Tech - Daytime Running Lights (DRL) Flicker

Some owners may comment that the daytime running lights (DRL) flicker as the vehicle is driven. This condition may be more noticeable when driving over bumps.

When the vehicle contacts a bump in the road, the parking brake handle bounces and intermittently closes the parking brake handle switch. This causes the DRL to flicker. A park brake cable that is slightly out of adjustment can also aggravate this situation. This creates a slight free play in the park brake handle.

Install a parking brake cable return spring, P/N 15747309, at the transmission end of the cable. Lubricate the lever assembly pivot pin, the slot clevis pin and the parking brake cable-to-transmission clevis pin. Also, verify that the parking brake cable is properly adjusted. Use the following procedure and the part numbers listed below.

1. Block the rear wheels.
2. Verify proper park brake operation.
3. Readjust the park brake cable. Refer to the Park Brake subsection of the appropriate Service Manual.
4. Mark the location of the adjustment clevis at the transmission end of the park brake cable.
5. Remove the cotter pin and the clevis pin. Remove the clevis from the transmission end of the park brake cable.

Important: Do not apply excess lubricant to the park brake lever pivot pin. This may prevent the proper operation of the switch.

6. Apply a light coat of lubricant, P/N 12345718 or the equivalent, to the park brake lever pivot pin and to both the right and the left clevis pin slots in the cab.
7. Apply a light coat of the same lubricant to the park brake cable clevis pin and the lever at the transmission.



8. Slide the new park brake cable return spring P/N 15747309 over the threaded end of the park brake cable.
9. Adjust the clevis to the original marked location. Install the clevis pin and cotter pin.
10. Verify proper park brake operation.

Parts are currently available from GMSPO.

For vehicles repaired under warranty, use: