Advice please - W124 ABS warning light and OTG problems

[mccrackenj]

Hi all

The ABS warning light has started playing up, i.e. not going off after starting the car. If I switch ignition off and then re-start it behaves itself, i.e. goes off after a few secs. Any ideas? Is this likely to be something simple or should I prepare to get the wallet out?

Also - the OTG has just failed. It gave a weird reading of over 50C then, next time I used the car, it just failed completely. Only a small thing but I'd like everything on this car to be just right. Any ideas?

Car is 1996 E320T

Cheers all

[r129sl]

First off, they are completely separate systems so it is unlikely that the two issues are connected.

The OTG is very simple. There is the headunit, a simple loom, and a sensor behind the number plate. It sounds to me like the sensor has gone AWOL. The sensor is part number A0015422618 and costs about £55 new. You can probably get one at a breaker (I know where there is one close to me but I doubt I will have time to get it off the car any time soon). The sender includes a long wire and plugs into the loom up near the fuse box, a bit of a bugger.

The ABS light is most likely to be a bad front wheel speed sensor. New ones cost about £80. A competent DIYer could fit it himself; a dealer will charge about £80. I don't know how you identify which one it is (i.e. left or right), I can ask my mechanic when I see him later. It may be a matter of trial and error. It could even just be dirty, especially if your car is being put into use after a long dormant period.

[mccrackenj]

Thanks for that Jonathan, really appreciate it.

So, if I'm lucky probably only a couple of hundred quid at the Merc specialist to get both things sorted. I'll be booking it in with him soon for a service and a good poke about anyway.

[mbtech01]

Abs light coming on could also be related to the overvoltage relay that is situated behind the battery in the engine compartment. If you look at the battery there will be a black plastic cover sitting behind it. Just pull it out & you'll see a relay that has a fuse sat in the top of it behind the cover. These relay are a common problem & will cause the ABS system to fail & bring the light on. I've done a couple in recent months for the same problem. They're available from either Mercedes or EurocarParts depending upon your budget.

[mccrackenj]

Have driven it twice more since and the ABS light is behaving itself. I'll try to use it more often over the next couple of weeks and see what happens.

This evening I have been repainting both door mirror housings, to cure some moderate stone chip 'rash'.

[r129sl]

If it is intermittent, I suspect it is an ABS sensor.

[mccrackenj]

r129sl said:

If it is intermittent, I suspect it is an ABS sensor.

Let's hope so. A new sensor and fitting won't break the bank.