The idiot light for the ABS (located to the left of the service light) stays on all the time on this 88 740T. The car has been sitting for several years and I am just getting it roadworthy. Can anyone tell me where to start looking, to get it to shut off, short of disconnecting the bulb? The brakes work fine.
Thanks in advance
JD

Check the wiring to the speed sensors on each front wheel, and on the rear axle. Since the car has been sitting for a long time, it would also be a good idea to look at the tone rings on each front hub. If they become rusty, it can cause distort the speed signal and cause the light to come on. It is also common for magnetic debris to build up on the tips of the front wheel sensors, and when there gets to be too much of it, it will spoil the signal and light the light.

Does the light come on when you turn the key on, then go out when you start the engine, then come on again as soon as the car moves, or does it come on with the key and remain on continuously? Normally, the system resets itself each time the key is turned off. I had an 88 740 GLE with ABS, which had various wiring faults over the time I owned it, and sometimes the light would come on while driving, after which it would stay on until I turned the car off, then it would come on again when I turned the car on, go out when it started, and come on again when I hit a bump or something that would cause the bad wire to wiggle and momentarily break the connection.

See the 700/900 FAQ section in the "select shortcut" menu at the top right of the screen for more detailed information on the ABS.

Good morning;
The ABS light comes on with the ignition and remains on all the time while driving.

I am finding a few other strange wiring issues now, such as no dash lights. I had dash lights on Saturday, but none when I took it for a test run the next day. When I checked the fuse for the lights, there was no power either side of the holder.

And a dome light that will only turn halfway off with door closure.

I'm wondering if there is a major connector somewhere that is providing intermitant service.

JD

The way the light is acting, plus the other problems, suggests that your ABS issue is electrical in nature, rather than a sensor or wire. A bad ground is a likely cause. There are ground points under the hood on each side, near the front of the car, and behind each kick panel in the front foot wells. There is also a single black ground wire that comes out of the ABS modulator and goes to one of the mounting bolts. I recommend that you locate each of these and thoroughly clean all the terminals. Spraying with WD40 and unplugging and replugging each connector several times will usually do it. Also loosen the bolt or screw that holds the grounding connector strip to the body shell and work it back and forth to ensure metal to metal contact. You might also want to take the instrument cluster out (it's easy to do) and VERY CAREFULLY clean all the contacts on the circuit foil where the connectors plug on. Polish them gently with a pencil eraser until they are clean shiny copper, then work the connectors back and forth a couple of times when reinstalling.

...I dunno what the deal was with that other guy, but anyway....

Yeah. I would start out with the fuses. An 88 won't have an OBD setup for the ABS so don't bother looking.

There are some relays under the driver's side kick panel, and you can check the wheel sensors as well. I don't know if the light is a permanent on after x amount of time or not, but it may be.

You could pull the battery cable (black/neg/ground) for 10 minutes and see what happens afterwards.

Good luck and post what you find,
Will
--
1990 740 Turbo, on its way to stock specs, maybe beyond

Maybe the light is informing you that the ABS module or some part of the system is faulty. You better not ignore it, this is part of the safety design of this car.