ABS light comes on as i pull away and stays on until i switch of. How can i find thie cause? The car is a 1995 3.2 XJ6 x300.

Can any one help?

 

The simplest way is to hook it up to a diagnostics reader and this will tell you which, if any, wheel speed sensor is suspect, or if it's the ABS module itself.

Dodgy sensors are common enough and often a simple clean up will rectify the problem. Each wheel has a sensor, mounted on the top of the wheel hub and secured with one screw. You'll see the wire running from it. Remove the sensor, which can be quite sticky as they can seize in place somewhat. A little penetrating oil allowed to soak beforehand won't go amiss.

Clean the sensor itself, especially at the base end which sits inside the hub. This is the part that gets the signal from the reluctor ring inside the hub. This is a toothed wheel and can be seen if you look down into the hole that the sensor sits in.

Using a long thin screwdriver, you can also clean the ring, which if memory serves me right, can also be accessed from the inner side of the hub. Rotate the wheel and clean each tooth/gap in turn. These can crud up, also interrupting the signal.

Finally, the ABS module, mounted in the engine bay on the passenger side (RHD) right by the windscreen, can go iffy, with dry soldered joints being the main culprit. Awkward to remove without disconnecting brake lines, but it can be done, as I have had cause to go there! I have some pics around if needed, but maybe concentrate on the sensors first.

If you have cruise control and it works, then your ABS is working also, and so you know you are probably just getting a dodgy signal from a sensor and the module itself is ok. Others will chime in.

Hope this helps.

 

My '95 ABS codes could not be read, even with Autoenginuity. I checked the sensors and connectors and found no problem, finally pulled the module and resoldered the pump wire pins. That was it. This is a common problem with the XK8 & XJ8, apparently also the X300.

 

Thank you both. Ill be looking at the problem this weekend and let you know what I find.

 

Just another thing to try; mine was intermittantly showing the ABS light & someone suggested reseating the plug into the ABS unit - was a nice quick fix!

 

What do you mean to "re-seat" the plug? Which plug?

 

I don't remember there being more than one, but it's a while since I looked! It's a big connector with a screw (/bolt?) holding it in. Just removing & replacing it must have cleaned the contacts enough in my case.

 

Mine started this when I had the car repainted. It wasn't on before they did the prep and paint but it is now. It's off when the engine is started so I assume that the computer is self checking it okay at start up. At about 10 MPH the light comes on and stays until the car is turned off. What could they have messed up?

Finally, on a LHD car where is the controller and what does it look like?

 

They may have done nothing, just coincidence, or they may have somehow damaged one of the cables leading from the sensors. Your symptoms are typical for a dirty sensor or a bad solder connection to the abs pump. The module is at the right rear of the engine compartment, obvious because of the brake lines.

 

They (very) probably didn't do anything to cause this. ABS faults are common with this model.

The ABS system does a self-test at about 10 mph.



On the RH inner fenderwell, near the firewall. Look for lots of metal brake pipes....that's the ABS hydraulic unit. The controller/module is on the underneath side of the hydraulic unit. As mentioned, it's a big connector....probably 20 wires....with a bolt in the middle. Unscrew the bolt, wriggle the connector off, then wriggle it back on and tighten the bolt.

This procedure often restores good contact to any pins that have a tiny amount of dirt on them. Or, just as likely, the wriggling restores contact to weak solder joints on the circuit board inside the controller.

Worth a try.

Cheers
DD

 

Do not disconnect anything without removing the neg. battery cable first. The electronic modules can be damaged.

 

So small update...I did remove the connector, blew it out and stuck it back on the module but it didn't change anything.

I was driving 2 days ago...hit a pothole and the abs light went out! Now...it will just randomly go out and the ABS works. So...now how do I find out where the fault is and fix it? Is there any way to check the sensor on each wheel to see if it is faulty? I have seen some posts for guys that cut open the module and fix the solder points...I'm worried about taking a Dremel to it.

 

If a knock "sorted" your problem and you now find it intermittent, I'd suggest that your module itself is at fault, ie; bad soldered joints. I think the wheel speed sensors can be checked, using a voltmeter, to find the correct impedance/resistance, but I might be corrected on that. A search will throw up any details.

Something to bear in mind is that on my 97 donor, the wheel speed sensors are different to my 96 driver and not interchangeable, just in case you ever pick up some from a breaker. Check compatibility first.

Doing the solder job on the module and taking the unit apart is the easiest part. Getting it out can be a bit awkward. I have just recently posted pics on here of how I tackled this, without removing brake lines.

 

As I understand it the module has to be cut open with a dremel. Is there a write up on that so I know where to cut etc? I just don't want to damage the board or other components in there and end up having to replace it.

I've found a couple images that show the inside, but not where they cut...sometimes it's hard to tell with pictures.

 

When I opened mine, I placed it in a bench vice, wrapped in some soft cloth. Tightened it up just enough to hold it snug. I placed it on "edge" so the top and bottom of the module were sat against each of the vice jaws. I used a junior (small) hacksaw, cutting along the bottom of the lip, formed where the top of the module would have been pressed on originally during manufacture.

I kept the saw very level/horizontal, so that it cut through evenly. I turned the module around, cutting each side in turn. The blade never got too near to anything inside, as there is a bit of clearance inside.

Attached pics may help to clarify.

 

I'd remove, clean and replace the wheel speed sensors and make sure the hold down screw is securely in place.

If anyone of the sensors is misbehaving the ABS light will come on.

 

The light on my 95 was intermittent for a while, then began coming on after 100' of travel. It was the solder connection to the abs pump, and I repaired it just like the XK8:

Cut a hole of 3/4 to 1" dia with a hole saw, no center drill, directly opposite the abs plug. Solder the pins, use JB Weld to close the hole with the cut out piece.

 

You are a freaking genius dude. Valuable info.

So I just "reball" the solder right? Don't add any solder to it. Just hear it up enough to fix any cracks or breaks in the material?

 

You will have to scrape the coating off the pins. When I did mine, just heating the solder was not good enough, so I used a touch of paste flux and some silver solder, then cleaned with wet q tip and coated the pins with epoxy.

 

I don't know what paste flux is. Did you add solder to the existing or completely de- solder and add new solder? I've not had great luck with soldering fixes in the past ( headphones mostly). If I mess it up, it's a couple bucks. If I mess this up, it's hundreds$$$???

What exactly did you clean with a wet q-tip?