Component Testing GMC Yukon Denali GMT900

Component Testing

BCM

1. Key OFF. Disconnect the X1 connector at the TCSCS.
2. Using the L-BU probe J 35616-64B, connect a test light between the indicator dimming control circuit, TCSCS harness X1 pin 4 and a good ground.
3. Key ON, engine OFF. When the daylight running lights (DRL) sensor commands the headlights ON, the test light should be dull or OFF. If the test light is bright, test the indicator dimming control circuit for a short to voltage condition. If all circuits and connections test normal, replace the BCM.
4. Place a shop light on the DRL sensor. When the headlights go out the test light should illuminate brightly. If the test light is dull or OFF, test the indicator dimming control circuit for an open/high resistance or short to ground condition. If all circuits and connections test normal, replace the BCM.

TCCM

1. Key OFF. Disconnect the X1 connector at the TCSCS.
2. Key ON, engine OFF.
3. Using the L-BU probe J 35616-64B, test for 4.5-5.5 V between the 5-volt reference circuit, TCSCS harness X1 pin 11 and a good ground. If the voltage is greater than the specified range, test the 5-volt reference circuit for a short to voltage. If all circuits and connections test normal, replace the TCCM. If the voltage is less than the specified range, test the 5-volt reference circuit for an open/high resistance or short to ground. If all circuits and connections test normal, replace the TCCM.
4. Using the L-BU probe J 35616-64B, connect a test light between the 5-volt reference circuit, TCSCS harness X1 pin 11 and a good ground. The test light should illuminate dimly. If the test light does not illuminate, obtain a different test light and repeat step 4.
5. Key OFF. Wait 30 seconds for the TCCM to shut down.
6. Using the L-BU probe J 35616-64B, connect a test light between the TCSCS harness as specified below for the LED control circuit being tested.
7. Key ON, engine OFF.
8. Using the Special Function ability of the scan tool, command the affected LED ON and OFF. The test light should turn ON (dimly) and OFF as commanded. If the test light remains illuminated when commanded OFF, test the affected control circuit for a short to ground. If all circuits and connections test normal, replace the TCCM. If the test light remains OFF when commanded ON, test the affected control circuit for an open/high resistance or short to voltage. If all circuits and connections test normal, replace the TCCM.

TCSCS

1. Using the L-BU probe J 35616-65B, connect the memory saver EL-49741: harness, to the TCSCS as specified below for the LED being tested. Connecting the harness to the opposite pins will not illuminate the LED.
2. Connect a 9 V battery to the memory saver EL-49741: harness.
3. Verify that only the indicator being tested illuminates. If the indicator does not illuminate when tested or the incorrect indicator illuminates, replace the TCSCS.