P1A91

DTC P1A91 or P1A92

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 Descriptors
DTC P1A91
- 14 Volt Power Module Temperature Sensor Circuit Low Voltage

DTC P1A92
- 14 Volt Power Module Temperature Sensor Circuit High Voltage

Circuit/System Description

The auxiliary power module (APM) temperature sensor is used for overheat protection. The thermistor is located on the control board, near the phase APM power MOSFET. The starter/generator control module (SGCM) monitors the APM temperature sensor for the following:

* To detect if the internal APM temperature sensor is shorted low.
* To detect if the internal APM temperature sensor is shorted high.

If one of the above conditions is detected, the SGCM will set the appropriate DTC.

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

P1A91

FET temperature sensor signal for APM is less than 0.2 volts for 1 second.

P1A92

APM temperature sensor output voltage is greater than 4.6 volts (-14°C or 6.8°F) and APM temperature is greater than 55°C (131°F) for 1 second.

Action Taken When the DTC Sets

APM 50 percent maximum current output

Conditions for Clearing the DTC

Normal range for 10 seconds

Diagnostic Aids

P1A91

Possible APM temperature sensor short to ground or open

P1A92

Possible APM temperature sensor short to voltage

Reference Information
Schematic Reference

Hybrid Controls Schematics (Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Starter/Generator Description and Operation (Description and Operation)
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 Verification

Warning

To help avoid personal injury, be careful when working in the vicinity of the generator battery disconnect control module. Internal components will still be live, 36V potential, even when the cover has been opened or removed.

1. With a scan tool, clear the DTC.
2. Ignition OFF, wait 30 seconds.
3. Ignition ON, operate the vehicle within the Conditions for Running the DTC.

• If the DTC resets, replace the SGCM.

Repair Instructions

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

Control Module References (Programming and Relearning)for SGCM replacement, setup, and programming