P0A4B

DTC P0A4B

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 P0A4B
- Starter/Generator Position Sensor Circuit

Circuit/System Description

The motor generator unit (MGU) position sensor is used for determining motor control of the MGU. The motor control consists of the angular position and speed of the MGU. The rotor is bolted on the MGU shaft, the stator is bolted on the MGU bracket and the sensor circuit is soldered on the motor control board in the starter/generator control module (SGCM). The SGCM monitors the position sensor circuit to detect a converter error (loss of speed signal or tracking).

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

R/D converter error (loss of signal or tracking) for 100 ms

Action Taken When the DTC Sets

Stop PWM (MGU shutdown)

Conditions for Clearing the DTC

Clears 30 seconds after cycle wake up signal.

Diagnostic Aids

* Possible internal sensor short to ground, short to voltage or open/high resistance.
* Possible MGU or SGCM fault
* Possible wiring harness short to ground, short to voltage or open/high resistance.

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 Testing

1. Disconnect the MGU X2 and the SGCM X2 connectors. Refer to Generator with Starter Replacement (Service and Repair) and Generator Control Module Replacement (Generator Control Module Replacement).
2. Test the circuits in the SGCM to MGU Terminal Reference Table as indicated below. Also test these circuits for short to ground.

• If any of the circuits are not within specification, check for an open/high resistance or short to ground.

3. Reconnect SGCM connector X2.
4. Test the circuits in the MGU to SGCM Specification Table to ground as indicated below.

• If any of the circuits are not within the specified range, replace the SGCM.

5. Reconnect the MGU X2 connector and disconnect the SGCM X2 connector. Refer to Generator with Starter Replacement (Service and Repair) and Generator Control Module Replacement (Generator Control Module Replacement).
6. Test the circuits in the SGCM to MGU Specification Table as indicated below.

• If all circuits test normal, replace the MGU.













Repair Instructions

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

* Generator with Starter Replacement (Service and Repair) for MGU replacement
* Control Module References (Programming and Relearning) for SGCM replacement, setup, and programming