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.

Turn ON the ignition, leaving the engine OFF. Using a scan tool, observe the TR Sw. parameter while selecting each transmission range. The TR Sw. parameter should match each range when selected.
- If the TR Sw. range on the scan tool matches each selected range, test for intermittent conditions.
Inspect the PNP switch assembly and the shift cable for the following conditions:
- If any of the conditions are found, repair or replace as necessary.
  - Damage
  - Loose or missing mounting hardware
  - Proper adjustment-Refer to Park/Neutral Position Switch Replacement
  - Damaged or stretched cable
  - Proper adjustment-Refer to Range Selector Lever Cable Replacement
Using the scan tool, observe the TR Sw. A/B/C/P parameter. The parameter should display LOW/HIGH/HIGH/LOW.
- If the scan tool displays HI for all signal states, repair the open or high resistance in the ground circuit for the PNP switch.
Turn OFF the ignition. Disconnect the PNP switch connector. Turn ON the ignition, leaving the engine OFF. Observe the TR Sw. A/B/C/P parameter on the scan tool. The scan tool should display HI for all TR Sw. signal circuits.
- If any of the TR Sw. A/B/C/P signal circuits do not display HI, test the affected circuit for a short to ground.
Using the J 35616 GM-approved terminal test kit and a DMM, measure the voltage at each TR signal circuit to ground. Each circuit should measure 10-12 volts.
- If the voltage on any of the circuits is less than the specified value, test the affected circuit for an open or high resistance.
- If an open or high resistance is not found, replace the TCM.
Turn OFF the ignition. Leaving the PNP switch disconnected, disconnect the TCM harness connector. Using the J 35616 , measure the resistance between each TR signal circuit and all other TR signal circuits. The resistance should be greater than 10K ohms.
- If the resistance is less than 10K ohms, test for a shorted together condition on the TR signal circuits.
- If all circuits and connections test normal, test the PNP switch.