Stop Lamp Circuit Test
WARNING: This page is about a different car, the 2009 GMC Sierra, 2009 GMC Cab & Chassis Sierra, 2009 Chevrolet Silverado, and 2009 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition OFF, disconnect the harnes connector X4 at the BCM.
- Ignition ON, verify a test lamp illuminates between the terminals listed below and ground.
- Terminal 1
- Terminal 2
- Terminal 4
- If the test lamp does not illuminate, test the B+ circuit for an open/high resistance or short to ground.
- Connect the harness connector X4 at the BCM.
- Ignition OFF, disconnect the harness connector at the appropriate stop lamp.
- Test for less than 1 ohm between the ground circuit terminal GRD and ground.
- If greater than the specified range, test the ground circuit for an open/high resistance.
- Connect a test lamp between the stop lamp control circuit terminal MJR and ground.
- Ignition ON, press and release the brake pedal. The test lamp should turn ON and OFF when changing between the commanded states.
- If the test lamp is always ON, test the control circuit for a short to voltage.
- If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance.
- If all circuits test normal, test or replace the appropriate stop lamp.