GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2008 🢒 Malibu 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 DTC P1AB1

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 P1AB1: Starter/Generator Phase U-V-W Current Sensor Overcurrent

Circuit/System Description

The starter/generator control module (SGCM) monitors the phase U/V/W current sensor to detect 3 phase overcurrent and to protect the MOSFET.

Conditions for Running the DTC
    • Engine is running.
    • Wake up signal is ON.

Conditions for Setting the DTC

Over current signal set for 20 ms.

Action Taken When the DTC Sets
    • Stop PWM (MGU shutdown)
    • APM PWM OFF
    • Battery disconnection (disconnect SW on/off)

Conditions for Clearing the DTC

Over current signal not valid

Diagnostic Aids
    • Possible MGU winding short to other winding or short to case
    • Possible FET breakdown or gate driver circuit fault

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. Disconnect the 3-phase cables from the SGCM. Refer to Generator Control Module 3-Phase Cable Assembly Replacement.
  2. Test each of the 3-phase cables individually for a short to ground.
    3. ⇒If any circuit indicates a short to ground , disconnect the 3-phase cables from the MGU.
    ⇒If the short to ground condition is longer present, replace the MGU.
  3. Test each of the 3-phase cables individually for a short to ground.
    4. ⇒If any circuit does not test normal, replace the 3-phase cable assembly.
  4. If all circuits test normal, replace the SGCM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Generator Control Module 3-Phase Cable Assembly Replacement
    •  Generator with Starter Replacement
    •  Control Module References for SGCM replacement, setup, and programming