ABS Advice Please:~

[Bob Meadows]

ABS update: ~
The rings have been changed as previously mentioned; originals looked their age and a straight forward job. All wheel sensors removed & cleaned up etc. The rears proved to be a little stubborn (as fronts) they had been quite dirty at the pickup points.
The ABS module has also been soldered once again at all the points previously recommended in other articles – a couple of points on this that may help others.
A very quick & easy way to remove the four locking washers (takes seconds) is to tap a thin nail/panel pin into the washer gaps i.e. the part that grips the bolt tubes, this will force the washer to break open, you can replace these with new if you wish.
The four bolts can be removed with a 4mm socket- nothing special.
My ABS case had a narrow gap all round as pictured so a broken hacksaw blade is ideal to cut through the sealing lip—caution do not go too far into the unit as you are working very close to the circuit board- the lip is very thin so once the blade enters the unit just move it round the unit very carefully.
You can now separate the two halves with little effort and neatly, this one has a channel (as pictured) containing a rubber gasket, clean this out to take the new RTV sealer.
The electrics plug that fastens to the side of the unit has a flip lid that also forms a locking facility- make sure that it plugs in correctly and that the lid gives a positive lock.
The outcome: ~
All back to normal, once the car had been tested on the road with the speed increased the light self-cancelled!
Hope the above is of help
Regards Bob

[mike19691969]

"The ABS module has also been soldered once again at all the points previously recommended in other articles – a couple of points on this that may help others."

Can anyone point me in the direction of any of these articles on the soldering of the ABS module? I can't seem to find them anywhere just loads of references to them.

1999 v70 t5 with pulsing brake pedal. initial fault code was d/s sensor so changed that and dtc's reset. Since then I have had no lights or DTC's but still the pulsing pedal.

Changed so far
Front and rear discs and pads
both front reluctor rings. rears look fine.

Any pointers welcome.

[SteveSarre]

Hi Mike,

When you say pulsing pedal, is that the type of pulsing when you press on the brakes that people associate with warped rotors, or the buzz that the ABS makes when it kicks in (or self tests) whether you are pushing the brake pedal or not?

If it happens when you press the brakes, and you have fitted new disks, then maybe you didn't clean the hub surfaces before fitting the disks? Did you check hub runout or disk runout?

Steve

[SteveSarre]

PS

This long thread contains lots of useful info about ABS repair
https://www.volvoforums.org.uk/showthread.php?t=7414

Maybe that will help or include links to other articles.
I havent read it all myself.

But dont rush into doing the ABS module unless you are sure about it being the problem.

Steve

[mike19691969]

Thanks Steve that is exactly what I was looking for, though it is a Loooong read. Strange that I couldn't find it in there as I did look. Eyes painted on syndrome.

The pulsing is defo the ABS activating

With the ABS disconnected, i.e. fuse 4 pulled, the brakes work perfectly with no judder or pulsing.

As I am getting no DTC's in Vida I am at a loss to what else it could be having changed all likely culprits, i.e. reluctor rings.

I will double check the resistance at each sensor but don't expect to find anything there.

Failing that I will have a look at the ECU if only to eliminate it as a suspect. I fix phones as a hobby so soldering does not scare me, just wanted to make sure I got all likely points that others had successfully done and your reply has pointed me to it.

I will keep the post updated with my findings.

[pff]

Originally Posted by mike19691969

I fix phones as a hobby so soldering does not scare me.

Getting the lid off the abs ecu is the worst part,I have yet to see it done cleanly.

I had the pulsing abs brake pedal with no warning light but it only got worse until the light eventually came on and ABS disabled itself.
Wasn't the ecu at all, the rust on the knuckle had raised the sensor far away enough from the reluctance ring to stop it working.

Live values from individual sensors via dice is invaluable for diagnostics.

I would have expected a bad joint to store an error, there are only two wires surely a bad joint would register as a sensor missing?

[mike19691969]

Originally Posted by pff

the rust on the knuckle had raised the sensor far away enough from the reluctance ring to stop it working.

Live values from individual sensors via dice is invaluable for diagnostics.

This evening I plugged in Vida and cleared all codes, though I had no ABS related codes stored. As I cleared the codes the ABS light started to flash. went for a drive and the pulsing had stopped but I noticed that the speed trace on FR sensor kept dropping off then recovering. See "capture" pic attached.

Stripped down FR and noticed that there was a fair bit of rust on the mating surface for the sensor so cleaned and refitted. Cleared codes and another drive. Again the ABS light started flashing but FR sensor now showed a constant speed (see "after" pic). on returning to the house the pedal pulsed twice as I turned in but the abs light was still flashing. As I was looking at the data the ABS light must have went out so a went for a longer drive and the sensor was spoton the whole time. However the pedal did pulse on two occasions but the light has stayed off.

I am certainly getting closer. Tomorrow I am going to change the FR sensor ( I have a few donor vehicles) and see if that cures it. That is the sensor that I originally changed and I admit to buying a cheap one.

Fingers crossed.

[Bob Meadows]

Quote: ~ Getting the lid off the abs ecu is the worst part,I have yet to see it done cleanly.
-------------------------------------

If you use the pointed broken end of a hacksaw blade – approx. 1/8” in and around the lid of the box (cutting the glued down lip) then you will have a box without damage & no swearing!
See main post above for further info- works well.
Bob.

[sdg1970]

I noted there appears to be no thread in the technical section regarding the ABS module resoldering repair!?? I'm going to attempt it on my 97 V70r sometime soon, so anyone got a good link with pictures etc?? 🤔

Edited to add: This thread I found is so far the best and I'll attempt it from that https://www.matthewsvolvosite.com/fo...ic.php?t=12651

[mike19691969]

Originally Posted by sdg1970

I noted there appears to be no thread in the technical section regarding the ABS module resoldering repair!?? I'm going to attempt it on my 97 V70r sometime soon, so anyone got a good link with pictures etc?? 🤔

Edited to add: This thread I found is so far the best and I'll attempt it from that https://www.matthewsvolvosite.com/fo...ic.php?t=12651

That is the clearest guide that I found in my search but I hasten to add that I did not need to use it, but it does look pretty comprehensive.