Mercedes 230w w124 abs light?? Help pls.

[imbck666]

Hi all
i have a mercedes 230e w124 prefacelift 1990.

Never had such a problem before and owned the car for about a year now..

All of a sudden ran into a deep pothole! GRRR! on the motorway which really gave a knock to the car, i didnt see it..
After that the ABS light came on and i dont know why??

I turned the car off then turned it back on then it went away never coming on again, but now every time i go over 60MPH it just comes on??
ABS is working fine, checked the battery voltage which is over 13 volts when car is on so it cant be a low voltage problem..

If im below 60mph it never comes on, but as soon as i hit 60mph the light abs comes on but abs still works no problem..

any suggestions?

Thanks

 

[d w124]

Are all the tyres the same size?

 

[imbck666]

no front ones are 205 45 17. rear tyres are 225 45 17..
why?

 

[imbck666]

??

 

[d w124]

I think that`s your problem.

 

[imbck666]

why though? what has it got to do with the ABS? and abs sensors? any info?

 

[d w124]

Nothing to worry about mate.Is not gona harm your car in any way.

 

[imbck666]

ok thats a relief, but can you tell me why its doing this? whats the cause for it? any info would be help mate, im just trying to understand why its interfering with the abs..
thanks mate.

 

[d w124]

Got the same prob here bro,but i know you can`t do anything unless i put the same tyre all round.I still don`t know what is the cause of it,but i went to my mechanic who is a MERC and BMW man and he told me not to worry.

 

[imbck666]

hmmm very weird.. thanks for all the help bro.. i appriciate your time..
its kinda weird as what has it got to do with tyres.. and yeah it happened after i got the alloys fitted.. very strange.
Could it not be the abs sensors at the front that may need replacing.. maybe for both of us not a coincidence..

and does your abs work fine as well?

 

[d w124]

My mechanic know that on my car is no expence spared and said that the only way to sort it out,is by geting 225 on front to.Been driving like that for months now and never had any problem with brakes abs on anything

 

[imbck666]

thanks for everything mate.. i have peace of mind now

 

[andy_k]

sorry folks but the stuff about tyres being the same front and rear is wrong - they should be as near as possible to the original rolling radius but you can mix and match with different width/profiles withut the ABS light coming on.

First off, an ABS light is an MoT fail so you need to get it sorted.

As it happened when you gave the wheel a harsh impact check that the sensor is still attached, check the balance of the wheel and whether or not it's buckled

 

[imbck666]

Right, thanks for telling me that, I dont mind about the MOT because it passed about 2 weeks ago before I put the alloys on.
As for the Buckle.. how can i check if my wheel has buckled? My balance is perfect, doesnt pull to any side whatsoever.. and ABS light only comes on when i exceed 60mph.. otherwise its never on..
?

 

[andy_k]

pulling to one side isn't balance, it's tracking.

Balance usually creates vibration at certain speeds.

Take the car down to your local tyre centre and get them to check that the wheel is still in shape and that it is balanced properly

 

[imbck666]

I know that its definetly balanced mate because it was vibrating the steering wheel at 70mph the other week when i first got the alloys fitted.. took it back and got them balanced which has stopped now.. No vibration at any speed at all..
As for buckle in the wheel ive taken the wheels off and cant spot any dents, buckles in the wheels at all.. I still believe now that its a faulty ABS sensor..
Thanks for the help though.

 

[imbck666]

any other ideas mate?

 

[grober]

I would also check the OVP relay which feeds the ABS unit. It may be damaged and vibration at over 60mph may be enough to break an already poor connection. The fact the malfunction only occurs over 60 mph does seem to point to wheel/hub/suspension damage sustained by crashing it the pothole. You can't borrow/ swop a set of wheels temporarily to eliminate this?

 

[imbck666]

well i cant borrow a set of wheels as ive paid over £500 for the set.. but i will take the car to mercedes benz chelsea to get it checked over.. thanks for all the help though..
By the way, have you got a picture of the OVP relay and where in the fuse box is it? Is it the long one?

 

[grober]

well i cant borrow a set of wheels as ive paid over £500 for the set.. but i will take the car to mercedes benz chelsea to get it checked over.. thanks for all the help though..
By the way, have you got a picture of the OVP relay and where in the fuse box is it? Is it the long one?

Its not in the fuse/relay box but normally located beside the engine ECU behind the plastic shield behind the battery. It has a fuse on top of it. The fuel pump relay is located in this area also ( will have kickdown and 4 zyl marked on it). If you decide to change the OVP make sure you get the correct replacement as they changed slightly over the years.