ABS module and brake noise

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Michael - 26 Sep 2005 15:37 GMT

I've been driving with an intermttent ABS module for over a month and lately
my brakes have been squeaking pretty bad when cold.

Yet, I know the pads and rotors are nearly knew and the noise wasn't there
before tha ABS problem.

Does the ABS failure actually play havoc with the pads and rotors?

Thanks. (1998 S70 T5)

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Randy G. - 26 Sep 2005 16:28 GMT

>I've been driving with an intermttent ABS module for over a month and lately
>my brakes have been squeaking pretty bad when cold.
[quoted text clipped - 3 lines]
>
>Does the ABS failure actually play havoc with the pads and rotors?

Generally, an ABS failure should just shut down the ABS so that it
doesn't operate- thus the warning light telling you that it is not
operating.

How many miles since the last service? Often, an ABS failure is caused
by dirty wheel sensors. They have powerful permanent magnets in the,m
and they pick up lots of metallic particles and eventually they cannot
deliver the correct signal. Removing them and just giving them a good
cleaning to remove the particles usually does the trick. Use gloves
and a disposable rag to wipe them down. Remove them carefully without
stressing their attached wiring.

What is "nearly new"? Squeaky brakes can be caused by a lot of things:
- pads were not broken in properly
- anti-squeal parts were not used
- poor combination of rotor and pads
- corroded and or sticking caliper piston(s)

__ __
Randy & \ \/ /alerie's
\__/olvos
'90 245 Estate - '93 965 Estate
"Shelby" & "Kate"

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Michael - 26 Sep 2005 17:46 GMT

Thanks Randy.

I'm in electronics and thought I'd look at the module myself time
permitting.....and the sensors as well.

Perhaps I'm having a caliper problem ? (Pads and rotors are near new).

Just noticed today, they only squeak when cold and after several brakings,
no noise at all.

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Randy G. - 26 Sep 2005 20:09 GMT

Volvo brakes, deservedly or not, have over the years gained a
reputation for squeaking. The appliaction of what is commonly referred
to as "brake grease" [a noise reduction goo that is applied to the
bakck of the pads and allowed to dry before installation] or the use
of the anti-squeal brkae shims (a Volvo part) will reduce this to just
about zero.

If the ABS light comes on intermittantly, definitely clean the sensors
first. There is a fellow in So. California that rebuilds the ABS
computers with upgraded parts for a reasonable price, and he tests
them personally and guarantees his work. I can't find the link.

You might also find some useful info here:
http://www.brickboard.com/FAQ/700-900/BrakesABS.htm#ABSDiagnosticCodeRetrieval

>Thanks Randy.
>
[quoted text clipped - 5 lines]
>Just noticed today, they only squeak when cold and after several brakings,
>no noise at all.

__ __
Randy & \ \/ /alerie's
\__/olvos
'90 245 Estate - '93 965 Estate
"Shelby" & "Kate"

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Michael - 27 Sep 2005 18:43 GMT

Randy,

If the ABS module is bad, would the ABS/TRACS indicators come on when I
turned the ignition switch on?
(Not start, just on).

Also, where are the ABS wheel sensors exactly?
Same for front and rear?

Thought I'd get down there and clean.

Thanks.

--Mike

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Randy G. - 27 Sep 2005 19:30 GMT

>Randy,
>
[quoted text clipped - 6 lines]
>
>Thought I'd get down there and clean.

I believe that [nearly?] all warning lights should come on with the
ignition key in P-1. After starting the car, the lights should go out
(all lights should go out with the exception of the parking brake
warning light until the bake is released, and the seat belt warning
light depending on how it works in that car).

The front wheels each have a sensor mounted in the hub, accessed from
under the car, or remove the wheel to see it a bit more easily. It is
the only electrical sensor on the front wheels as it should be easy to
spot. It should be held by a single bolt- like T-10 torx or something
like that. The rear might use the speedo sender in the diff or such- I
don't know that car specifically, but I could not find a listing for a
separate ABS sensor part in the Vadis for that car, although I had to
guess at the particulars only having the year and model to go by.

use care when wiping off the metallic crud becasue the little
splinters easily penetrate skin and they hurt.

__ __
Randy & \ \/ /alerie's
\__/olvos
'90 245 Estate - '93 965 Estate
"Shelby" & "Kate"

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Mike F - 28 Sep 2005 13:27 GMT

> >Randy,
> >
[quoted text clipped - 30 lines]
> '90 245 Estate - '93 965 Estate
> "Shelby" & "Kate"

For this car (98 S70), there are sensors at each rear wheel, joined to a
common harness that goes over the gas tank.

Signature

Mike F.
Thornhill (near Toronto), Ont.

Replace tt with t (twice!) and remove parentheses to email me directly.
(But I check the newsgroup more often than this email address.)

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