Circuit/System Testing
WARNING: This page is about a different car, the 2010 GMC Sierra, 2010 GMC Cab & Chassis Sierra, 2010 Chevrolet Silverado, and 2010 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
4.3L Engine
- Verify that a test lamp illuminates between the generator B+ terminal 1 X2 and ground.
- If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
- Ignition OFF, disconnect the X1 harness connector at the generator.
- Ignition ON, test for less than 1 V between the signal circuit terminal 1 and ground.
- If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
- Engine running, test for greater than 3.5 V between the signal circuit terminal 1 and ground.
- If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
- If all circuits test normal, test or replace the generator.
4.8L, 5.3L, 6.0L, 6.2L, or 7.0L Engine
- Verify that a test lamp illuminates between the generator B+ terminal 1 X2 and ground.
- If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
- Ignition OFF, disconnect the X1 harness connector at the generator.
- Ignition ON, test for 4.5-5.5 V between the control circuit terminal 1 and ground.
- If greater than the specified range, test the control circuit for a short to voltage. If the circuit tests normal, replace the ECM.
- If less than the specified range, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal replace the ECM.
- If the circuits test normal, replace the generator.