I disconnected it from the trunk floor and negative terminal and tossed it in a spare parts box. It's the right size for my lawn tractor battery when the cable corrodes away.

pat

 

Just wanted to update this with a final solution. Well, about 10 days after I declared All was well in post #14 above, all the error messages came back. I didn't want to continue to post here until I found out the problem. One of the error messages indicated RR wheel sensor as the fault. I replaced the wheel sensor and everything worked for a few days then the problem would return. I'd clear the codes and I'd be good for some random amount of time and the dash would light up with all the same error messages. I checked every ground connection under the car, wheel well, etc and everything was good.

Finally, I gave up and against my better judgement took it to the Jag dealer. They kept the car for 2 weeks, told me it was a short somewhere. After realizing they weren't interested in solving the problem (their communication was awful) I retrieved my car; they charged me for 1 hours labor-tells you how much they worked on it in two weeks.

I spent the winter doing various tests etc. and I would always get the errors back, sometimes immediately sometimes 100 miles later.

Upon a recommendation, I took my car to Motorcars Inc in Plainville, CT. They found that if they monitor the output of the wheel speed sensors (L and R) while on a lift with the car running the right sensor would occasionally yield erratic results. Tracing backwards there was a loose female connection where the sensor connects to a larger harness under the car. ( I can take a pic the next time I've got it on the lift if anyone is interested). They tightened the connector, plugged it back together and secured it. Problem solved.

In retrospect, many of the instances when the errors would occur would be after relatively hard braking or hitting small bumps or potholes-all consistent with a loose connection.

Can't say enough positive things about Motorcars Inc. They did some fantastic sleuthing. They also have a stash of lovely E-types on site.

 

Great troubleshooting there, not easy to discern, I am sure!

 

Dealers are generally not good at diagnosing tricky issues - they'd rather just swap modules at the owner's expense until either the fault, or the customer, goes away.

 

Great that you finally solved the mystery and thanks for doubling back with the solution. I learned a lot from your posts.

 

Thanks Pupilbone. My case seems to be uncommon to what most experience when they find these errors, which is 1) low battery and 2) bad wheel speed sensor based on my readings of this forum. I think the location of the harness connector is not an ideal Jag design and I could foresee others having this issue, though I've not run across it yet. Hopefully, this one data point helps the next person not get so frustrated with the car as I did. Lots of cursing involved.

Cheers.

 

I think it's pretty impressive that we don't see more failures like this, if you look at just how many connectors and harnesses are in these cars. It's great that you found someone who was able to figure it out. We have a member here from GA (who hasn't posted in a few years), whose Firesand vert was diagnosed with a bad wiring harness. As it was under warranty, Jag built a new harness for the car (which took months apparently), and I believe that finally fixed the issue she was having. (Can you imagine how much of the car must have been disassembled?)
https://www.dropbox.com/s/0gff5jjwoq...rence.pdf?dl=0

 

Believe me, I've been over those wiring diagrams trying to trace my issues. My last in-depth auto wiring experience was when I restored an MGB and did a bunch of work on a 1980 911. The Jag is a nightmare in comparison. The adage that a good auto mechanic is nearly as important as a good doctor is spot on. My wife would have had me committed otherwise. .

 

As, I suspect, would be any modern car!