Do it yourself ABS module repair. Topic is solved

Post by **medic5825** » 29 Dec 2012, 21:00

Hi Guys, Kind of new to the forum... Will the DIY also fix my STC in my 99 S70? Right now the abs and tracs is not working, no lights on in the dash but have a feeling they are burned out with the MIL light. Could it just be a wheel sensor causing the problem?

Thanks

horse · Post by **horse** » 31 Dec 2012, 19:52

96- 850 Glt NA sedan w/ tracs.

My ABS dash light is burned out as it doesn't light at key in accessory mode. So I'm not getting a lit ABS warning light.
Tracs off light stays on.

I read ABS codes using Vol-FRC and had an error for the right rear wheel sensor.
I deleted ABS error code and Tracs Off light went off.

Went to drive it and Tracs off light came back on & stays on again.
Drove it about 40 miles and tracs off light went off for few seconds & went back on and stayed on.

I'm thinking this is the infamous ABS module bug and not the rear wheel sensor. ( seems I read this rear sensor error is the common error you get with the module bug???)

Again, no ABS light as it's burned out. But the error shows I would be having the ABS light on if not burned out.

No speedo issues. Everything else great. Runs like a champ and brakes good ( except no ABS pulse as it's off).

Opinions????

Post by **Matty Moo** » 31 Dec 2012, 20:33

Rr pin is almost always the first to go. If it were the sensor ornwiring the light would have come back right away.

horse · Post by **horse** » 31 Dec 2012, 20:57

Matty Moo wrote:Rr pin is almost always the first to go. If it were the sensor ornwiring the light would have come back right away.

Tracs off light did come right back on as soon as I started it and actually drove. Only stayed off until I moved.
Sorry for being a bit dense, but.......
Right Rear Pin?
Do you mean a brake sensor part on rear wheel or a pin on the module board?
I'm not familiar with these "new" ( lol) fancy Volvo wheel pieces.
But I learn fast.

About the ABS error I said I got, in my last post -
I was referring to what I read here--->
http://www.ipdusa.com/blogs/105/top-10- ... v70-models

quote -->
"ABS Control Module Failure -
Many 1993-2000 850, S70, C70 and V70 models can have issues with the ABS control module that can cause the ABS warning lamp to illuminate. The most common cause is related to an internal failure of the module that causes it to erroneously report an error for a faulty right rear wheel sensor. You replace the sensor and fins that you still have the problem!"<---unquote

BTW--> Thanks

Post by **Matty Moo** » 31 Dec 2012, 21:38

The pin on the circuit board inside the module.

horse · Post by **horse** » 01 Jan 2013, 10:08

Matty Moo wrote:The pin on the circuit board inside the module.

OK.....
Thanks man.

I have a bit of experience re-flowing cold soldering on boards in old 70's stereos I screw around with( Sansui's & Pioneers).
I actually have a nice switchable 15/40 w solder gun, one of those solder sucking bulbs and some acid free electronic solder for this pursuit.

Would seem pointless to just re-flow the bad pins without doing everything though.
I'd hate to repair it only to have other pins going bad later.
I may be a bit out of practice for that job . Hate to fry anything.

Guess I need to figure if I should attempt the repair myself or send it up to you.

Do you re-flow everything on your rebuilds, add new resistors etc?
I must admit your core return deal is appealing. Especially as I'm just down in Ohio.

Regardless...... THANK YOU very much for your input.
Happy New Year!

Post by **medic5825** » 03 Jan 2013, 08:18

ok... So I had no lights on in the dash, decided to try to take off the abs module. Ended up not having the proper e5 inverted torx so I plugged everything in and hooked battery back up. When testing at connection on my 99 s70 ( I know the diagrams/systems are different) I got an ohm reading from 4 and 10, 4 and 11, 4 and 17 and 4 and 18. Number 3 was empty. Anyway plugged everything back in and now I have a brake light on in the cluster ( still no STC light). Can the s70 module be re-soldered or do I need to look for another? Also an interesting fact... I tested a pump from a buddies 01 cross country and my ohm meter will beep for continuity, it will not do this for the s70 pump. will the pump/module from the cross country work with the s70?

Thanks Again!

B234R · Post by **B234R** » 05 Jan 2013, 15:06

Matty Moo wrote:It sounds like the module is fine, it's finding a fault after the 2nd self-diagnostic.

1st self diagnostic is a continuity check.
2nd self diagnostic is a pump motor and wheel sensor check.

When you go to the shop, clear the ABS codes out of the unit then drive the car until the light comes back on. Read the codes again and chase the problem from there. Likely there is only going to be one code, and probably from one of the front sensors. I'd be willing to bet it isn't getting a solid reading, you can rule out continuity since it passed that initial stage.

"Control Module-Internal Fault" is the code for a "Bad" module. It won't come up for you though since it's finding a fault after moving, otherwise your light would always be on.

I´m a bit confused, I couldn´t get the codes read in the shop (it seems a good idea to buy a cable to connect the laptop with Vol-FCR demo installed and not depending on shops) but the symptoms look like a problem with the sensors so I tested the sensors wiring putting a multimeter in the connector pins, and the result was good, all sensors were in the range between 900-1380 ohms. So the wiring is well, the sensors are clean, could it be a problem with the rings? the front ones are easy to clean (I used a toothbrush) but I couldn´t get with the brush to the rear ones. Is there a way without taking apart the hub?

I have to take my 850 to its annual inspection this month and the inspectors are getting rather fussy with ABS and airbag lights.

Thanks a lot!

woodchopper · Post by **woodchopper** » 14 Jan 2013, 05:29

Many thanks to everyone for all the work and pictures you have contributed. My ABS light was coming on infrequently. I took it off and apart. I could not see any cracks in the solder using a magnifying glass so I decided to just put it back on without doing anything to it. I sprayed the connectors and the metal tubes that the module slides onto(electrical contact cleaner). After about a month the light came on again. I put a piece between the wiring harness and pump to put pressure on the pins and that seems to have worked, it has been about six months now.
This is on a front wheel drive non turbo, no tracs.

volvobaggen · Post by **volvobaggen** » 15 Jan 2013, 04:43

woodchopper wrote:Many thanks to everyone for all the work and pictures you have contributed. My ABS light was coming on infrequently. I took it off and apart. I could not see any cracks in the solder using a magnifying glass so I decided to just put it back on without doing anything to it. I sprayed the connectors and the metal tubes that the module slides onto(electrical contact cleaner). After about a month the light came on again. I put a piece between the wiring harness and pump to put pressure on the pins and that seems to have worked, it has been about six months now.
This is on a front wheel drive non turbo, no tracs.

You can´t always see a cracked solder joint. Had you spent the time resoldering and reflowing instead of looking for cracks, the problem would have gone away. Jamming stuff behind the box to bend the circuit board is not the way to treat delicate electronics, and your connections are still unreliable.

Do it yourself ABS module repair. Topic is solved

Re: Do it yourself ABS module repair.