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.

Ignition OFF, disconnect the harness connector at the outside moisture sensor.
Test for less than 5.0 ohms between the ground circuit terminal 3 and ground.
- If greater than the specified range, test the ground circuit for an open/high resistance.
Ignition ON, verify that a test lamp illuminates between ignition circuit terminal 4 and ground.
- If the test does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
Ignition OFF, connect the harness connector at the outside moisture sensor.
Disconnect the X4 harness connector at the BCM.
Ignition ON, test for 8-10 volts between the signal circuit terminal 18 and ground.
- If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the outside moisture sensor.
- 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 outside moisture sensor.
Ignition ON, test for 4-8.5 volts between the signal circuit terminal 14 and ground.
- If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the outside moisture sensor.
- 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 outside moisture sensor.
If all circuits test normal, replace the BCM.