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 APM temperature sensor is shorted low. |
| • | To detect if the 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 volt 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
P1A91, P1A92
APM 50 percent maximum current output
Conditions for Clearing the DTC
P1A91, P1A92
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
Hybrid Controls Connector End Views
Electrical Information Reference
Scan Tool Reference
Circuit/System Verification
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.
P1A91, P1A92
- If DTC is history, refer to Testing for Intermittent Conditions and Poor Connections .
- If DTC is current, replace the SGCM.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for SGCM replacement, setup, and programming
