Circuit/System Testing
WARNING: This page is about a different car, the 2007 GMC Sierra and 2007 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition OFF, disconnect the generator harness connector.
- The ignition ON, engine OFF, connect a test lamp to battery positive voltage and repeatedly probe the generator field duty cycle circuit, harness side while monitoring the GEN-F Terminal Signal Parameter in the data list, it should change from 0 percent to above 95 percent.
- If the GEN-F Terminal Signal parameter was not affected by the test lamp, test the GEN-F Terminal Signal circuit for a short to voltage, short to ground, a high resistance, an open circuit. If the circuit tests normal replace the ECM.
- If the circuit tests normal during the Ignition ON / Run tests, and the ECM parameter changed from 0 percent to above 95 percent replace the generator.