GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2009 🢒 Sierra Denali 🢒 Diagnostic Navigation 🢒 Vehicle Diagnostic Information 🢒 Charging System Test

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.

Reference Information

Schematic Reference

Starting and Charging Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Charging System Description and Operation

Electrical Information Reference

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

Circuit/System Verification

Engine ON, observe the charge indicator on the instrument panel cluster (IPC) or message in the driver information center (DIC). The charge indicator on the IPC should be turned OFF and the DIC should not display any charging system message.

⇒If the charge indicator is not on the IPC and a charging system message is not displayed on the DIC, refer to Testing for Intermittent Conditions and Poor Connections.
⇒If the charge indicator is ON on the IPC or a charging system message is displayed on the DIC, refer to Circuit/System Testing.

Circuit/System Testing
  1. Ignition ON, verify that no generator or battery current sensor DTCs are set that would cause a charging system concern.
    2. ⇒If DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle.
  2. Ignition OFF, measure the voltage across the battery terminals. The voltage should read 12.0 volts or greater at room temperature.
    3. ⇒If not within the specified value, refer to Battery Inspection/Test.
  3. Connect a carbon pile tester to the battery.
  4. Start the engine and increase the engine speed to 2,500 RPM. Observe the voltage reading on the tester. The voltage should read between 12.6-15.0 volts.
    5. ⇒If not within specified range, replace the generator.
  5. Adjust the carbon pile tester to the specified load test output value, refer to Generator Usage.
    6. ⇒If not within specified value, replace the generator.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Generator Replacement