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.
- Ignition OFF, transmission in Park or Neutral, disconnect the transmission 20-way connector.
- Test for less than 1 ohm of resistance between the Park/Neutral signal circuit terminal R on the transmission side and ground.
- If greater than the specified range, test the signal circuit between the connector and the IMS for an open/high resistance. If the circuit tests normal, replace the IMS.
- Ignition On, verify the Park/Neutral parameter displays In-gear.
- If not the specified value, test the signal circuit for a short to ground. If the circuit tests normal, replace the ECM.
- Install a fused jumper between the signal circuit and ground. Verify the Park/Neutral parameter displays Park/Neutral.
- If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.