In trying to diagnose my non-working speedo on my 1994 XJ6 I jacked up the rear of the car this evening and took a look at the ABS sensors on both rear wheels.
Since I did not see anything unusual, I traced the wires back to connectors inside the trunk. I pulled the connectors apart and checked them with an OHM meter.
I tried it with a 2K setting on the OHM meter and a 20K setting and both gave infinite resistance or totally open circuits in each one.
I am assuming this is "bad"
Is there a way to rewire these or otherwise repair them since as I understand XJ40 rear wheel ABS sensors are nearly unobtainable.

Any information would be most helpful.

 

Hi Steve,

Off the top of my head, I believe the ABS sensors should measure a DC resistance of between 1,200 ohms (1.2 kohms) and 2,000 ohms (2.0 kohms), but I may be thinking of the later saloons (X300/X308). Did you try measuring at a higher range on your meter (100K, 1M)?

Another test you can try while your meter is connected is to manipulate the wiring harness to each sensor to see if you can discover a break in the wire. Flex the wire every inch along its length and see if the resistance jumps from infinity to something less. If it does, you have found the break.

Cheers,
Don

 

I came across a post from Alex Koch in August of 2015 on the Jag-Lovers forums where he talks about being able to use an ABS wheel sensor from a Renault Twingo that he was able to source quite cheaply from the UK Ebay site.
He provided some directions about some mods required to accomplish the switch over on his XJ40 and said as soon as he completed the job his speedo started working 100% correctly with no more gliches.

Has anyone else here heard of this or tried it?

 

I also found another write-up where an ABS wheel sensor from an Audi A4 is suggested.
Again any direct experience with using these as a replacement on the XJ40 would be most appreciated.

 

I read some threads on this a few years ago and as I remember it was the length that differed (replacement was longer) and the OP used washers or a spacer to match up with the air gap on the XJ40,.plus I think the harness had to be spliced.

Made sense. As long as the diameters are the same and the length can be matched up, no reason why another brand wouldn't be just fine.

Larry

 

Hi Steve,

I haven't tried either a Renault or Audi ABS wheel speed sensor in an XJ40, but if I recall correctly, Alex Koch is the chap who discovered that the Renault Megane Idle Air Control Valve works in the later XJ40s, and I have confirmed that for myself, so I'd say it's worth trying Alex's recommendation on this as well, if you can find the Twingo sensors cheap.

I would think that just about any inductive ABS sensor with an appropriate length and barrel diameter might be made to work. Obviously, the later Hall Effect sensors would not work.

Cheers,

Don