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can bad or failing master cylinder trigger ABS/Tracs light? S70 1998

I had the ABS/Tracs light come on and sent the module out to Vic Rocha for a rebuild. I am not questioning his workmanship due to all the reviews he has received here. So after correctly reinstalling the module, I still get an ABS light. Following his instructions, I also checked for a broken wire(s) at the ABS sensor at the wheel. I made one wire repair. The other wires were not obviously broken. Still have ABS light on.
Here's another brake issue which might be related: When I brake, the car slightly swerves to the left with the steering wheel turning just a bit like it is turning right. It's not alarming as much as it is annoying at this point. The car has had an alignment two months ago. The guide pins for the brakes have also been regreased. I do have to pump the peddle just a little to get the peddle to feel hard once again, though nothing that is something like slamming the peddle to the floor. Does this sound like the brakes need to be bleed or does it sound like the master cylinder is going bad? If it is a bad master cylinder, could this trigger the ABS/Tracs light?
Happy Easter.
George








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can bad or failing master cylinder trigger ABS/Tracs light? S70 1998

George, I had the same problem on the wife's 850. I agree with the responses regarding making sure the calipers are OK and sliding fine. However my problem got down to the control arm bushings. If you can move the control arm with a crow bar/big screw driver it will cause the car to swerve slightly when the brakes are applied. In my case the first application of the brakes would cause the swerve and a quick release plus reapplication of the brakes would set the car straight. I replaced the calipers but the problem persisted until I replaced the control are bushings. What happens is the control arm and therefore the affected wheel moves slightly when the brake is applied. It changes the front end geometry which causes the car to move right or left. The reapplication of the brakes steers the car straight because the shift has already occurred in the front end.

Good luck








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can bad or failing master cylinder trigger ABS/Tracs light? S70 1998

It looks as if I might have two projects on my hands. We've come quite a way from my first post. My thanks to Klaus and tmccabe for your help. Klaus, I will start with your mechanical advice and then go from there. I will post back and give an update.








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can bad or failing master cylinder trigger ABS/Tracs light? S70 1998

You do have 2 projects. The control arm will need to be replaced, so my first argument for the brake cylinder may be mute.

When my caliper died, I could actually 'feel' the good braking wheel do all of the work at high speed stops.

Perhaps in your case, repl of the control arm is all you need. I had a difficult time compressing the caliper piston even with a C clamp.

Klaus
--
My name is Klaus and I am a V ♂ lv ♂ holic








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can bad or failing master cylinder trigger ABS/Tracs light? S70 1998

Two projects are in order: 1) I did the water bottle test again. The passenger side rotor made more steam than the driver's side rotor. So this replicates the first test. What is strange is that last night when I worked on the car, the caliper was easy to depress with the C clamp. I do think that there are braking issues that need to be resolved since the braking is uneven. 2) The bushings on the control arm are weak and the arm moves back and forth with the pressure of a crow bar. So this is a must. Thanks








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can bad or failing master cylinder trigger ABS/Tracs light? S70 1998

Not ABS related. One of your calipers is not clamping as hard as the other. That could be a caliper problem or a little air in the brake line.

I would do a complete flush of the brake fluid first. Use the blue stuff, it is DOT4+, which is what you want and you will know when the new fluid is coming out of the line. Do the rear brakes first, then the front.

If you had one broken ABS line, I suspect you have more problems. Your best bet is to get a computer readout from the dealer - it will give you specific reasons.

BTW, if you work on the car, the ABS will not turn off until you go over 18mph as it does its self check. If it goes out after you pass 20mph, all is good.

Klaus
--
Volvos should be saved from the junk yards, not donated.








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can bad or failing master cylinder trigger ABS/Tracs light? S70 1998

Klaus,
The ABS/Tracs light went out when I drove it. My wire repair must have worked. Thanks for reminding me about driving it.
I did flush the system. Could not find the blue stuff but flushed an entire 32 oz of regular Dot 4 though the system. Motive Brake Bleeder is great for doing this kind of thing. Still get the pulling to the left side, though not as bad.
The pulling to the left happens only in a regular kind of stopping mode but not if I brake harder. It brakes straight on when I do this. I am tempted to go ahead and bleed with blue stuff.
Could a stuck caliper in the rear of the car be the cause of the swaying to the left when braking? I have not checked them yet. The front pads were wearing evenly.

George








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can bad or failing master cylinder trigger ABS/Tracs light? S70 1998

Sticking rear calipers will not make the car change direction, concentrate on the front.

When my left front caliper froze, the car pulled to the right. At high speeds, the right rotor turned red and the braking distance was terrible - only one brake working. At low speeds, no big problem as the rotor remained fairly cool. I did not notice much wear difference in the pads, but that is hard to detect from side to side.

I only found out by removing the left pads and finding the piston almost impossible to push back in, even with a C clamp. You should be able to push the piston in with a pair of channel locks and not much effort.

Do some more homework on your right caliper. Rebuilt calipers are not very expensive, even from Volvo, and it is safety first.

Klaus
--
Volvos should be saved from the junk yards, not donated.








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can bad or failing master cylinder trigger ABS/Tracs light? S70 1998

Klaus,
Definitely confused. I worked on the right (passenger) side brakes. Cleaned and regreased the guide pins, depressed the caliper with C clamp, put it all back together and went for a test drive. It was fine and then started doing the pulling to the left again, though not as bad.
Though I did not do the driver's side, I noticed that the bushing closest to the front of the car on the control arm had the rubber sticking out more on one side of that bushing compared to the bushing on the other side of the control arm. I wish I could describe it better than that. A crowbar could move the control bar just a little. Is this normal? Could this be a part of my problem?
Thanks, George








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can bad or failing master cylinder trigger ABS/Tracs light? S70 1998

Sounds like the control arm bushings are toast. But, that doesn't affect braking. It sounds like the caliper piston is a bit sticky and not engaging.

Make a couple of jard stops and then check the temp of the rotors. Be careful, they get very hot! I like to use a spray bottle of water and judge the amount of steam coming off the rotor before touching anything near the hub area.

Klaus
--
My name is Klaus and I am a V ♂ lv ♂ holic








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can bad or failing master cylinder trigger ABS/Tracs light? S70 1998

The passenger (right side) had more steam. That is the side I just worked on. So you were corrent about the right caliper causing the car to veer to the left when the brakes are applied. Can that caliper piston be loosened up or does it require replacing?








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can bad or failing master cylinder trigger ABS/Tracs light? S70 1998

It depends on your mechanical skills. I didn't consider myself good enough to reem out the piston and trust it, so I went with a rebuild. I also asked a local mechanic to confirm my diagnosis before ordering a replacement.

Before I replaced the caliper, I went in and made sure the brake line nut at the caliper could be loosened. They do get a bit hard. Check the flexible brake line for cracks and replace at the same time, you will be bleeding the lines anyway.

Grease the new slide pns on the caliper before installing, they don't do that at the refurb shop. Autoparts stores sell silicone brake grease in $1 packets, one will do all 4 brakes.

Klaus
--
My name is Klaus and I am a V ♂ lv ♂ holic








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can bad or failing master cylinder trigger ABS/Tracs light? S70 1998

Thanks, Klaus. That is my homework.
What is your opinion of wornout bushings on the control arm? The car seems kind of "floaty" when it pulls to the left.
George








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can bad or failing master cylinder trigger ABS/Tracs light? S70 1998

Brakes first, control arm diagnostics later. Sounds like your 'float' is due to the power steering compensating for the pull.

Klaus
--
Volvos should be saved from the junk yards, not donated.








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can bad or failing master cylinder trigger ABS/Tracs light? S70 1998

Brakes first it is.







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