Hello everyone, I have been trying to solve a problem with my 2005 Volvo xc70, and I have a bit lost. While driving down the road, I heard a clunk under the car then my ABS system failure lights all came on. Less than 100 feet down the road, my check engine light came on. However, to my amazment all the codes cleared on their own a few hours later, which made things worse for my diagnosis. Now The car is driving well, EXCEPT the front right caliper wont fully decompress. After driving my car for a little while, I went out to check my calipers and they all seem fine except for front right passenger. That caliper is very hot its its obvious there is a lot of friction from brake pad. I took my car to the "Discount mechanic shop down the road", and he said I needed all new calipers, breaks, and pads.That made no sense, but to save money I tried replaing that front right caliper and it did absolutely nothing. I cant figure out why passenger caliper wont decompress. I desperately need this fixed so I can get back to work. I suppose I could just keep replacing Rotar and breaks every couple of weeks until I can afford to bring it to a real mechanic. any ideas on what this could be?

Thanks so much in advance

 

What are you using to read your codes? What codes did/do you have?

 

at first I got ABS break system failure. However, somehow the codes cleared by themselves and now there are no codes at all.

 

Some cars have problems with the CEM. They can overheat and cause really strange problems. Most common during hot climates - but, very weird things happen when the CEM overheats. So - using a compatible scanner, what codes are stored in every control unit? (using as scanner that's not just an OBD scanner)

 

I took my car to a mechanic up the road, but he told me he could not read any codes without an error. This guy seemed like a low quality mechanic shop so im not surprised if he was full of crap. I called around and every other shop was at least 2 weeks out on appointments. This guys shop was called " Above and Beyond auto mechanic". I dont have a lot of extra cash right now so I cant afford to go from shop to shop in search of answers. I'm praying someone on here is a wiz and has seen this issue before

 

If you have an Autozone etc near you, see if they will rent/loan an OBD2 code reader (around here its free) capable of reading ABS codes (ie "chassis" codes).

As to the reason for your caliper not getting fluid, the likely cause is the ABS valve body or possibly the controller board. The way the ABS works is when the computer senses one of the wheels has locked up, it uses the valve body to toggle the pressure on/off to the wheels to allow them to slowly rotate and maintain control. If one of the valves to a wheel gets stuck in the off position - the pressure goes to the other wheel which may cause it to lock up prematurely. Remember cars have a dual diagonal braking design where the right front is on the same "circuit" as the left rear so you should check what's goind on the the opposite corner.

regarding the ABS controller board being a possible cause - check out a few sites that repair the boards including: Xemodex, Midwest ABS and Rocha-tec. There should be some content on those sites on how to do a self diagnosis.

 

Thanks for the input. After much research, I was also highly considering the problem to be a valve. You just validated my suspicion. I grealy appreciate your input and thanks for taking the time to help