Circuit/System Testing
WARNING: This page is about a different car, 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.
The 5-volt reference circuit and the switch signal will have to be checked for shorts to ground, opens, high resistance, and shorts to voltage by following the below listed steps.
- Reference the mode switch supply voltage with a scan tool.
- The scan tool should indicate 4.8-5.2 volts. If the scan tool indicates the voltage is within this specification then with a jumper wire short the switch signal circuit pin 12 on the switch to the 5-volt reference circuit pin 11 on the switch. If the mode switch return voltage on the scan tool measures 4.8-5.2 volts then replace the switch.
- If the mode switch return does not read 4.8-5.2 volts check the switch signal circuit and the 5-volt reference circuits for a short to ground, short to voltage, open, or high resistance.
- If no shorts or high resistance are found on the switch signal or 5-volt reference circuits then replace the transfer case shift control module, reprogram, and complete the motor learn procedure.