P1A90

DTC P1A90

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 P1A90
- 14 Volt Power Module Temperature Sensor Performance

Circuit/System Description

The starter/generator control module (SGCM) monitors to detect the failure of the auxiliary power module (APM) temperature sensor by comparing the average of the 2 power inverter module (PIM) sensors and subtracting the module temperature to detect a faulty sensor.

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

APM temperature sensor is greater than 55°C (131°F) for 2 seconds.

Action Taken When the DTC Sets

APM 50 percent maximum current output

Conditions for Clearing the DTC

APM temperature returns to normal range for 10 seconds.

Diagnostic Aids

Possible internal failure of the temperature sensor

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

1. Verify the SGCM coolant pump operates.
2. Ignition ON, command the scan tool SGCM coolant pump output control ON and OFF.

• If the SGCM coolant pump does not operate refer to SGCM Coolant Pump Malfunction.

3. Ignition ON, observe the scan tool SGCM temperature sensor parameters.

• If only the one temperature sensor reads high, replace the SGCM.

Circuit/System Testing
SGCM Coolant Pump Malfunction

1. Ignition OFF, disconnect the harness connector at the SGCM coolant pump.
2. Ignition ON, test for B+ between the B+ circuit terminal A and ground.

• If less than the specified value, test the B+ circuit for a short to ground or an open/high resistance.

3. Ignition OFF, connect a test lamp between the B+ circuit terminal A and the control circuit terminal B.
4. Ignition ON, command the SGCM Coolant Pump Relay ON and OFF with a scan tool. The test lamp should turn On and OFF when commanded.

• If the test lamp does not turn ON and OFF when commanded, test the control circuit for an open/high resistance. If the circuit tests normal, replace the SGCM.

5. If all circuits test normal, test or replace the SGCM coolant pump

Repair Instructions

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

* Generator Control Module Coolant Pump Replacement (Generator Control Module Coolant Pump Replacement)
* Control Module References (Programming and Relearning) for SGCM replacement, setup, and programming