Circuit/System Testing
WARNING: This page is about a different car, the 2008 GMC Sierra, 2008 GMC Cab & Chassis Sierra, 2008 Chevrolet Silverado, and 2008 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
- Engine running, accessories OFF, measure and record the battery voltage at the battery terminals. The voltage should be between 12.6 and 15.0 volts.
- If not within the specified range, refer to Charging System Test .
- Ignition OFF, disconnect the harness connector at the TDM. Refer to Theft Deterrent Module Replacement .
- Ignition OFF, test for less than 5 ohms between the ground circuit terminal 3 and ground.
- If greater than the specified range, test the ground circuit for an open/high resistance.
- Verify that a test lamp illuminates between the B+ circuit terminal 1 and ground.
- If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
- If all circuits tests normal, replace the TDM.