P0A37

DTC P0A37

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.



DTC Descriptor
DTC P0A37
- Starter/Generator Temperature Sensor Performance




Circuit/System Description

The starter/generator control module (SGCM) monitors the performance of the motor generator temperature sensor to detect if it is within range of the other temperature sensors, by comparing it to other temperature sensors it controls.


Conditions for Running the DTC

The engine is running.


Conditions for Setting the DTC

Power inverter module (PIM) TEMP 1, PIM TEMP 2, auxiliary power module (APM) TEMP, Board TEMP, motor/generator unit (MGU) TEMP greater than 30°C (80°F) and engine OFF timer greater than 480 minutes of start up.


Action Taken When the DTC Sets

50 percent maximum torque limit


Conditions for Clearing the DTC

Normal range for 10 seconds


Diagnostic Aids

Possible internal failure at temperature sensor


Reference Information
Schematic Reference

Hybrid Controls Schematics ()
Connector End View Reference

Component Connector End Views (Connector Views)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information


Circuit/System Testing

Caution: To help avoid personal injury, additional precautions must be taken prior to working on the generator control module or the generator starter. After removing the 36V battery cables from the generator battery, remove both engine wiring harness connectors from the generator control module. Wait at least 5 minutes and then remove the generator control module cover. Verify voltage levels at all 36V, 12V, and 3-phase connections, are less than 3 volts using a DMM before proceeding.


1. Disconnect harness connector X2 from the SGCM. Refer to Generator Control Module Replacement ().
2. Using the appropriate test adapters, test for 120-125k ohms resistance between terminals 2 and 14.

• If within the specified value, replace the SGCM.

3. Disconnect the 7 pin X1 connector at the MGU. Refer to Generator with Starter Replacement ().
4. Test for less than 1 ohm between SGCM connector harness terminal 2 and the MGU X1 connector harness terminal G.

• If greater than the specified value, repair the open/high resistance.

5. Test for less than 1 ohm between SGCM connector harness terminal 14 and the MGU X1 connector harness terminal F.

• If greater than the specified value, repair the open/high resistance.

6. If both circuits test normal, replace the MGU.



Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Generator with Starter Replacement () for MGU replacement
* Control Module References (Programming and Relearning) for SGCM replacement, setup, and programming