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My '05 C2 was getting an ABS/PSM failure warning light on the dash. Everything seemed fine on the car driving it, but noticed sport mode could not be enabled.
Durametric pointed to a failure with the Brake Light Switch. I checked and noticed that my brake lights were not coming on at all.
So heads up if you see an ABS/PSM failure warning, you may have no brake lights!
I searched around - common suggestion is to simply replace the brake light switch. I removed the switch, and found it was very simple to fix. Most likely the electrical contacts just need cleaned with some steel wool or sandpaper and is as good as new.
General steps to fix:
Switch is right behind brake pedal (circled below). Twist the switch 90 degrees, and pull out of mount:
Here is what the switch looks like hanging down after pulling from it's mounting location. Unplug from the wiring harness:
Once you have the switch out, you'll see it opens up pretty easily - small flat head screwdriver or knife and you can pry it open. Inside is a spring you can set aside. Once open, push the plunger in all the way and it'll expose the electrical contacts that are the friction/contact points and clean them (I used steel wool). I also bent out the contacts a bit to try to improve friction. This will be more clear when you have the switch apart in hand and see how it works - it's a simple mechanism:
On the other side of the switch, you can pull the pins out - clean them as well and put back in.
That fixed it for me! Hope this info is helpful if you run across the same problem.
Last edited by maxw; Jul 25, 2020 at 11:48 AM.
Reason: Additional clarification
Very timely, this just happened on the way home from the farmers market today. I will check for brake lights and proceed. Will report back with findings.
Very timely, this just happened on the way home from the farmers market today. I will check for brake lights and proceed. Will report back with findings.
When I tested my brake lights, my wife reported a quick flicker of the brake lights, but generally they were not working correctly or coming on at all. I suppose it depends on the state of the switch, perhaps if there is some contact they'll work intermittently. If i turned the engine off and restarted, the ABS/PSM message would be gone - until I hit the brakes and started moving (seemed to be the behavior). Ideally you'd have something like the Durametric to confirm if there is fault anywhere, but you don't have that ability this is worth a check. Only difficult thing is getting to the switch - it's certainly not comfortable getting to it but it's doable. Good luck hope it turns out to be something simple like this.
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ABS/PSM Light - Brake Light Switch - EASY FIX
