When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
ABS and ASR warnings on, CC inoperative – your stop light switch may be faulty
MY1993 500SL; Cruise Control occasionally dropped and ASR and ABS lights turned on. The MIL lights went off after restart. Diagnostics reported stop lamp switch DTC. I fixed the switch with contact cleaner.
The problem went almost away but rarely repeated. After a couple of years, same fault reoccurred but restart did not help. Now ABS/ASR system had three nasty trouble codes #13 (stop lamp switch), #15 (ABS/ASR Module) and #33 (CAN data line short or open circuit). Cruise Control threw again #5 (stop lamp switch). The problem was solved with new brake light switch.
Stop lamp switch has two connectors. You can open it but two contact breakers are difficult to access for cleaning. A new switch is not expensive. The original part # is A 000 545 99 09.
To access the stop lamp switch, you need to remove panels under the dash, driver side. The switch is a tight fit near the brake pedal pivot. Detach two wire connectors (with snap locks). The switch has a snap peg on left side you need to push and then turn the switch in order to remove it.
Probably, bad stop light switch is an increasingly common issue in our three decades old cars.
08-08-2021, 03:44 AM
