Circuit/System Testing
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2008 GMC Yukon XL, 2008 GMC Yukon, 2008 Chevrolet Tahoe, 2008 Chevrolet Suburban, and 2008 Chevrolet Avalanche. 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 connectors at the ECM.
- Ignition OFF and scan tool disconnected, open and close the driver door, and wait 1 minute. Test for less than 5 ohms of resistance between the ground circuit terminal 73 X1 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 20 X1 and ground.
- If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
- Install a 3A jumper wire between the PWR/TRN relay control circuit terminal 59 X1 and ground.
- Ignition ON, verify that a test lamp illuminates between the ignition circuit terminals listed below and ground.
- Terminal 19 X1
- Terminal 47 X1
- If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.
- If all circuits test normal, replace the ECM.