Patent Description:
Existing transport refrigeration systems are used to cool containers, trailers, railcars or other similar transport units (typically referred to as a "refrigerated transport unit"). Modern refrigerated transport units are commonly used to transport perishable items such as produce and meat products. In such a case, the transport refrigeration systems are used to condition the air inside a cargo space of the transport unit, thereby maintaining a desired temperature and humidity during transportation or storage. Typically a transport refrigeration unit (TRU) is attached to the transport unit to facilitate a heat exchange between the air inside the cargo space and the air outside of the transport unit.

<CIT> discloses an engine control system which operates off a microprocessor of an engine control module, ECM, and which will automatically start a combustion engine upon any one of a series of enabler signals indicative of low battery voltage, low cab temperature and/or low engine temperature. The system also includes safety measures which will override the automatic starting of the engine. For instance, the vehicle will not automatically start if a vehicle speed is detected, if the parking brake is not set, if the ignition key is not in the "on" position, or if the hood is open. Moreover, the system is configured not to start if the fuel level is low, thus preventing an unintended depletion of fuel which could strand the vehicle and operator.

<CIT> discloses a mobile environment-controlled unit having a structure, a compartment supported by the structure, and an environmental-control system in environmental communication with the compartment. The environmental-control system is configured to control an environmental parameter of the compartment. The environmental-control system includes an internal combustion engine, having a starter, powering the environmental-control system; a battery powering the starter; and a controller. The controller monitors battery health status, predicts battery failure, and communicates the predicted battery failure. Also, described is a method of operating the mobile environment-controlled unit and a controller for controlling the mobile environment-controlled unit.

<CIT> discloses a method of controlling energisation of a coil of a motor vehicle starter contactor the coil is energised in a pick-up mode to close the contactor and then in a latching mode to hold the contactor closed. A voltage corresponding to the supply voltage of the electric motor of the starter is measured, a drop in this voltage corresponding to the closing of the contactor is detected, and the coil of the contactor is energised in latching mode after a predetermined time-delay from detection of the voltage drop.

The present invention is defined by the appended independent claims, to which reference should now be made. Further optional features of the invention are defined by the dependent claims.

The embodiments described herein relate to systems and methods for starting an electronically controlled engine of a TRS by supplying power from a battery to the electronically controlled engine.

The electronically controlled engine includes an engine control unit (ECU). The embodiments described herein can start the electronically controlled engine with a low supply voltage, and can achieve a complete engine start even when the ECU receives a reset instruction during the startup of the electronically controlled engine.

The embodiments provided herein can improve engine starting performance with a low voltage supply. When a battery for supplying power to an engine works in an extremely cold weather, and/or the battery has a poor battery condition, it is common for the battery to provide an amount of power with a low voltage for the engine. With the low voltage supply, the battery may stop providing power to an engine starter when the engine is set to a pre-crank state and the engine may not be completely started. The embodiments provided herein allow the battery to supply power to the engine starter continuously until the electronically controlled engine is completely started.

A method of starting an electronically controlled engine of a transport refrigeration system (TRS), is provided. The electronically controlled engine is configured to supply power to a transport refrigeration unit (TRU) of the TRS. The electronically controlled engine includes an engine control unit (ECU). The TRU includes a TRS controller. The electronically controlled engine further includes a starter for initiating the engine's operation. The method includes waiting for an instruction to begin an engine startup; activating a keyswitch signal, via the TRS controller, for closing a first switch of the ECU (an "enable switch") to supply current from a battery to the ECU; and activating a run signal via the TRS controller to set the ECU and the electronically controlled engine to a pre-crank state. The method further includes transmitting a CAN (Controller Area Network) message, via the TRS controller, for closing a second switch of the ECU to supply power from the battery to the starter to start cranking of the engine; upon initiating startup of the engine, determining whether a voltage supplied to the starter is below a voltage threshold for a time period; and when the voltage supplied to the starter is below the voltage threshold for the time period, the TRS controller continuously transmitting the CAN message at a predetermined rate to the ECU to keep the keyswitch signal and the run signal active until the engine startup is complete.

A system for starting an electronically controlled engine of a transport refrigeration system (TRS), is provided. The TRS includes a transport refrigeration unit (TRU) and the electronically controlled engine is configured to supply power to the TRU. The TRS includes a TRS controller, an engine control unit (ECU), and a TRS controller to ECU interface. The TRS controller to ECU interface is configured to transmit a CAN message between the TRS controller and the ECU. The TRS controller to ECU interface includes a keyswitch signal connection configured to send a keyswitch signal, a CAN communication connection configured to send a CAN message, and a run signal connection configured to send a run signal. A starter control is connected to the ECU and is configured to control power supply from a battery to a starter to start the engine. The TRS controller is also configured to determine whether a voltage supplied to the starter is below a voltage threshold for a time period when startup of the engine is initiated. The TRS controller is further configured to continuously transmit the CAN message at a predetermined rate to the ECU to keep the keyswitch signal and the run signal active until engine startup is complete when the voltage supplied to the starter is below the voltage threshold for the time period.

In some embodiments, the starter control includes a starter relay that includes a relay activator and a couple of contacts. The ECU includes a first switch (an "enable switch") configured to control an ECU main relay, and a second switch to control the starter relay. The relay activator of the starter relay is supplied power by the battery, a starter relay output of the TRS controller, or the keyswitch signal connection. One of the contacts of the starter relay is connected to a starter coil of the starter, and the other of the contacts is connected to the battery.

Referring now to the drawings in which like reference numbers represent corresponding parts throughout.

References are made to the accompanying drawings that form a part hereof, and in which is shown by way of illustration of the embodiments in which the methods and systems described herein may be practiced. The term "refrigerated transport unit" generally refers to, for example, a conditioned trailer, container, railcars or other type of transport unit, etc. The term "transport refrigeration system" or "TRS" refers to a refrigeration system for controlling the refrigeration of an in conditioned space of the refrigerated transport unit. The term "conditioned air" refers to air that has been treated so as to maintain a desired condition, for example, desired temperature or desired moisture control. The term "conditioned space" or "conditioned environment" refers to a space, a zone or an environment that receives the treated air.

It will be appreciated that the embodiments described herein may be used in any suitable transport unit such as a ship board container, an air cargo cabin, an over the road truck cabin, etc..

<FIG> illustrates a side view of a refrigerated transport unit <NUM> that includes a transport unit <NUM> and a transport refrigeration system (TRS) <NUM>. The TRS <NUM> includes a transport refrigeration unit (TRU) <NUM> connected to a generator set (genset) <NUM>. The transport unit <NUM> includes a roof <NUM>, a floor <NUM>, a front wall <NUM>, a rear wall <NUM>, and opposing sidewalls <NUM>, <NUM>. The TRU <NUM> is positioned on the front wall <NUM> of the transport unit <NUM>. A conditioned cargo space <NUM> is defined by the roof <NUM>, the floor <NUM>, the front wall <NUM>, the rear wall <NUM>, and the opposing sidewalls <NUM>, <NUM>. The TRS <NUM> is configured to transfer heat between the conditioned cargo space <NUM> and the outside environment.

As shown in <FIG>, the TRU <NUM> is enclosed in a housing <NUM>. The TRU <NUM> is in communication with the conditioned cargo space <NUM> and controls the temperature in the conditioned cargo space <NUM>. The TRU <NUM> includes a closed refrigerant circuit (not shown) powered by the genset <NUM>, which regulates various operating conditions (e.g., temperature, humidity, etc.) of the conditioned cargo space <NUM> based on instructions received from a TRS controller (not shown). The TRU <NUM> includes a TRS controller (not shown) that regulates various operating conditions (e.g., temperature, humidity, etc.) of the conditioned cargo space <NUM> and is powered by the generator set <NUM>. The TRU <NUM> also includes a closed refrigerant circuit (not shown). The closed refrigerant circuit regulates various operating conditions (e.g., temperature, humidity, etc.) of the conditioned cargo space <NUM>, and includes an Electronic Throttle Valve (ETV, not shown), a compressor (not shown) coupled to a condenser (not shown) and an evaporator (not shown) that cools the conditioned cargo space <NUM> and any perishable cargo contained therein.

The generator set <NUM> generally includes an electronically controlled engine (not shown), an electronic controller unit (ECU) (not shown), a fuel container (not shown) and a generator (not shown). The electronically controlled engine may be an internal combustion engine (e.g., diesel engine, etc.) that may generally have a cooling system (e.g., water or liquid coolant system), an oil lubrication system, and an electrical system (none shown). An air filtration system (not shown) filters air directed into a combustion chamber (not shown) of the engine. In some embodiments the engine is not specifically configured for the TRS <NUM>, but can be a non-industrial engine such as, for example, an automotive engine. The fuel container is in fluid communication with the engine to deliver a supply of fuel to the engine.

The electronically controlled engine is further controlled by the ECU. The ECU can be configured to regulate an amount of fuel delivered to the electronically controlled engine and can be configured to operate the electronically controlled engine at multiple speeds. The ECU is generally configured to allow the electronically controlled engine to be maintained at a chosen speed regardless of the load seen by the engine. As discussed in more detail below, the ECU is connected to and communicates with the TRS controller.

While the transport unit <NUM> in <FIG> is directed to a trailer type transport unit, it will be appreciated that the embodiments directed to systems and methods in the TRS <NUM> for a low voltage engine start can also be used, for example, in a truck type transport unit, a container type transport unit, etc..

<FIG> illustrates a schematic of a portion of a TRS <NUM> for starting an electronically controlled engine with a low supply voltage, according to a first embodiment. The TRS <NUM> includes a TRS controller <NUM>, an engine control unit (ECU) <NUM>, a TRS controller to ECU interface <NUM> connecting the TRS controller <NUM> and the ECU <NUM>, and a starter control <NUM> configured to control a starter <NUM> for initiating an engine startup. In some embodiments, the ECU <NUM> can be a part of an electronically controlled engine (not shown) of a TRS.

The TRS controller to ECU interface <NUM> includes a keyswitch signal connection <NUM> that is configured to send a keyswitch signal from the TRS controller <NUM> to the ECU <NUM>, a run signal connection <NUM> that is configured to send a run signal from the TRS controller <NUM> to the ECU <NUM>, and a CAN (Controller Area Network) communication connection <NUM> that is configured to provide two-way communication between the TRS controller <NUM> and the ECU <NUM>.

The keyswitch signal connection <NUM> is configured to enable the ECU <NUM> for an engine sub-system operation, disable the ECU <NUM>, and to facilitate TRS power management. In one embodiment, the keyswitch signal connection <NUM> can perform the above functions by invoking a high/active logic state and/or a low/inactive logic state. When in the high/active logic state, the keyswitch signal connection <NUM> is configured to enable communication between the TRS controller <NUM> and the electronically controlled engine via the ECU <NUM>. When the keyswitch signal connection <NUM> transitions from the high/active logic state to the low/inactive logic state, the ECU <NUM> is configured to enter a power latch stage prior to completely shutting off. The ECU <NUM> is configured to command a pre-shutdown component calibration and is configured to write data to permanent memory.

The run signal connection <NUM> is configured to, via the ECU <NUM>, prepare the engine for starting, instructing the electronically controlled engine to stop, reinitializing an ECU <NUM> start routine, and managing power consumption of the TRS generally. In one embodiment, the run signal connection <NUM> can perform the above functions by invoking a high/active logic state and/or a low/inactive logic state. When in the high/active logic state, the run signal connection <NUM> is configured to prepare the electronically controlled engine, via the ECU <NUM>, for starting. When the run signal connection <NUM> transitions from the high/active logic state to the low/inactive logic state and the electronically controlled engine is running, the run signal connection <NUM> is configured to instruct the electronically controlled engine, via the ECU <NUM>, to stop. This reduces power consumption of a unit main battery <NUM> while still allowing data communication between the ECU <NUM> and TRS controller <NUM> via the CAN communication connection <NUM>.

The CAN communication connection <NUM> is configured to facilitate communication between the TRS controller <NUM> and the ECU <NUM>. In particular, the CAN communication connection <NUM> is configured to transmit data messages from the TRS controller <NUM> to the ECU <NUM> that include, for example, an engine crank command message, an engine target speed command message, an engine stop request message, etc. Accordingly, the TRS controller <NUM> can instruct the electronically controlled engine, via the ECU <NUM>, to stop via the run signal connection <NUM> or the CAN communication connection <NUM>. The CAN communication connection <NUM> is also configured to transmit data messages from the ECU <NUM> to the TRS controller <NUM> that include, for example, an engine requested speed or speed limit (including message counter and message checksum), an engine crank request limit (including message counter and message checksum), an engine percent load at a current speed, an actual engine percent torque, an engine speed, an engine starter mode, an engine demand percent torque, engine operating information (limit including an engine operating state, message counter and message checksum), engine shutdown information (including engine wait to start lamp information), engine hours and/or revolutions (including engine total hours of operation), fuel consumption (including engine total fuel used), engine temperatures (including an engine coolant temperature, engine fuel temperature, and engine intercooler temperature), engine fluid levels or pressures (including an engine oil level, an engine oil pressure, and an engine coolant level), engine economy information (including an engine fuel rate), ambient conditions (including a barometric pressure and an engine air intake temperature), a keyswitch battery potential, water-in-fuel information, an intercooler fan request, a coolant fan request limit (including message counter and message checksum), active diagnostic messages, previously active diagnostic messages, diagnostics data clear/reset of previously active DTC, freeze frame PG that tells what DTC caused it, test results for premature DTC's, clear diagnostic information for active DTCs, etc..

The ECU <NUM> includes an ECU enable switch <NUM> that is connected to an ECU main relay <NUM> via a pin <NUM>. The ECU main relay <NUM> includes a relay activator <NUM> and contacts 242a and 242b which are closed when the relay activator <NUM> is activated. In one embodiment, the relay activator <NUM> is a relay activator which when provided with current can close the contacts 242a and 242b. The relay activator <NUM> connects to the pin <NUM> at one side and to the unit main battery <NUM> at the other side. The contact 242a connects to pins <NUM> and <NUM> at one end and the contact 242b connects to the unit main battery <NUM> at the other end. The pin <NUM> connects to a circuit (not shown) that is configured to control an amount of power supply from the unit main battery <NUM> to the ECU <NUM> via the pins <NUM> and <NUM>. The unit main battery <NUM> can be, for example, a <NUM> V DC battery that can have a supply voltage up to a maximum voltage, for example, about <NUM> V. The unit main battery <NUM> is configured to supply an amount of power for the TRS <NUM> and a starter <NUM> of an electronically controlled engine. In some embodiments, a battery other than a <NUM> V DC battery can be used.

A supply voltage from the unit main battery <NUM> can be lower than the maximum voltage, for example, when the unit main battery works in extremely cold weather, such as, for example, about -<NUM>°F to <NUM>°F (~ -<NUM> to ~ -<NUM>), has poor battery conditions, etc..

The starter control <NUM> includes a starter relay <NUM> that is configured to control an amount of power supply from the unit main battery <NUM> to the starter <NUM>. The starter relay <NUM> includes a starter relay activator <NUM>, and starter relay contacts 247a and 247b. The starter relay activator <NUM> connects to the contact 242a at one side and to a second switch <NUM> of the ECU <NUM>, via a pin <NUM>, at the other side. The starter relay contact 247a connects to a starter pull-in coil <NUM> of a starter <NUM> and the starter relay contact 247b connects to the unit main battery <NUM>. The pin <NUM> includes circuits configured to control an amount of power supply from the unit main battery <NUM> to the starter relay <NUM>.

The starter <NUM> includes the starter pull-in coil <NUM> that is connected to the starter relay contact 247a and a starter main coil <NUM> connected to the unit main battery <NUM>. The starter <NUM> is powered by the unit main battery <NUM> to initiate engine startup.

The ECU enable switch <NUM> is configured to be closed when the keyswitch signal connection <NUM> sends a keyswitch signal from the TRS controller <NUM> to the ECU <NUM>. When the ECU enable switch <NUM> is closed, current is configured to flow from the unit main battery <NUM> to an internal ECU ground <NUM> through the relay activator <NUM> and the pin <NUM>. The contacts 242a-b are then configured to close, which allows current to flow from the unit main battery <NUM> to the ECU <NUM>, via, for example, the pins <NUM> and <NUM>.

When the TRS controller <NUM> determines that an engine startup is requested, the run signal connection <NUM> is configured to send a run signal from the TRS controller <NUM> to the ECU <NUM> and a run signal voltage potential can be set, for example, from a low-level to a high-level, on one side of the starter relay activator <NUM>. The current does not flow through the pin <NUM> when the second switch <NUM> is open, and the starter relay contacts 247a and 247b are open. In this state, the ECU <NUM> and the engine (not shown) are in pre-crank state where pre-crank functions can be conducted prior to engine crank. When the TRS controller <NUM> receives an instruction to start the engine, the TRS controller <NUM> activates a run relay operation of the TRS controller <NUM> followed by sending the run signal and the engine enters the pre-crank state. The pre-crank functions can include one or more of fuel priming, warning buzzer activation, engine pre-heating, etc..

When the pre-crank functions have been completed, the TRS controller <NUM> can initiate an engine start function by transmitting a CAN message, via the CAN communication connection <NUM>, to the ECU <NUM>. The CAN message includes a crank request (CRRQ) message that contains instructions from the TRS controller <NUM> to the ECU <NUM> to close the second switch <NUM> connected to the pin <NUM>. The starter relay contacts 247a-b are then configured to close to allow the supply of current from the unit main battery <NUM> to the starter pull-in coil <NUM>. In turn, the starter pull-in coil <NUM> engages the starter main coil <NUM> and a cranking of the engine starts. During the cranking, the voltage supplied by the unit main battery <NUM> to the starter <NUM> may fall and rise in a cyclic manner such as, for example, as shown in <FIG>.

<FIG> illustrates a voltage profile supplied to the starter <NUM> by the unit main battery <NUM>. The unit main battery <NUM> has an original voltage of y. During the cranking, the voltage profile oscillates between an upper limit y<NUM> and a lower limit y<NUM> with a period of t<NUM>. The upper limit y<NUM> is lower than the original voltage y. When the supply voltage is below a voltage threshold y<NUM> shown in <FIG> and the TRS controller <NUM> does not instruct the switches <NUM> and <NUM> to remain closed, the switches <NUM> and <NUM> will open. In one example, the original voltage y, the upper limit y<NUM>, the lower limit y<NUM>, the voltage threshold y<NUM>, and the time period t<NUM> are about <NUM> V, about <NUM> V, about <NUM> V, about <NUM>. 5V, and about <NUM> mini-seconds, respectively. It is to be understood that the voltage threshold y<NUM> can vary, for example, from about <NUM> to about <NUM> V. If the switches <NUM> and <NUM> open during the cranking, the ECU <NUM> can lose power and cannot synchronize data, for example, incapable of computing engine speed information from a camshaft and a camshaft sensor, computing engine fueling command instructions, etc. Loss of synchronization can cause an immediate cessation of fueling which stops the engine startup.

The TRS <NUM> shown in <FIG> can improve engine starting performance even when the supply voltage is below a voltage threshold such as, for example, shown in <FIG>. The TRS controller <NUM> allows the unit main battery <NUM> to supply power to the engine starter <NUM> continuously until the electronically controlled engine is completely started. In one embodiment, the TRS controller <NUM> can continuously transmit the CAN message at a first rate to the ECU <NUM>, to keep the keyswitch signal and the run signal active. The first rate can be much faster than the oscillation frequency (e.g., <NUM>/t1 shown in <FIG>) of the voltage profile. In some embodiments, the first rate of transmitting the CAN message can be, for example, about <NUM> (or <NUM> mini-seconds in time period). During intervals of receiving the CAN messages, the ECU <NUM> can be reset. Even if the ECU <NUM> is reset, transmitting the CAN message at the first rate allows the ECU <NUM> to receive the CAN message as soon as the ECU <NUM> completes a reset. This allows the circuits of the pins <NUM> and <NUM> to keep the previous instructions (prior to the reset of the ECU <NUM>) from the TRS controller <NUM> and allows the switches <NUM> and <NUM> to remain in a closed position for a second period of time. The engine can be completely started during the second period of time. It is to be understood that the first rate can be faster or slower than <NUM>, as long as the switches <NUM> and <NUM> can remain closed during the second period of time.

As shown in <FIG>, a voltage profile supplied to the starter <NUM> by the unit main battery <NUM> is lower than the threshold voltage y<NUM> for a first period of time t<NUM>. In one embodiment, the first period of time t<NUM> can be, for example, <NUM> mini-seconds. The portion of the TRS <NUM> is configured to control the switches <NUM> and <NUM> to be closed in the manner as described above. The switches <NUM> and <NUM> are closed for a second period of time so that an amount of power can be continuously supplied to the ECU <NUM> and the starter relay <NUM>, respectively, during the second period of time, and the electronically controlled engine can be started completely. In some embodiments, the second period of time is no less than the first period of time t<NUM>.

<FIG> and <FIG> respectively illustrate schematics of a portion of a TRS <NUM> and a portion of a TRS <NUM> for starting an electronically controlled engine with a low supply voltage, respectively, according to other embodiments.

The TRS <NUM> includes a starter relay <NUM> that is configured to control the startup of a starter and an electronically controlled engine. The starter relay <NUM> includes a starter relay activator <NUM> that connects to a starter relay output <NUM> of a TRS controller <NUM> at one side and to a pin <NUM>' at the other side. That is, the starter relay <NUM> is supplied power by the TRS controller <NUM>, via the starter relay output <NUM>.

The TRS <NUM> includes a starter relay activator <NUM> configured to control the startup of a starter and an electronically controlled engine. The starter relay <NUM> includes a starter relay activator <NUM> that connects to a keyswitch signal connection <NUM> at one side and to the pin <NUM>" at the other side. That is, the starter relay <NUM> is supplied power by the keyswitch signal connection <NUM>.

The embodiments described above in <FIG>, allow the ECU (e.g., the ECU <NUM>) to provide diagnostic information on the starter relay prior to entering into a pre-crank mode (e.g., as soon as a keyswitch signal is activated by a TRU controller).

<FIG> illustrates a flow diagram of a method <NUM> for starting an electronically controlled engine with a lower supply voltage. The method <NUM> is illustrated as performed by the TRS <NUM>. It is to be understood that the method <NUM> can also be performed by other systems for starting an electronically controlled engine with a low supply voltage, such as, for example, the TRS <NUM>, <NUM> as shown in <FIG>.

At <NUM>, the TRS controller <NUM> waits for an instruction to being an engine startup. The method <NUM> then proceeds to <NUM>.

At <NUM>, the TRS controller <NUM> activates a keyswitch signal, via the keyswitch signal connection <NUM>, to close the ECU enable switch <NUM>. Upon the closure of the ECU enable switch <NUM>, the contacts 242a and 242b are closed and the unit main battery <NUM> supplies power to the ECU <NUM>. The method <NUM> then proceeds to <NUM>.

At <NUM>, the TRS controller <NUM> activates a run signal, via the run signal connection <NUM>. The ECU <NUM> and the engine (not shown) are in pre-crank state where pre-crank functions can be conducted prior to engine crank. The method <NUM> then proceeds to <NUM>.

At <NUM>, the TRS controller <NUM> transmits a CAN message, via the CAN communication connection <NUM>, to close the second switch <NUM>. The CAN message includes a crank request (CRRQ) message that contains instructions to the ECU210 to close the switch <NUM> on the pin <NUM>. Current is supplied from the unit main battery <NUM> to flow through the starter relay activator <NUM>, which causes the starter relay contacts 247a-b to close and allows current to be supplied from the unit main battery <NUM> to the starter pull-in coil <NUM>. The starter pull-in coil <NUM>, in turn, engages the starter main coil <NUM> and a cranking of the engine starts. The method <NUM> then proceeds to <NUM>.

At <NUM>, the cranking initiates engine startup. During the cranking, a voltage supplied by the unit main battery <NUM> to the starter <NUM> falls and rises in a cyclical manner as shown in <FIG>. The method <NUM> then proceeds to <NUM>.

At <NUM>, the TRS controller <NUM> determines whether the voltage supplied to the starter <NUM> is below a voltage threshold for a first time period. In one embodiment as shown in <FIG>, the voltage threshold can be about <NUM>. When the supply voltage is below the voltage threshold and the TRS controller <NUM> does not instruct the switches <NUM> and <NUM> to remain closed, the switches <NUM> and <NUM> will open. If the supply voltage is below the voltage threshold, the method <NUM> proceeds to <NUM>. If the voltage is not lower than the voltage threshold, the method <NUM> proceeds to <NUM>.

At <NUM>, when the supply voltage is below the voltage threshold, the TRS controller <NUM> continuously transmits the CAN message at a first rate to the ECU <NUM>, to keep the keyswitch signal and the run signal active. In some embodiments, the first rate of transmitting the CAN message can be about <NUM>. During intervals of receiving the CAN messages, the ECU <NUM> may be reset. Even if the ECU <NUM> is reset, transmitting the CAN message at the first rate allows the ECU <NUM> to receive the CAN message as soon as the ECU <NUM> completes a reset. This allows circuits at the pins <NUM> and <NUM> to keep the previous instructions (prior to the reset of the ECU <NUM>) and the switches <NUM> and <NUM> to remain in a closed position. In some embodiments, the TRS controller <NUM> continuously transmits the CAN message for a second period of time. The second period of time is not shorter than the first period of time during which the supply voltage is lower than the voltage threshold. The method <NUM> then proceeds to <NUM>.

At <NUM>, the TRS controller <NUM> determines whether the engine startup completes. If the engine startup has completed, the method <NUM> proceeds to <NUM>. If the engine startup does not complete, the method <NUM> proceeds to <NUM>.

Claim 1:
A method (<NUM>) of starting an engine including an engine control unit (ECU) (<NUM>) of a transport refrigeration system (TRS) (<NUM>, <NUM>, <NUM>), the method (<NUM>) comprising:
waiting for an instruction to begin an engine startup (<NUM>);
activating a keyswitch signal to close an ECU enable switch (<NUM>) in order to supply power from a battery (<NUM>) to the ECU (<NUM>) upon receiving the instruction to begin engine startup (<NUM>);
activating a run signal, via a TRS controller (<NUM>), to set the ECU (<NUM>) and the engine to a pre-crank state (<NUM>);
transmitting a CAN (Controller Area Network) message, via the TRS controller (<NUM>), to close a second switch (<NUM>) of the ECU (<NUM>) to supply power from the battery (<NUM>) to a starter (<NUM>) to start cranking of the engine (<NUM>);
initiating startup of the engine (<NUM>);
upon initiating startup of the engine, determining whether a voltage supplied to the starter (<NUM>) is below a voltage threshold for a time period (<NUM>); and
when the voltage supplied to the starter (<NUM>) is below the voltage threshold for the time period, the TRS controller (<NUM>) continuously transmitting the CAN message at a predetermined rate to the ECU (<NUM>) to keep the keyswitch signal and the run signal active (<NUM>) until engine startup is complete.