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.
- Turn OFF the ignition for 30 seconds or until the ECM powers down.
- Disconnect the camshaft position (CMP) sensor.
- Turn ON the ignition, with engine OFF and measure the voltage from the 5-volt reference circuit of the CMP sensor to a good ground with a DMM.
- If the voltage measures 4.7-5.2 volts, replace the camshaft position sensor.
- With the DMM still connected to the 5-volt reference circuit, disconnect all other components connected to the 5-volt reference 1, one at a time. Refer to Diagnostic Fault Information above.
- If voltage changes when one of the above components is disconnected, replace the component. Refer to the appropriate replacement procedure.
- Test the 5-volt reference 1 circuits for a short to ground or a short to voltage.
- If no problem was found in the 5-volt reference circuit, replace the ECM.