2004 S80 T6, 136k

My suspicion is the ABS module, but I'm looking for additional opinions.

Driving home this evening, I all of a sudden lost full use of my brakes. Braking as expected for the first 15% of so of the brake pedal depression, utterly useless for the next 70%, and minimal braking for the final push to the floor. Slamming on the brakes was no better.

After a few moments, the "Service Anti-Skid" message appeared, but there were no other warnings. Didn't go far enough to check if the ODO or cruise were working, as I had just made it home and have no intention of putting on miles now. Ran it up and down the street a few times to see if it was something fluky, but the conditions prevailed.

If my little bit of research is correct, I can't just resolder the connections in the ABS module like an older Volvo. I also can't just replace it with a used identical model due to stealership programming. So if it's the ABS module, that leaves me with a significant bill to get it replaced, or a not as significant bill for repair.

But I have no idea how to identify if it's NOT the ABS module (and hopefully something cheaper to fix). Any thoughts? I'll be pulling the ABS module out tomorrow either way in preparation for the inevitable (suggestions for repair places?)

Thanks!

 

I have had my ABS sensor rebuilt twice. Both from Victor Rocha.

Volvo ABS Problems

The first time I replaced it, there was a "Brake Failure, stop safely ASAP" error message. No mechanical symptoms.

The second time, I had error messages come up and the transmission acted terribly.

Both times, the car runs fine while having the module rebuilt. No odometer and spedo, as I disconnected the ABS module fuse while it was not installed in the car.

I also, rebuilt me brake pedal position sensor unit. With that failure, there was not a code in ODBII, just an "Engine Service Required" message. The mechanical failure was the cruise control not working.

Happy to answer any follow up questions, just let me know.

 

I noticed you saying you rebuilt the pedal position sensor ,
how do you do this ,and how simple is this ?
Thank you

 

Moderately easy. You just need to know how to do it.

You need to have basic soldering skills and not much else but a screwdriver.

Fist step is to release the vacuum in the booster. On my '99 S80 T6, there is a hose with a grommet end that attaches to the booster (on the driver's side). I used a large screwdriver to pry open the connection and let air into the system. Releasing the vacuum makes it easier to pull the pedal position sensor out and also it helps prevent the O-ring on the sensor from getting sucked in during removal.

Once you find it, there is a circle clip holding it in that needs to be removed. I think I used small screwdriver.

I was very careful dissecting the assembly using a sharp utility knife. Upon opening, you should see the problem connections that need to be soldered. I used a tiny bit of flux in addition to some good silver solder. Once fixed, I sealed the whole thing with silicone and when dry, electrical tape.

Reverse installation and you should be good to go. Make sure you pump your brake a few times to de-pressurize your booster. I believe it took an electrical re-set to get rid of the warning message. (key on-off five times)

 

hello can i get help with random brake problem, brakes work great almost allways , but like once a month they do not work at all in reverse , then when going forward . till i proceed about 60 feet then work great ???

 

Thank you for the info naperboiler , I will check it out ,but I did find a new replacement
online for about $60 ,so for that price I will buy , but will try to repair original .....

As for b_ruehle that's a rather odd issue you're having,
are there any warning lights or messages in the drivers information display?
and if you do get your car scanned make sure that it's done by a reader that's
able to communicate with Volvo's other modules (ABS, CEM , ECM,ect.)
icarsoft makes one and sells for around $120

hope this helps

Erik

 

I found a ABS unit on Ebay for 190.00 .

 

Just curious, How does engine run. Higher than normal idle?
Could be as simple as a bad vacuum leak at brake vacuum booster