W126 ABS light - return of

[Rod Adams]

Afternoon all,

A while ago I posted re the ABS light coming on intermitently on my 1990 W126 420 se. General consensus was to replace the brake light switch. I bought one at the time and have just got round to fitting it.

What I expect to find was a switch with two connectors, as per the purchased one. What I found was a switch with one connector. The switch was the same layout and mode of operation, so I fitted it anyway as I was in there. I haven't had it out fopr a road test yet, so not sure if the intermitten fault is gone or not.

Also attached to the brake pedal was a cable arrangement which is pulled when the pedal is pressed This cable disappears into the centre console somewhere. Is this an alternative to the brake light switch with two connectors? If so, is there a switch in the other end of the cabel which is likely to have failed? and is causing the problem? If so, where is it?

Cheers,

Rod.

 

[Flash]

Couple of members on here Ian B Walker and MBTechnician I'm sure would be able to tell you as they are in this line of work...

 

[Ian B Walker]

Two other things will cause the ABS light to come on. A half charged battery or a dickie OVP relay. A half charged battery will allow you to start the car and drive as you would. But a full charge for some reason turns the light off. I have also come across cases of faulty OVP relays doing all sorts of wierd things. Check the fuse on top and the soldered connections inside it. As for the switch, not sure about this. Will have a think and get back to you.

 

[LastMinute]

Also attached to the brake pedal was a cable arrangement which is pulled when the pedal is pressed

Is that the gear lever interlock cable? (The mechanism that stops you shifting out of park without the brake pedal being pressed.)

 

[Rod Adams]

Thanks for the replies.
The cable coule well be the interlock with the gearbox, it heads off in that direction anyway. I think the battery is OK, it starts no problem even after a few days sitting and frosty nights and it tends to happen after a couple of miles running, usually at a roundabout after braking, but not whilst braking. I'll check out the OVP relay as suggested.

Any other suggestions welcome!

Cheers,
Rod.

 

[Rod Adams]

I think I've fixed it! I took out the sensors on the front hubs and they were covered in black gunge. Cleaned them up and put them back, did the same with the one in the diff. and hey presto, no light. So far anyway! It was an intermittent fault but previously it happened virtually every trip within a couple of miles. I've now done 20 miles and no light, so fingers crossed!

Cheers,

Rod.

 

[Howard]

:bannana: