P1A90

DTC P1A90

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) 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
* Blocked coolant passages or low coolant flow can cause this code to set.
* Low Coolant can cause this DTC to set.

Possible internal failure of the temperature sensor

Reference Information
Schematic Reference

Hybrid Controls Schematics (Hybrid Controls Schematics)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Description and Operation

Starter/Generator Description and Operation (Description and Operation)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Scan Tool Reference

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

Circuit/System Verification

Verify that DTC P0A06 or P0A07 is not set.

If any of the DTCs are set, refer to DTC P0A06 or P0A07 (P0A06)

Circuit/System Testing

1. Ignition ON, command the SGCM coolant pump relay ON and OFF with a scan tool. Feel the for the operation of SGCM coolant pump turning on & off.

• If the SGCM coolant pump does not operate refer to DTC P0A06 or P0A07 (P0A06)

2. Ignition ON, command the scan tool SGCM coolant pump relay output control ON.
3. Inspect for proper coolant flow by feeling the SGCM coolant hoses and comparing to a known good vehicle.

• If the coolant flow is low, check for a coolant restriction. If a coolant restriction is not found, replace the SGCM coolant pump.

4. Observe the scan tool SGCM Converter Temperature, SGCM Inverter Temperature, and SGCM Internal Temperature parameters. The SGCM temperature sensor readings should be within 1 °C (33.8 °F) of each other.

• If any temperature sensor reading is greater than the specified range, replace the SGCM.

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