Hello All,
On my way into work today, I noticed something strange. My amber brake light came on along with a blinking red park light. The braking at first appeared normal but I pulled over and check the fluid. Brake fluid appears full and I restarted the car. Warning went away. About 5 mins later it came back but this time when I attempted braking the car felt like it was getting a flat tire in the front passenger side. I pulled over and thought for sure it was a flat. All tires were fine and I checked brake fluid level again. All good. I started the car and it drove fine, no issues. The only thing I can think was the section of road that I drove over was a little tougher but the area where it felt like I had a flat was smooth so I'm not sure if it rattled some suspension loose and my stopping resettled it or if a fault with the braking or off-road software is causing weird braking. Any thoughts or suggestions on where to start? I also scanned and found no faults. I am aware the electric parking brake does not work.
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I'll help you out... Check the guide pins on the break calipers to make sure they slide in/out easily. I've had some freeze up before. Another symptom of seized guide pins is uneven wear on the inside vs. outside break pad. The outside pad will be thicker if it's not getting pressed into the rotor. If the guide pin is difficult to remove, put an open ended wrench behind the collar and beat the wrench with a hammer. Temp fix is to wire brush off any old burnt grease/rust off the guide pin and caliper mating surface, then regrease and reinstall until you can get a new pin. I rolled up some fine-ish grit sandpaper into a tube and used it to clean up the caliper hole, then blew it out with compressed air.

Rockauto sells new guide pin kits for about $5 so it's good insurance given how heavy these cars are and how easy it is to fix during a brake job. If your brake pads are uneven, you should swap those out and check the rotors to make sure the brakes are aligned with the rotors.

 

Thanks for the suggestions. Any idea if this would throw a brake warning light while driving? I plan to do a brake fluid flush next and inspect everything. I'm wondering if there is an issue with my anti lock braking module as I have heard these can fail but my scan tool shows no faults. I'm also curious if there is a scan tool that will give me more information than mine for brake lights.

 

Nothing you describe sounds like an anti lock braking issue to me. It really doesn't sound like a brake fluid issue to me either, although a flush is never a bad thing. I cannot recall if the parking brake light turns on when the brake wear sensor grounds, but if it were me I would closely inspect that too. Brakes get hot and the plastic tip of the brake wear sensor can crumble. It's rare, but also possible that the brake pad delaminated from the backing and knocked your brake sensor or parking brake cable. Dunno, but would suggest pulling off the wheel on the corner you had issues with and poking around.

 

Thanks for the reply. I ended up changing the brake warning sensor on the rear, and replacing the emergency brake system which was throwing a fault. I also noticed both rear brake lines were corroded so I replaced both. So far warning went away and all is good. I will keep this tread posted if it comes back. Big job overall.