W124 250 diesel ABS

[television]

I have sent you the ABS papers.

I would clean all fuse holders and multi plugs with a good non drying switch cleaner

 

[EireJames]

Thank you Malcolm, that is very much appreciated

 

[brianbrian]

Hope it works.

 

[EireJames]

After having a look at the ABS info Malcolm kindly sent me and after spending a few days on small trips around town the fog is clearing, sometimes when lightly braking the ABS kicks in just before the car stops, when there is absolutely no chance of the wheel locking up. This is described as being low voltage from the sensor, from feel I think it's the front driver side wheel. Weird though as she did over 100 miles for me without the light coming on. Also the resistance from both front sensors is over the 1000 ohms. Also in the work car park this morning on the gravel I slammed on, ABS worked as it should and no light came on. I treated the N30 box contacts to a good cleaning and also the ABS sensor contacts where they can be opened. At this stage I think I'll just throw her in for the retest, she may or may not behave for the period it's in there.

 

[star]

not bothered to read whole thread, but it seams that your getting an open circuit on the sensor when the wheel is turned, early sensors can be repaired as it is normally the cable between the plug and the sensor end, ie where the cable is attached to the body and mounted to the strut, it flex's with suspension movement and breaks the wire.

 

[EireJames]

Good man, thanks for that, I will have a look at them this evening, it does make sense (speed bumps seem to trigger it, also it comes on every morning as I approach a particular roundabout, significant camber on that part of the road). I think Brian advise me to check them some weeks back but when the resistance was ok I didn't check the cables in the end :Oops:

 

[KOMPRESSIT]

Hi All,

Just joined this forum & apologies if I've posted this in the wrong place, but this thread looked really good for general ABS checks / tests and advice.

My car is a 1996 C230 Kompressor and I have an ABS problem that is driving me mad.
I read through this post with interest hoping that something new for me to try would be mentioned.

ABS light on at standstill (after self check).

Checked so far:
1) Battery output - voltage OK.
2) Replaced the OVP - no change so later returned for refund.
3) Took car to local indie (new OVP still fitted at this stage) to check codes from circular socket - spent 2 hours and still couldn't get his system to work with my car ("turn ignition on" comment displayed on his laptop even tho' ignition was on ). He said my car wiring was faulty !!
4) Resistance checked all 3 sensors - Front Left & Rear was 1100 Ohms, Front Right was O/C - replaced this. Thought that was the fault - but ABS light still on (even after disconnecting battery & turning wheel lock to lock).

Things still to try:
1) replace brake light switch - could brake switch cause the problem if the brake lights work OK?
2) Replace the OVP again ?
3) Start checking voltages at the ABS Controller - any idea where this is ? I can see the ABS pump OK - is the controller part of the pump or is there a seperate controller somewhere?

Any other ideas on this would be appreciated.

Thanks,

 

[Alex Crow]

have you checked the module itself, i have known corroded connectors on a car the same age. it is in your passenger footwell against the bulkhead.

 

[television]

There could be a fault within the ABS pump I think that the tester used was not compatible with the car

 

[KOMPRESSIT]

Thanks Alexander Patient and Television,

I agree with the comment about the tester - I tried to point out to the indie mechanic, that his software mentioned something about 1997 (my car is early 1996). He said that didn't matter and that it should still work, but I have my doubts.

I have been hoping that the pump itself is not faulty !

I will check the controller connections first.
Is it worth trying the brake switch (brake lights work OK) ?

Thanks again.

 

[television]

Thanks Alexander Patient and Television,

I agree with the comment about the tester - I tried to point out to the indie mechanic, that his software mentioned something about 1997 (my car is early 1996). He said that didn't matter and that it should still work, but I have my doubts.

I have been hoping that the pump itself is not faulty !

I will check the controller connections first.
Is it worth trying the brake switch (brake lights work OK) ?

Thanks again.

No the brake light switch fault does not apply to non BAS cars and I do not think that yours has BAS.

The pump need not be expensive to fix if it is that,, the multi plug connector can be soldered up.

The codes are read by a blink code reader

 

[KOMPRESSIT]

Thanks Malcom,

Based on your response - I didn't buy a new brake light switch. I turned the car on just 5 mins ago - ABS light was on, then again based on your response gave the pump a 'shake' from side to side & 'wiggled' the mult-connector - that did the trick. ABS light is now OFF ! Re-started the car 3-4 times, each time ABS light OFF.

(Not sure if the replacement ABS sensor that I fitted needed approx 5-6 engine starts to reset the light - probably more likely to be the pump connection issue).

So it looks like the Front Right sensor was Open circuit, but also had a slight connection issue (either inside the pump, or at the connector). At least if it comes back on again - I know where to focus my efforts.

So a big thanks to all 3 of you : Alexander Patient, Television and Malcolm !

 

[television]

You can unscrew the electric box off the pump 3 times 6mm special headed screws (cant remember the name) and cut the box open and then solder up.. I can always do it for you,,the pump does not have to come off to do this if you can get to the 3 screws

 

[KOMPRESSIT]

Television, Alexander or anyone else that can help :

I have been out of service 4-5 weeks following a hospital operation - now returning to my car to get the ABS sorted. The problem is definately with the connector pins at the ABS controller which you quite rightly thought was the case Television. (I can get the light to come on or go off by moving the connector from side to side).

Thank you for the offer to re-solder Television, but I think I would like to have a go at repairing myself first -I have soldering iron, solder etc. I removed the front part of the module today - the section that the mult-way connector plugs into.

Now I have it on my kitchen table and cannot see how to get inside. I tried prising apart, but no luck, it seems like a sealed unit.

Any help on how to 'seperate' this part would be appreciated - looks like two seperate mouldings, but can't get to seperate - are there 'lugs' that need to be pushed back?

Thanks again.

 

[KOMPRESSIT]

After removing the serated washers and trying to prise the parts apart for about 1/2 hour - success !

The two parts were stuck together with silicone, but eventually managed to seperate without too much damage to either part. Should be able to go back together again without too much visible damage.

Quickly checked the solder joints of the mult-way pins and by using a maginfying glass, there's two that look like the solder could be broken around the base.

So I'll have a go with the soldering iron tomorrow and hoepfully that will resolve the issue.

Thanks