Circuit/System Testing: Notes

WARNING: This page is about a different car, the 2009 GMC Canyon and 2009 Chevrolet Colorado. However, it is still accessible from the selected car via links, so may be relevant.

Turn Signal Switch Malfunction

Ignition OFF, disconnect the harness connector X204 at the turn signal/multifunction switch.
Test for less than 5 ohms between the ground circuit terminal B9 and ground.
- If greater than the specified range, test the ground circuit for an open/high resistance.
Ignition ON, verify B+ is present between the turn signal switch signal circuit terminal B5 and ground.
- If not the specified value, test the signal circuit terminal B5 for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
If all circuits test normal, test or replace the turn signal/multifunction switch.

Turn Signal Lamp Malfunction

Ignition OFF, disconnect the harness connector at the inoperative turn signal lamp.
Test for less than 5 ohms between the ground circuit terminal G and ground.
- If more than the specified range, test the ground circuit for an open/high resistance.
Connect a test lamp between the control circuit terminal A and ground.
Ignition ON, command the inoperative lamp ON and OFF with a scan tool. The test lamp should turn ON and OFF.
- If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
- If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
If all circuits test normal, test or replace the inoperative bulb.