vehicle has a five-speed Allison SP series automatic transmission. The 

transmission is electronically controlled by the Transmission Control Module (TCM) to operate 

the transmission gear selector. Cooling of the transmission fluid is provided by remote-mounted 

oil cooler in front of the vehicle (1). In addition to this particular transmission, other 

transmissions were reviewed to formulate a sensor list for transmission in general. 

2. Data Sources 

A survey of various documents was conducted in order to formulate sensors candidates for 

diagnostic capabilities as related to transmissions. These documents dealt with the Allison 

transmission as well as other manufacturers. Some documents provided a great detail 

investigation of the transmission as conducted as part of a Degrader Studies by Applied Research 

Laboratory, Pennsylvania State University (ARL–Penn State) and the Failure Mode Effect, 

Cause, and Criticality (FMECA) Study on the Bradley Transmission by Global Technology 

Connection, Inc. A FMECA is a reliability analysis tool used to identify the failure mode and its 

effect on performance, and to rank the impact of such failures. These studies identified the 

sensors that would be appropriate to help detect and diagnose associated failure mechanisms. In 

a Degrader Study, analysis is performed by using a FMECA study along with other 

information—parts replacement data, customer interviews, and Original Equipment 
2

Manufacturer (OEM) survey. Part replacement data is derived from the Operating and Support 

Management Information System (OSMIS) and Logistics Support Agency (LOGSA) databases 

(2).

The Degrader Studies were performed on the M2/M3 Bradley Fighting Vehicle and the M1 

Abrams Tank. The transmission in the M2/M3 Bradley Fight Vehicle is the HMPT-500-3EDB 

by L3. An Allison X-1100-3B transmission is used in the Abrams Tank. The FMECA was 

performed on both the Bradley and Abrams transmissions. A Failure Mode and Effects Analysis 

(FMEA) had been performed on the Allison 2500 SP transmission by ARL–Penn State. Other 

documents used were Army Technical User and Maintenance Manuals, in addition to other 

documentation from Allison. 

3. Transmission as Line Replaceable Unit (LRU) 

One of the components that was identified as a top replacement item is the transmission based on 

the Degrader Studies. For the Bradley Fighting Vehicle, 16% of the Field Service 

Representatives (FSR) report indicated that the transmission is a high replacement item. The 

transmission is treated as a LRU that is replaced without minimal troubleshooting process. 

Better fault isolation would be of great benefit (3). Results from the Abrams Degrader Study 

indicated that 55% of the FSR reports were related to the transmission. This is significantly 

high, but the report indicates that failure rates have improved recently. The paradigm on the 

Abrams Tank is to treat the transmission as a LRU that is sent back to the depot for repairs. Part 

of the difficulty is because the embedded diagnostic is fairly limited and maintainers are not 

well-trained in servicing the transmission (4).

4. Current Capabilities 

There are different diagnostic capabilities around the spectrum of transmissions. Even on the 

same vehicular type, the configuration varies in terms of embedded diagnostic capabilities. In 

the case of the Bradley Fighting Vehicle, there are two configurations—standard and enhanced 

models. With the Chassis Modernization and Embedded Diagnostics configuration, an 

embedded diagnostic capability is provided through the addition of sensors on several systems. 

Diagnostic capability is available on the generator, batteries, starter, fuel pumps, fuel filter, 

engine, and transmission oil pressure and temperature. Part of the problem associated with the 

transmission is the capability of diagnosing the failure classification to be mechanical or 

electronic in nature. FSR reports that there is a lack of proper diagnostic tools. One unit 

indicated that a Tech2Scan diagnostic tool device was extremely helpful, but not supplied as part 

of their arsenal of tools (3).
3

There are many sources of diagnostic capabilities offered by the OEM and independent 

diagnostic developers. One such company is the Nexiq Technologies Company, which produces 

the Pro-LinkiQ scan tool. Their scan tool is flexible enough to accommodate various 

manufacturers such as Detroit Diesel, Caterpillar, International, Mack, and Volvo. The scan tool 

is application-specific where software unique to a particular manufacturer is installed to a 

common tool. This application permits the reading of proprietary fault codes, clearing of 

proprietary fault codes, viewing and reset of trip information, viewing of data lists (for example, 

sensors, switch status, proprietary data lists), and performance of special tests (for example, 

cylinder test, injector test) (5). This is just an example of secondary diagnostic capability being 

offered through after-market service tools. 

The OEMs have spent a great deal of time in the development of their transmission and have 

provided some level of diagnostic capability. These transmissions are fully automatic torqueconverters with electronic controls. In the case of the Allison 2000 series transmission, there are 

five major components connected through a wiring harness: 

• TCM 

• Engine throttle position sensor or direct electronics communication of throttle information 

• Engine, turbine, and output speed sensors 

• NSBU switch 

• Control value module 

This transmission has adaptive shifting through the monitoring of critical parameters for clutch 

engagement. Solenoids and a pressure switch module form the Control value module. A 

thermistor is contained within the pressure switch module in order to monitor the sump fluid 

temperature. Sensor information is provided to the TCM through various sensors such as throttle 

position, speed sensor, pressure switch module, and NSBU switch. Activation of specific 

solenoids on the Control value module is executed through the processing of the sensor 

information. This provides for closed-loop adaptive shifting that optimizes the clutch 

engagement and makes ongoing adjustments to improve subsequent shifts (6).

The manufacturers have provided some level of diagnostic capabilities that can be accessed 

through the Controller Area Bus (CAN) interface. This communication interface provides a 

digital exchange of information between the Allison transmission and TCM. Diagnostic 

information can be collected and provided through Allison or secondary service tools. Allison 

Diagnostic Optimized Connection (DOC) is a software tool that was developed to provide 

diagnostic monitoring of its transmission. This communicates with the TCM to read the status of 

transmission clutches and summary of Diagnostic Trouble Codes (7, 11).

Similar capabilities are offered by other OEMs. On the Bradley Fighting Vehicle, the 

transmission is the Hydromechanical Power Transmission (HMPT). Combat Propulsion Systems 
4

(L-3 CPS) developed and designed this transmission. The electronics is comprised of two 

assemblies: Transmission Electronic Controller (TEC) and Transmission External Memory 

Module (TEMM). The function of TEC is to acquire the various transmission sensors outputs 

and desired operation in order to properly execute the necessary activation of the stepper motors 

and solenoids. Contained in the TEC are all control algorithms, and fault detection logic and 

communication interfaces. The other electronic assembly, TEMM, is a memory storage device 

that retains the transmission history, usage, and faults. Critical fault parameters are stored with 

information around the event. This information can be accessed through a scan tool and is 

beneficial for troubleshooting (12). 

Typically, the sensor information is processed by the OEM and fault codes generated and stored 

on the vehicle computer. Scan tools that are accessing this information can provide the 

capability for troubleshooting. In general, the OEM provides some simplified diagnostic 

summary through dashboard indicators. Figures 1 and 2 are images for the Heavy Expanded 

Mobility Tactical Truck (HEMTT) that uses the Allison 4500 SP/5 automatic transmission (8).

Figure 1. Tachometer and diagnostics gauge

Icons (indicators)

a. Low oil pressure

b. High coolant temperature

c. Check engine indicating engine has logged a fault code event
5

Figure 2. Fuel and diagnostics gauge

5. Common Essential Parameters

A significant amount of testing has been conducted by the various transmission manufacturers in 

order to evaluate the performance and reliability of their products. One of the outcomes of these 

types of testing has been the OEM specification of fluids and interval for servicing. This 

information has been reduced to recommendations that hopefully represent the typical usage. In 

this situation, it is very difficult to estimate what represents the typical use in military vehicles. 

The function of the transmission fluid is to cool, lubricate, and transfer hydraulic power to drive 

the vehicle. A simple, but very important parameter is the proper fluid level. When the fluid 

level is low, there is a lack of adequate fluid to function optimally. This will impact the life and 

reliability of the converter, bushings, bearings, and clutches. A high fluid level will result in 

aeration. In this state, the transmission will shift erratically or overheat. Temperature and fluid 

level are simple parameters that can be measured.

Transmission components are sensitive to contamination of its fluid. Solid particulates are an 

indication of a serious problem. The durability of the transmission internal components, such as 

bushing, bearings, and gears, can be seriously affected. Fine particulates have a potential to 

Icons (indicators)

a. Check Transmission (get fault messages from TCU)

b. Low fuel warning

c. High transmission temperature

d. Low air warning from front or rear system
6

affect the functionality of the control value module. This could degrade the operation of the 

solenoid to the point that there is a failure or the clutch plates could stick. 

The viscosity of the fluid is critical to the lubricity of the transmission components. 

Contamination of the fluid with water and/or ethylene glycol coolant mixtures affects the 

reliability and durability of the components. A mixture of this type will have a deterioration 

effect on both the non-metallic components, such as gasket material, and on the metallic bearings 

and gears. Allison recommends that transmission protection and fluid changes can be optimized 

by monitoring the oxidation according to the test and limit shown in table 1 (6, 9). 

Table 1. Fluid oxidation measurement limits. 

Test Limit

Viscosity 25% change from new fluid

Total Acid Number +3.0* change from new fluid (mg of KOH required to 

neutralize a gram of fluid)

The transmission fluid temperature is one of the most important indicators of transmission 

health. Temperature effects on transmission operation are summarized in table 2. This table lists 

the effect for standard transmission oil (Synthetic Universal Automatic Transmission Fluid), but 

the information is applicable for most transmission oil. 

Table 2. Operating oil temperature range. 

Temperature (Fahrenheit) Effect

150° F The minimum operating temperature.

175–200° F Normal pan oil temperature operating range.

275° F Maximum allowable oil pan temperature for short 

durations during long hill climbs.

300° F Damage occurs to internal transmission parts, including 

warping of metal parts, degradation of clutches, and 

melting of seals. Transmission oil oxidizes, (forming 

varnish like substances causing further clutch slippage 

and compounding heat buildup) and transmission oil life 

is extremely short.

The automatic transmission fluid should be able to provide 100,000 miles of service before 

replacement at an operating temperate of 175 °F. Oil oxidation rate doubles with each 20 °F 

increase in oil temperature. Table 3 illustrates the temperature effect on the standard 

transmission oil life as a function of temperature (10).
7

Table 3. Transmission oil temperature versus distance of service. 

Temperature (Fahrenheit) Distance (Miles)

175O100,000

195O50,000

215O25,000

235O12,500

255O6,250

275O3,125

295O1,500

315O750

6. Summary of Proposed Sensors 

Reports and analysis were reviewed for various transmissions on different ground vehicles. 

Information for Allison X-1100-3B, Allison 2500 SP, and L-3 Combat Propulsion Systems’ 

HMPT transmission were part of this review. Identification of sensors that may be used can be 

easily derived from FMECA and FMEA analysis. Although these transmissions are different in 

design and hardware, the basic functions are similar. From these evaluations, it is clear that there 

are some embedded sensors and processing presently on transmission from the OEMs. The 

diagnostic capability exists at a fundamental level. Another piece of information to come out of 

these reports was the importance of “human perception.” The human being is also a sensor with 

processing capabilities, but is not necessarily accurate in terms of correctly diagnosing the 

problem (3, 4). 

Part of the hurdle in using the capability is the lack of access to the scanning tools to read the 

diagnostic fault codes. In addition, since the transmission is complex machinery, the knowledge 

and necessary facility does not exist to perform repair function out in the field. The transmission 

is treated LRU, but proper diagnostic ability would reduce the necessary actions that result from 

incorrect or improper classification of fault. Some of the sensing information is binary as a 

result of the switches on the oil pressure, temperature, and oil filter in the case of the Abrams 

Tank (4). This is very limited in terms of diagnostic resolution, with enhanced diagnostic 

capability derived with replacement with higher fidelity sensors. 

The sensing capabilities between various transmissions are not necessarily identical, but similar 

sensors would be needed to provide common sensing capabilities. The lists of sensors are as 

follows: 

• Viscosity 

• Fluid level 

• Fluid pressure 
8

• Temperature 

• Contaminant 

• Voltage & Current 

• Vibration (Advanced with signal processing techniques) 

The addition of these sensors is only part of the solution for diagnostic capabilities. Proper 

interpretation of these signals will have to be developed. Algorithms, framework, and 

methodology are necessary and very important elements that will be required, in addition to 

incorporating sensors. Sensors provide the data, and information is developed from the 

processing of the data. Correct interpretation of the information provides the knowledge for 

correct and enhanced diagnostic capability. 
9

7. References 

1. Allison 2500 SP Transmission FMEA (Failure Mode and Effects Analysis). 

2. Platform Degrader Analysis For The Design And Development Of Vehicle Health 

Management Systems (VHMS), Jeffrey C. Banks, Karl M. Reichard, Jason A. Hines and 

Mark S. Brought, The Journal of the Reliability Information Analysis Center, 2Q 2010. 

3. HBCT Vehicle Degrader Analysis and Potential Health Management Solutions Analysis for 

the M2/M3 Bradley Fighting Vehicle, Final Report, August 2008, Applied Research 

Laboratory, The Pennsylvania State University. 

4. HBCT Vehicle Degrader Analysis and Potential Health Management Solutions Analysis for 

the M1A2 SEP v2 Abrams Tank and M1A1 SA Abrams Tank, Final Report, August 2008, 

Applied Research Laboratory, The Pennsylvania State University. 

5. Heavy-Duty Diagnostics, Product Catalog, NEXIQ TECHNOLOGIES, 2010.

6. Operator’s Manual, 1000 and 2000 Product Families, Allison Transmission, OM3063EN, 

2007.

7. Allison 4th Generation Controls – Jan 2010 and Jun 2010 software releases, Allison 

Transmission, June 2010. 

8. Program of Instruction, Instructor and Student, Operator/Operator Maintenance, HEMTTA4 

(All Variants) Heavy Expanded Mobility Tactical Truck. 

9. http://www.maitlanddiesel.com.au/allison_transmission.php. 

10. Prognostics Enhanced Diagnostic Systems for Bradley (P{EDS-Bradley) Drive Train 

Components, Global Technology Connection, Inc., November 2009. 

11. http://www.allisontransmission.com/servlet/DownloadOnDemand?

ApplicationID=155&DownloadID=32&... 

12. HMPT Operation 101, L3 Combat Propulsion Systems, July 2010. 
10

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11

Appendix 

Analysis of FMEA on Allison 2500 SP Transmission. Extracted from ARL-VTD Mechanics 

Division TPA Year-End Report, TPA TA-VT-2010-02, Condition-Based Maintenance Plus for 

Ground Vehicles.

Failure Mode Potential Causes Sensing Strategies Sensor Availability

Contaminated 

transmission 

lubrication

Internal transmission 

failure; Clogged filter; 

Excessive heat

Transmission fluid 

contaminant sensing; Fluid 

temperature sensing

Fluid contaminant sensor; 

Fluid temperature sensor

Engine excessively 

revs on full throttle up 

shifts

Internal transmission 

failure; Incorrect 

calibration; Incorrect fluid 

level; Erratic speed sensor 

signal

Current/Voltage sensing at 

sensor terminals; Fluid level 

sensing

Current/Voltage sensor 

measured at sensor 

terminals; Fluid level sensor

Excessive slippage and 

Clutch chatter

Internal transmission 

failure; Faulty torque 

converter; Clutch pressure 

low; Fluid level low; 

Aerated fluid; 

Transmission control 

module incorrectly 

calibrated; Throttle 

position sensor failed; 

Incorrect fluid level; Worn 

clutch pack; Incorrect 

speed sensor

Fluid pressure sensing; 

Contaminant sensing; 

Electrical disconnect sensing 

at sensors; Fluid level 

sensing

Fluid pressure sensor; 

Contaminant sensor; 

Current/Voltage sensor at 

terminals/wiring; Fluid level 

sensor

Excessive stationary 

vehicle creep in first 

and reverse gear

Internal transmission 

failure; Engine idle speed 

set too high

Fluid pressure and 

temperature sensing; 

Contaminant sensing; 

Analyze Engine PHM

Fluid pressure sensor; 

Temperature sensor; 

Contaminant sensor; 

Investigate Engine PHM 

sensing

Fluid leak at output 

shaft

Seal at output flange 

damaged; Worn output 

shaft bearing; Flange worn 

at seal surface

Fluid temperature/Pressure 

sensing; Contaminant 

sensing

Fluid temperature/Pressure 

sensor; Contaminant sensor

Fluid leaking from 

fluid filler tube and/or 

breather

Fluid contaminated with 

foreign liquid; Blocked 

breather; Incorrect fluid 

level; Dipstick loose or 

seal worn

Fluid contaminant sensing; 

Fluid level sensing

Fluid contaminant sensor; 

Fluid level sensor

Fluid leaks Transmission input seals 

worn/damaged; Damaged 

gaskets; Blocked breather; 

Cracked casing; Loose 

fluid filler or drain plug; 

Worn output shaft bearing; 

Fluid level too high

Fluid level sensing; Fluid 

temperature/pressure 

sensing

Fluid level sensor; Fluid 

temperature/pressure sensor
12

Intermittent noise –

buzzing (acoustic 

wave)

Low main pressure causes 

main regulator to oscillate; 

Internal transmission 

failure; Air leak in oil 

suction screen canister; 

Clogged filter; 

Transmission fluid level 

low; Incorrect sump filter 

installed; Faulty torque 

converter; Aerated fluid

Fluid level sensing; Fluid 

pressure sensing; 

Contaminant sensing

Fluid level sensor; Fluid 

pressure sensor; 

Contaminant sensor

Low lubrication 

pressure

Excessive internal fluid 

leakage; Converter relief 

value sticking; Lubrication 

regulator value sticking; 

Incorrect fluid level; 

Blocked suction filter; 

Cooler lines restricted or 

leaking; Faulty pump

Fluid level sensing; Oil 

pressure sensing across 

pump; Pressure sensing in 

cooler lines

Fluid level sensor; Pressure 

sensor

Low main pressure in 

all ranges

Internal transmission 

failure; Incorrect fluid 

level; Faulty pump; 

Blocked suction filter

Fluid level sensing; Pressure 

sensing across pump & 

suction filter

Fluid level sensor; Pressure 

sensor

Low main pressure in 

specific ranges, normal 

pressure in other 

ranges

Internal transmission 

failure; Faulty pump

Fluid pressure sensing 

across pump

Fluid pressure sensor

Low stall speeds Engine not performing 

efficiently due to blocked 

injectors, dirty air filter, 

throttle linkage problem, 

etc.

Examine sensing for Engine 

PHM

Integrate appropriate Engine 

PHM sensors

No transmission 

control module light at 

ignition

Incorrect wiring to and 

from transmission control 

module; Faulty light bulb; 

Transmission control 

module connected to 

battery power instead of 

ignition power

Current/Voltage sensing for 

control module wire harness

Current/Voltage sensor

Overheating in all 

ranges

Cooler flow loss due to 

internal transmission 

leakage; Engine 

overheating; Fluid cooler 

lines restricted; Air flow to 

cooler obstructed; 

Incorrect fluid level; 

Aerated fluid

Fluid temperature sensing; 

Fluid pressure sensing; Air 

flow to cooler pressure 

sensing; Fluid level sensing; 

Contaminant sensing

Fluid temperature/Pressure 

sensor; Air flow pressure 

sensor; Fluid level sensor; 

Contaminant sensor

Shudder when shifting 

into forward or reverse

Internal transmission 

failure

Fluid level sensing; Fluid 

temperature/pressure 

sensing; Contaminant 

sensing

Fluid level sensor; Fluid 

temperature/pressure sensor; 

Contaminant sensor

Transmission control 

module light flashes 

intermittently

Loose wire to transmission 

control module light; 

Faulty vehicle wiring; 

Faulty ground connection

Current/Voltage sensing on 

wiring harness

Current/Voltage sensor for 

wire harness (wire chafing)
13

Transmission control 

module light will not 

extinguish after engine 

has started

Faulty transmission control 

module light relay; Faulty 

transmission control 

module; Fault harness

Current/Voltage sensing on 

wiring harness

Current/Voltage sensor for 

wire harness (wire chafing)

Transmission does not 

shift properly (rough 

shifts, shifts occurring 

at too low or too high 

speeds)

Sticking valves in control 

valve body; Leaking trim 

solenoids; Low main 

pressure; Faulty 

speed/sensor/circuit; Loose 

or damaged speed gear; 

Faulty throttle 

sensor/circuit; Incorrectly 

calibrated electronic 

speedometer; Incorrect 

fluid level; Contaminated 

fluid; Engine idle speed 

too fast

Fluid level sensing; Fluid 

temperature/pressure 

sensing; Current/Voltage 

sensing for possible 

electrical disconnects at 

sensors and on wire harness

Fluid level sensor; Fluid 

temperature/Pressure sensor; 

Current/Voltage sensor at 

sensor terminal& on wiring 

harness (wire chafing)

Transmission will not 

make a specific shift

Extreme fluid temperature; 

Low engine power; 

Incorrect shift calibration; 

Faulty speed sensor/circuit; 

Faulty temperature 

sensor/circuit

Fluid temperature sensing; 

Current/Voltage sensing for 

sensors & wiring harness

Fluid temperature sensor; 

Current/Voltage sensor 

(wire chafing)

Transmission will not 

select

Low hydraulic pressure; 

Throttle position sensor or 

linkage not functioning 

properly; Faulty speed 

sensor; Faulty wiring in 

Transmission control 

module

Fluid pressure sensing; Fluid 

level sensing; 

Current/Voltage sensing for 

sensors and wiring harness

Fluid pressure sensor; Fluid 

level sensor; 

Current/Voltage sensor 

(wire chafing)

Transmission will not 

stay in forward or 

reverse

Faulty solenoid; Low 

hydraulic pressure; Control 

main filter clogged; 

Transmission fluid level 

low

Fluid pressure sensing; Fluid 

level sensing; 

Current/Voltage sensing at 

solenoid

Fluid pressure sensor; Fluid 

level sensor; 

Current/Voltage sensor
14

List of Symbols, Abbreviations, and Acronyms 

ARL U.S. Army Research Laboratory 

ARL–Penn Applied Research Laboratory, Pennsylvania State University 

CAN Controller Area Bus 

DOC Diagnostic Optimized Connection 

FMEA Failure Mode and Effects Analysis 

FMECA Failure Mode Effect, Cause, and Criticality 

FSR Field Service Representatives 

HEMMTT Heavy Expanded Mobility Tactical Truck 

HMPT Hydromechanical Power Transmission 

LOGSA Logistics Support Agency 

LRU Line Replaceable Unit 

MRAP Mine Resistant Ambush Protected 

OEM Original Equipment Manufacturer 

OSMIS Operating and Support Management Information System 

TARDEC U.S. Army Tank and Automotive Research and Development Center 

TCM Transmission Control Module

TEC Transmission Electronic Controller 

TEMM Transmission External Memory Module 

TPA Technical Program Agreement 
15

NO. OF 

COPIES ORGANIZATION 

1 ADMNSTR 

ELEC DEFNS TECHL INFO CTR 

 ATTN DTIC OCP 

 8725 JOHN J KINGMAN RD STE 0944 

 FT BELVOIR VA 22060-6218 

1 US ARMY RSRCH DEV AND ENGRG CMND 

 ARMAMENT RSRCH DEV & ENGRG CTR 

 ARMAMENT ENGRG & TECHNLGY CTR 

 ATTN AMSRD AAR AEF T J MATTS 

 BLDG 305 

 ABERDEEN PROVING GROUND MD 21005-5001 

1 US ARMY INFO SYS ENGRG CMND

 ATTN AMSEL IE TD A RIVERA 

 FT HUACHUCA AZ 85613-5300

2 US ARMY TARDEC 

 ATTN RDTA RS C BECK

 ATTN RDTA RS K FISCHER 

 WARREN MI 48397-5000 

1 US GOVERNMENT PRINT OFF 

 DEPOSITORY RECEIVING SECTION 

 ATTN MAIL STOP IDAD J TATE 

 732 NORTH CAPITOL ST NW

 WASHINGTON DC 20402 

1 US ARMY RSRCH LAB 

 ATTN RDRL VTM M MURUGAN 

 BLDG 4603 

 ABERDEEN PROVING GROUND MD 21005 

5 HCS US ARMY RSRCH LAB 

1 PDF ATTN IMNE ALC HRR MAIL & RECORDS MGMT 

 ATTN RDRL CIO LL TECHL LIB 

 ATTN RDRL CIO LT TECHL PUB 

 ATTN RDRL SER E K TOM (2 HCS, 1 PDF) 

 ADELPHI MD 20783-1197 
16

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