Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptors
DTC P1A91: 14 Volt Power Module Temperature Sensor Circuit Low VoltageDTC 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
Connector End View Reference
Description and Operation
Starter/Generator Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
Caution: 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.
- With a scan tool, clear the DTC.
- Ignition OFF, wait 30 seconds.
- 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 after completing the diagnostic procedure.
Control Module References for SGCM replacement, setup, and programming
