1992 W124 230TE ABS Problem

[doshbass]

Hi All,

I have just purchesaed a 1992 230TE. I have a permenant ABS light and as expected no ABS. I have trawled through all the posts here regarding ABS and have taken out the front wheel sensors and cleaned them (they reminded me of playing with iron filings and a magent when I was a kid). Unfortunatly this didn't help.

I know that there is a rear sensor on the diff, but from the posts this shoud be left alone for the average DIY mechanic, can anyone confirm this, or could I give it a go?

Secondly, Is there any way to retrieve the diagnostic codes other than via a main dealer, e.g. PC and cable.

The car seems to run and idle well, although it really seems slow to pick up and go, but I guess it is a heavy car with a fairly small engine.

Any suggestions as to how to dignose the fault would be good.

 

[turnipsock]

Do you know how old the front disks are?

I'm not sure that there is a sensor on the diff, but I may be wrong.

 

[television]

The most common faults with ABS are the cables to the front wheels can go open circuit. though many of the fault codes can be read with a simple LED this does not include the ABS and only covers engine managment. Most garages have read out equipment for this, and it does not have to be a MB outlet.
If you find the cost of fixing more than the value of the car, then look on an MOT list to see the time out time for the ABS warning lamp and put a timer onto the Lamp, cost no more than £4.00. Even upto today its still unknown if ABS ever saved a life, but it has reduced small low speed shunts. ABS is not part of the MOT, but the lamp must go out at the correct time

Malcolm

 

[doshbass]

Hi, thanks for the info,

Re the front disks, I have no idea having just bough the car, although they seem pretty good.

Re Open circuit cables, how can this be tested, there didn't seem to be any logical place to put an AVO meter on, and I'm not sure what I should be looking for in teh way of resistance.

Sounds like a trip to a mechanic to read the damn thing.

 

[television]

The wheel bearings themselves are the magnets for the hall effect sensors that count the revs of the wheels, this info goes up to the ABS micro ECU. there is a comparator clock that runs in the ECU should any one of the wheel counts go out, then braking of the other wheels takes place through the high presure pump and modulator.
On many early cars it was possible to unplug the cables to the wheel sensors directly from the ECU, it is a very small signal easily read on a scope. it is easier these days to get someone to do a read out.

malcolm

 

[Smudge]

ABS problem

Try the fuse in the OVP relay next to the battery.This often causes ABS problems and also rough starting/idling

 

[doshbass]

Dear All,

I don't thinkit is the OVP relay as th ecar runs fine, however I would like to check it, but can't work out where it is. Round by the battery I have 3 relays, possibly some are aftermarket for the alarm system.

How can I identify the OVP relay from the others.

 

[television]

Dear All,

I don't thinkit is the OVP relay as th ecar runs fine, however I would like to check it, but can't work out where it is. Round by the battery I have 3 relays, possibly some are aftermarket for the alarm system.

How can I identify the OVP relay from the others.

Your Over voltage relay is the one with the fuse on top,often orange in colour. I think it sits in the center of your car in front of the screen.
Pin 30 is the 12volt input, pin (s) 87 is the output should be 12volt. Since if this component has failed,(most of them have at some point) the idle would be eratic going up to 1.5k.

Malcolm

 

[kth286]

doshbass

It is likely to be a voltage problem as the ABS system is designed to be disabled in the event of low voltage.

Could just be an old battery. Try a known good one (newish) from a friend to check.

Regards

 

[doshbass]

yup tried that one, thanks - Battery is good. I have to concentrate on a power steering pump and new radiator at the moment (self inflicted damage to the latter whilst trying to replace the former GRRRRR). I will get back to the ABS after that

Cheers all