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anti-lock light stays on

Posted: Mon Nov 06, 2017 10:26 pm
by cedriccools
My anti-lock light is burning when I start the car, it doesn't go out after a while or so, it stays burningn :-)

now, I checked the forum and that could be a sign that the overvoltage relay has a broken fuse inside.

now, for some reason I can't find the overvoltage relay on my car (xj40 4.0 sovereign 1989.

I read it should be in the boot around the fuelfill area, or in the front mounted on the aircon blower.

i checked all the relays in the front, but couldnt get any wiser from it. the only one i thought it could be is this one.

Image


Image


I opened it but can't see a fuse.. is there anyone who has a picutre of the inside/outside from this overvoltage relay?

Re: anti-lock light stays on

Posted: Tue Nov 07, 2017 12:10 pm
by naki_k
The over voltage relay is only on the 3.6/ 2.9 Digital Dash Models.

You need to check all your ABS sensors with a multimeter. Plus do a visual check for any wiring damage.

Do the brakes still work as normal?
Are the brake discs corroded, (from a long time standing).

Also check the plug pins on the ABS ecu, for any damp/ corrosion. (In the boot, behind the Right side carpet).

That relay in the picture is an aftermarket addition. Perhaps for an aftermarket alarm? Or often a bodge for something, rather than a proper fix. Follow where the wires go, to lead you.

Re: anti-lock light stays on

Posted: Tue Nov 07, 2017 12:21 pm
by nlcrane
naki_k wrote:The over voltage relay is only on the 3.6/ 2.9 Digital Dash Models.

You need to check all your ABS sensors with a multimeter. Plus do a visual check for any wiring damage.

Do the brakes still work as normal?
Are the brake discs corroded, (from a long time standing).

Also check the plug pins on the ABS ecu, for any damp/ corrosion. (In the boot, behind the Right side carpet).

That relay in the picture is an aftermarket addition. Perhaps for an aftermarket alarm? Or often a bodge for something, rather than a proper fix. Follow where the wires go, to lead you.


My sentiments exactly, that relay doesn’t look like a Jaguar installation, too recent for that and Jaguar didn’t mount relays without a plug in relay base. According to the schematics, the over voltage relay is mounted in the trunk (boot) on the left side under the trunk trim panel. It contains a relay, a zener diode (overvoltage detection) and a fuse (overvoltage protection). There is also a shrink insulated quench diode, external to the relay, but connected to it (to quench the reverse emf generated by a collapsing magnetic field).

Re: anti-lock light stays on

Posted: Tue Nov 07, 2017 12:33 pm
by nlcrane
This may help a wee bit as well.

viewtopic.php?t=997927#p175733

Re: anti-lock light stays on

Posted: Tue Nov 07, 2017 1:38 pm
by katar83
Isnt there a procedure to test the ABS system on a 40? You basically put a pin in the boot plug, then turn the ignition key to position X and wait and see how many times display flashes. You get the code from this and know straight away whats broken.

I'm pretty certain I did this with mine but that was years ago so I might be making this up, or this might only work with later cars?

Re: anti-lock light stays on

Posted: Wed Jan 03, 2018 8:44 am
by cedriccools
Problem is solved. the left front ABS sensor was completely stuck and broken :-)

Re: anti-lock light stays on

Posted: Wed Jan 03, 2018 8:57 pm
by naki_k
cedriccools wrote:Problem is solved. the left front ABS sensor was completely stuck and broken :-)


There you go. Saves time to check the basics first.
I have a spare if needed.