c200 [w202 1997] ABS Light does not come on.

[miker1]

Just had an MOT fail on the fact that my ABS light does not come on when I switch on the ignition [only fail point - bah!].

Any ideas why? [bulb gone obviously - but thats hard to get to!]

Cheers

Mike

 

[anyweb]

when you first turn the key look at all the electrics, what should happen is all light's come on in your instrument panel for a few seconds, this way you can see what bulbs are blown,

so if the abs light isnt lighting at all at this point then you must remove the instrument panel

this can be done with tools from mercedes part number is

W 140 589 02 33 00 cost about 20 quid, better to use them than wire coat hangers as some websites will advise you (i tried the coathanger method and they just didnt have the strength to remove the panel)

to remove it, make sure the key is not in the I or II position, ie: car turned OFF. you do not have to remove the steering wheel, just use the tools to extract the panel and wiggle it back and forth over the steering wheel, once it is out you can disconnect the two black cables plugged into the back of the panel, do NOT turn on the car after disconnecting as this will register a FAIL in the SRS circuits,

replace the faulty bulbs and reconnect the two cables, at this point you can turn the key to see does everything light up, it should.

Now re-insert the panel and feel happy that you did it yourself and saved lots of money

the replacement bulbs can be bought from your dealership, or if you are lucky like me, you can simply move the unused bulbs (for options not installed on your car) which are working, to the non working places.

cheers
anyweb

 

[miker1]

Thanks!

So there is not likely to be any more nefarious problems as to why it doesn't light?

Mike

 

[jibcl500]

Does your ABS work??? could be the light was on and the bulb has been removed to hide the fault.

jib

 

[miker1]

I havn't actually tried it in anger

How best to test it SAFELY?

[My MOT man made the same comment - seems I am too naive!]

 

[anyweb]

easy, get a long straight road with no traffic (out in the country somewhere) and one that has some gravel on it, accelerate to 70km/ph and when safe to do so, brake hard and fast,

you should feel the brakes shuddering as the ABS kicks in.

cheers
anyweb

 

[wireman]

Press very hard on the brake pedal whilst in motion, there should be a rapid pulsing feeling back through the pedal and little or no tyre squeal, the car should stop in a straight line without pulling to one side or t'other. Hold the steering gently with both hands for the duration of the test, any tendency to pull will be felt via your fingers.
The rapid automatic release and re-activation of the brakes is somewhat startling to one who has never experienced it, keep your foot hard on the brakes despite the buzzing feedback from the pedal.
There should be no skid marks, on the road at least.

Choose any empty bit of road.

Check your rear view for other vehicles before you test the brakes.

Secure all loose articles before you try this test, especialy those bits that live on the rear seats and parcel shelf.

There may be a thump from the back end just after you stop, if its not some other car having attempted to enter your boot (see above) it will be the spare wheel or jack falling back into place, if you try this on that anti skid stuff at junctions the thump may just be the whole of the rear end falling back onto the road.

Making the brakes do their stuff in anger every once in a while will help keep the brake disk working surfaces in clean condition reducing their tendency to glaze and corrode, a condition that often afflicts the brakes of cars which are infrequently driven hard.

 

[miker1]

Ok - I nice smokescreen later, it is obvious I have no ABS.

So, possible reasons please - oh learned ones.

Oh, if its any help my cruise does not work either - it never has from when I bought it.

 

[television]

You may or may not have an Over voltage protection relay, if you do its 128 in the link and the only relay to have a fuse on top.

You must check to see if the bulb in the cluster has been removed to hide the fault before you bought the car

http://www.detali.ru/cat/oem_mb2.as...417717.418&CT=F&cat=44V&SID=54&SGR=045&SGN=03

 

[miker1]

****** Hell!!

No effing bulb in there.

According to garage 3 probs shown up on the readout;

ABS pump duff;

ABS Rear N/S sensor and to cap it all

There is a wiring prob - the ABS light stays on even with the key out.

Aside from driving into a tree - anyone got any suggestions of fixes and/or likely costs?

Or to put it another way HELP!!!!

 

[BlackC55]

I suspect the control unit is back feeding somehow.

It needs some time spent on it.

 

[television]

You ABS lamp is driven from a pressure switch within the ABS pump and it looks as though someone has been playing with the wires, this would also account for the pump showing up as faulty

 

[miker1]

You ABS lamp is driven from a pressure switch within the ABS pump and it looks as though someone has been playing with the wires, this would also account for the pump showing up as faulty

Thanks for these responses folks.

My ABS unit is a combined pump and control - Dronsfields has one for £100+vat+del.

Television, would I be right in thinking that as the ABS light is on, even when the key is out, it is most likely some form of short? [as the ABS unit would not be communicating when switched off]

If so, is there any sparks here who could suggest how I could find this possible fault?

 

[television]

Your car has been messed around with and this makes it hard. Has someone done a bodge in the cluster do you have a volt meter, if so so will need to remove any live feed that goes to the pump, if the light stays on then the cluster has been interfered with

 

[bigasotonuk]

Hi,
I would of thought the light should go out regardless of fault with the ignition off.
I personnally would fit the ABS Unit and clean/replace wheel sensor first, before worrying about the warning light as i reckon your warning light fault will clear with the replacement of the ABS Unit.

 

[television]

Hi,

before worrying about the warning light as i reckon your warning light fault will clear with the replacement of the ABS Unit.

It cant do that as the pressure switch is fed from the pump, the pump is fed from the ign switch, so I know that the wires have been moved

 

[BlackC55]

You really need a wiring diagram and a good fault reader etc to start this one. It is no good just bolting stuff on until it fixes it. Start from the begining and work through it. If it is beyond you get a specialist to look at it or an auto elec.

 

[television]

You really need a wiring diagram and a good fault reader etc to start this one. It is no good just bolting stuff on until it fixes it. Start from the begining and work through it. If it is beyond you get a specialist to look at it or an auto elec.

I think that Black is right on this, either that or you need a car to copy

 

[miker1]

Hi,
I would of thought the light should go out regardless of fault with the ignition off.
I personnally would fit the ABS Unit and clean/replace wheel sensor first....

Thats the $million point [ and with Merc that amounts not too far off]. The damn light IS on all the time!

Oh for the odd million.....:roll:

 

[miker1]

You really need a wiring diagram and a good fault reader etc to start this one. It is no good just bolting stuff on until it fixes it. Start from the begining and work through it. If it is beyond you get a specialist to look at it or an auto elec.

It is WAAY beyond me!:-(

You reckon an auto-leccie would be a good bet?

I know its a "piece of string" question, but how long would you think a good electrician would take to fault check the cluster?