ABS Lamp Illuminates, ABS DTC 0281 May Be Present (Adjust Stoplamp Switch)

Some drivers of the above vehicles may comment about the ABS lamp illuminating. An ABS DTC 0281 - Brake Switch Circuit may have been set (current or in history) on those vehicles equipped with hydraulic brakes. The DTC will be stored in memory and the ABS will be disabled.

A faulty or improperly adjusted stoplamp switch may cause this condition.

The currently installed stoplamp switch may exhibit too much free movement of the actuator arm. The staking on the rivet that forms the pivot axis of the switch controls this free movement. In some cases, the staking action may not have sufficiently closed the rivet. This insufficient rivet staking may cause a light preload on the slider contact points, resulting in intermittent contact and setting a hydraulic ABS DTC 0281. This intermittent contact may also be present on the air ABS stoplamp switch, but may not set a DTC.

Properly adjust the stoplamp switch using the following procedure. If proper adjustment does not resolve the condition, replace the stoplamp switch. Proper adjustment ensures consistent stoplamp switch activation.

1. Depress the brake pedal arm (3) as far as possible.
2. While holding the brake pedal in the depressed position, pull the stoplamp switch (1) adjustment arm (4) fully rearward to the stop.

Important: Use 45 N (10 lb) of force when pulling the brake pedal arm. Measure the force using a force/strain gauge. Completing this step will make the switch contacts close at the very beginning of the pedal stroke.

3. Pull the brake pedal arm upward and rearward.
4. Release the brake pedal arm.
5. Verify proper operation of the stoplamp switch.
6. Connect the Tech 2 and clear all DTCs.

Parts are currently available from GMSPO.

For vehicles repaired under warranty, use: