'85 280SL no OVP fitted?

[woolf]

I can't find an OVP relay in my car, and my dealer says that my chassis doesn't have one listed for it anyway, so I guess I don't have one.

So does that mean my ABS has no protection from over-voltage

If so that may explain why the ABS warning light is always on, and that I probably have a cooked ABS ECU.

Any comments/confirmations gratefully received

[david s poole]

have you removed the cover around the fuse box?[necessary to remove lower panel under glove box first]above the fuses,on the door hinge side you will find the ovp with red top and 10amp fuse in it.

[woolf]

Thanks David, and yes I've had the kick-panel out and identified every relay in there, and there's definately nothing with a fuse.
The only relays I couldn't identify were 4 identical small silver cans, that I swapped around just to see if it made any difference. It didn't

I've also renewed every fuse in the fuse box, in case one was related, but still no change to the ABS light.

I've even had my dealer check the ABS and they couldn't find any faults in the sensors, but didn't have old enough equipment to check the ECU or pump.

[Gilly]

If it has it, would be behind the glovebox, there is what I would call a "shelf" behind there and would be on that.
Gilly

[woolf]

Originally Posted by Gilly

If it has it, would be behind the glovebox, there is what I would call a "shelf" behind there and would be on that.
Gilly

Incredible - you are spot on! Many thanks for that, you've put an end to two weeks of hunting.

Funny how the main dealers never know this kind of thing.

The fuse was ok, but the relay does rattle when shaken, which I'm sure is a bad sign. Although it does check out ok with a multimeter and 12v applied to it. Still, it's a cheaper thing to try replacing first than the ECU.

I owe you a beer (or ten).

[Gilly]

For some reason what David was saying rang a bell too, but I DO remember having found one up on that shelf, I thought the fuel pump relay was up there too....
Gilly

[Gilly]

woolf: The brown wire is a ground, power is red and comes from the battery according to my diagram, so yeah maybe tap into power whereever you can, I assume battery is in the trunk. But check the RED wire for power. If I am reading the diagram right (poor quality MB discs) it is socket #1. Socket #2 is an output to the engine computer and is also going to the ABS. That one is a 2 wire, a black wire and a red with blue stripe. #8 is a black with red stripe, comes from fuse 7. Looks like ground is socket 5? Only 4 sockets used on that connector. This all assumes it's the same as a 85 380SL (US)
Gilly

[woolf]

Originally Posted by Gilly

woolf: The brown wire is a ground, power is red and comes from the battery according to my diagram, so yeah maybe tap into power whereever you can, I assume battery is in the trunk. But check the RED wire for power. If I am reading the diagram right (poor quality MB discs) it is socket #1. Socket #2 is an output to the engine computer and is also going to the ABS. That one is a 2 wire, a black wire and a red with blue stripe. #8 is a black with red stripe, comes from fuse 7. Looks like ground is socket 5? Only 4 sockets used on that connector. This all assumes it's the same as a 85 380SL (US)
Gilly

Thanks again Gilly, mine definately has a different colour scheme it seems.
As a test I cross-wired the ignition signal wire as the power source, so that the relay still had to do it's job, and the ABS worked fine.

I won't keep it like that though, it's probably too much current for the ignition switch circuit.

My battery is only just the other side of the firewall from the OVP, so I may just run a fused wire straight to it.

Thanks again for all your help

[woolf]

I thought I'd post the solution to my problem, in case anyone else ever has the same "fault".

I had decided to run a separate fused supply to the OVP relay, as it wasn't getting it's proper permanent supply, and I couldn't find it's fuse or source.

So I removed the battery to ease feeding the wire through the bulkhead, and trapped underneath the battery was a wire A wire with a ring terminal that looked like it should be attached to the battery post A wire that turned out to be the ABS power source

Evidently whoever changed the battery last failed to reconnect the ABS wire, and subsequently the owner had removed the warning bulb to get it through an MoT.
My local dealer had failed to spot it too, hardly surprising though. At least they had the decency to only charge me for 30 minutes work despite spending 90 minutes on it.

On the positive side, I learned quite a lot about my SL

[rchase]

Originally Posted by woolf

I thought I'd post the solution to my problem, in case anyone else ever has the same "fault".

I had decided to run a separate fused supply to the OVP relay, as it wasn't getting it's proper permanent supply, and I couldn't find it's fuse or source.

So I removed the battery to ease feeding the wire through the bulkhead, and trapped underneath the battery was a wire A wire with a ring terminal that looked like it should be attached to the battery post A wire that turned out to be the ABS power source

Evidently whoever changed the battery last failed to reconnect the ABS wire, and subsequently the owner had removed the warning bulb to get it through an MoT.
My local dealer had failed to spot it too, hardly surprising though. At least they had the decency to only charge me for 30 minutes work despite spending 90 minutes on it.

On the positive side, I learned quite a lot about my SL

I think you should laugh. Your car is fixed and you have the satisfaction of being able to do what the Mercedes dealer could not.