Another W124 ABS problem

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Member
Joined
Jun 29, 2009
Messages
38
Location
Beckenham, Kent
Car
'02 W208 CLK Convertble
Hi guys,

First of all my apologies for posting up yet another thread about this, I know there's quite a few of them because I've been reading through plenty trying to solve my problem.

I've got an intermittent fault with the ABS light coming on, been this way for almost 2 years now but these days seems to be on more than it is off.
The battery light is also faintly lit on the dashboard and I'm not sure if these two issues are connected, as this is also intermittent, and they're not always on together if that makes sense.

I have a feeling that the dim battery warning light might be down to a dying alternator as the car does seem to lose charge after a few short journeys. Originally I thought this would be causing the ABS problem as well, but after a bit of reading up it appears the ABS isn't as sensitive to this as first thought. Plus I believe the ABS was an issue before the battery warning light started coming on.

First of all, I'd like to confirm with you people that I have located the OVP relay which is so commonly the issue.

IMAG0101.jpg


Is this it?

If so, I've checked that 10 amp fuse on top of it, and it's fine. The pins on the relay didn't seem corroded but I gave everything a good dousing of WD-40 anyway. No change unfortunately :dk:.

I still think the OVP could be the problem though. My reasons for this are that I read elsewhere that if it was an issue with one of the sensors, then the ABS light would only come on when the car started moving, mine comes on before the car starts moving.

I also read that an OVP issue can be related to poor idle problems. Now initially I didn't think I had any idle problems, but when I started it today whilst testing the OVP, the revs did dip a tiny bit during idle.....which actually caused the ABS light to turn off! It then came back on shortly after the revs returning to normal(this is all with the car sitting stationary), then the revs dipped again, even lower, the light went off again, but this time stayed off even after the revs returned to normal. I doubt it'll stay this way though.

Like I say, the dipping revs during idle are nothing serious, I hadn't even noticed it before now.

So, from what I've described, does it sound like the OVP is still to blame? If so, how should I go about remedying it? Bare in mind I'm trying to sell this car, but as you can imagine, not getting much interest with this problem! I've read about people re-soldering them, but it seems like a closed unit to me?

And finally, do you think the battery warning light is related? If not, am I probably right in thinking dead alternator?

I've taken a video on my phone of the starting up sequence just in case this throws out any more clues, sorry about the glare where the ABS light is, if you look closely you can see it come on a few seconds after I start the car.



Thanks for looking, and sorry for the essay.
 
Well I had a go at re-soldering the OVP, provided I did infact re-solder the correct relay. It's made no difference. But for some reason I'm still not 100% convinced this isn't where the problem lies. The circuit board didn't look in great shape.

I'm going to try and find one from a breaker, I didn't want to do this because all I have is some strangers word that the relay even worked to begin with, but I don't see what other option I have.
 
hi
Yup that looks like an OVP - and sounds like an OVP problem

good test write up here -

OVP - basic function and test - Benzworld.org - Mercedes-Benz Discussion Forum

The charging light could just be the brushes/diodes, just pop them out of the back of the alternator to check them

Almost exactly what happened with my TE, although mine had a minor parasitic drain as well to help confuse the issue, and the idle issue I had was just down to dirt body

I think new OVP's are still cheap enough to be viable
 
Thanks for the reply Balge.

I sourced a second hand OVP relay from ThreePointedParts, it unfortunately didn't cure the problem. It felt as if the ABS light was off more of the time than before I replaced the relay, but still temperamental either way.

Can't say I didn't try! A guy took the car today for £350, to be dismantled and exported to Africa apparently. Oh well! Hopefully its death will keep other Mercs alive.
 

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