GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Saturn 🢒 2008 🢒 AURA 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 DTC P1AA7

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 Descriptor

DTC P1AA7: Starter/Generator Field Coil Circuit

Circuit/System Description

The starter/generator control module (SGCM) monitors the motor generator unit (MGU) field coil circuit to monitor the field coil current is within tolerance. If a fault is detected, the DTC will set.

Conditions for Running the DTC

The engine is running.

Conditions for Setting the DTC

Field coil current - command current is greater than 0.5 amp for 1 second.

Action Taken When the DTC Sets

Stop PWM (MGU shutdown)

Conditions for Clearing the DTC

Clears 30 seconds after cycle wakeup signal.

Diagnostic Aids

This DTC can set falsely when vehicle is keyed off. The DTC is type B, so will not set MIL unless it occurs twice in succession. Refer to Powertrain Diagnostic Trouble Code (DTC) Type Definitions The DTC will not store into history until this occurs. If this DTC is only set in history, clear with scan tool.

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 Testing
  1. Verify that the latest service software is installed.
  2. Disconnect harness connector X2 from the SGCM. Refer to Generator Control Module Replacement.
  3. Test for 5-100 ohms resistance between terminals 9 and 12.
    4. ⇒If within the specified range, replace the SGCM.
  4. Disconnect the 7 pin X1 connector at the MGU. Refer to Generator with Starter Replacement.
  5. Test for less than 1 ohm between SGCM connector harness terminal 12 and the MGU X1 connector harness terminal A.
    6. ⇒If greater than the specified value, test the circuit for an open/high resistance.
  6. Test for less than 1 ohm between SGCM connector harness terminal 9 and the MGU X1 connector harness terminal C.
    7. ⇒If greater than the specified value, test the circuit for an open/high resistance.
  7. Test for infinite resistance between SGCM connector harness terminal 9 and terminal 12.
    8. ⇒If less than the specified value, test the circuits for being shorted to each other.
  8. Test for infinite resistance between SGCM connector harness terminal 12 and ground.
    9. ⇒If less than the specified value, test the circuit for short to ground.
  9. Test for infinite resistance between SGCM connector harness terminal 9 and ground.
    10. ⇒If less than the specified value, test the circuit for short to ground.
  10. If the circuits test normal, replace the MGU.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Generator with Starter Replacement
    •  Control Module References for SGCM replacement, setup, and programming