Mercedes-Benz W163 ABS, ETS and BAS/ESP lights on: wiring harness or pump
W163: why are the ABS, ETS and BAS/ESP lights on at the same time?
The cause is often the rear ABS wiring harness, which has chafed through against the body, or worn brushes in the ABS pump motor. A wiring harness fault is typical for this model. Cruise control and the speedometer may also stop working at the same time.
Where does the W163 ABS wiring harness usually chafe?
At the rear, the wires run down from the body towards the brakes, and they chafe at the grommet, the seam of the wheel arch panel or the body near the rear wheel housing. Symptoms often appear randomly in wet weather and get worse over time. The start of the harness leaving the ABS pump is also worth checking.
How is an ABS light fault fixed on a W163?
If the wires are broken, the harness is repaired and the wear point is protected so that it does not chafe again. If the harness is fine, the ABS pump's voltage supply and the brushes are examined, and the brushes are replaced with new ones. The brakes are a safety-critical system, so have a workshop check the result.