GM Service Manual Online
For 1990-2009 cars only

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 P1A6D: Starter/Generator Control Module System Voltage Low

DTC P1A6E: Starter/Generator Control Module System Voltage High

Circuit/System Description

The starter/generator control module (SGCM) monitors the system voltage sensor to detect for a shorted low or shorted high condition.

Conditions for Running the DTC

P1A6D, P1A6E

    • The engine is running.
    • Hybrid mode is active.

Conditions for Setting the DTC

P1A6D

    • Sensor output voltage is less than 0.2 volt (30.0 volts).
    • The 12-volt power supply - 12-volt output voltage is greater than 5 volts for 0.5 ms.

P1A6D

    • Sensor output voltage is greater than 3.84 volt (1.56 volts).
    • The 12-volt power supply - 12-volt output voltage is greater than 5 volts for 0.5 ms.

Action Taken When the DTC Sets

Hybrid system is disabled.

Conditions for Clearing the DTC

Wake up signal is ON.

Reference Information

Schematic Reference

Hybrid Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Starter/Generator Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

P1A6D, P1A6E

  1. With a scan tool, clear the DTC.
  2. Ignition OFF, wait 30 seconds.
  3. Ignition ON, operate the vehicle within the Conditions for Running the DTC and verify the DTC does not reset.
  4. 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