I'm creating this thread to track resolution of this issue so others can benefit.

Basically trouble started when I disconnected the battery negative terminal to replace dash trim over the air bag. It manifested first as a transmission fault. Now I see it's an electrical problem and it's going into a shop next week so I will list the findings and resolution here.

Original Thread https://www.jaguarforums.com/forum/s...rchid=14939576

Issue: transmission fault causing rough shifting from park/reverse and trouble shifting at speed sometimes. High beams stopped working sporadically. All lights stopped working sporadically. error message for ebrake. Fault codes for voltage at door module and TCM as well as sporadic electrical codes.

Things tried:
Trickle charge battery
replace battery
check grounds
check battery alternator voltage
hard reset (disconnect, wait, short terminals)

All of these had occasional effects. Sometimes car runs fine. then it will lose it's mind. I don't have ramps or a lift, or time LOL so it's off to a specialty shop to figure it out.

If you have these issues watch this thread for results next week!

 

Somebody may have suggested this before, so apologies if they have.. but have you attended to the ground posts behind each headlamp? Lots of information on this if you search

 

If there are any problems with the wipers it could be the earths behind the headlights

 

Issue Resolved. Issue was rodent damage to some wires and a loose connector as well. Finding a mechanic to work on this as I have no lift or ramps, and no expertise, was a challenge. Jaguar dealer wouldn't touch it, and even the European auto shops wanted nothing to do with it. In the end we had it taken an hour south to Kittery, Maine (USA) for service at a place called Auto Works (Kittery, Maine). They fixed everything and I will return for anything too difficult for me to tackle!

 

Issue came back! We were seeing the car throw codes after leaving it unplugged from our trickle charger. Figured we would take it back to the our repair place that is 45 minutes away. Turns out it was a rainy day, and on the way things really went haywire. Lights and wipers stopped working, TCM codes etc. Pulled over and hooked up the code reader and cleared the codes everything started working again.

We left the car there for them to debug, and they found water in the rear fuse box. They dried it out and checked the ground all over but didn't find any issues and had no more time to instigate going into a holiday weekend. We never take it out in the rain so we can fix the leak later . They had cleared the codes and said everything was running fine. We pick it up and it throws codes a mile down the road. Since it wasn't plugged in I figure its the damn parasitic drain that we really wanted them to find. We drive on a bit to give the alternator a go at adding some charge, clear codes and make it home without further issue.

So now I'm on to fix this parasitic draw myself. I get a pretty good multimeter at the local auto place and hookup to test a draw. 640 mA!!!!!! Lef tit to sit for half an hour it was still 650mA. I decide to start pulling (rather than probing) fuses in the luggage fuse box. Halfway through f47 (I think) the front heated seat fuse pulls and the leakage goes away. So, I've left that fuse out for now and am recharging the battery. hopefully this was it and we can debug that circuit at our leasure while still being able to enjoy the car.

 

I had a similar problem (battery drain) on my RR recently. Putting a clamp meter (just a cheap Chinese one) on the battery negative and pulling fuses in the cabin fuse box found the culprit circuit for me too. It's a bit of a long winded exercise but worked for me.

 

Leaving the car for half an hour may before starting the tests may not be enough time for all electronic module to go into sleep mode, some of them may up to 40-45 min. I would wait a bit longer to be on the safe side.

Best regards,

Thomas

 

That's a very good point. The RR took about 25mins to fall asleep....
I also had to tape the bonnet switch and to latch the passenger door lock to make the car think all openings were closed...

 

Maybe final update on this issue. After leaving the heated seat fuse out and charging up the battery overnight I started it up in the morning and scanned codes. all looked good. A few spins around the block and no issues. Then parked it for about four hours and took it out for a drive lasting 40 minutes. No issues. Then parked it overnight, unplugged. Late the next afternoon took it out for a drive and no issues.

We still have to debug the heated seat circuit (probably the switch) but we don't use the heated seats so it can wait. Being able to leave it unplugged without a TCM/ DDM fault for battery voltage out of range is a big win at this point. Thanks to all the folks here for ideas and how-tos. Im sure there will be other issues, but I wanted to let everyone know that this one is debugged and resolved!

 

Thanks for the feedback, nice to know that you could narrow down the problem!

Best regards,

Thomas

 

The front electronics module drives the heated seats directly.......there is no external driver module for the seats (unlike the steering wheel heater).
You might be able to isolate this further as to whether it is the left or right front seat that is absorbing that leakage current.
Don't know that it would be the switch pack on the centre console as 650mA is a low current providing only about 8 watts of heating to the seat which is not likely to be a valid output (unless the seat elements are faulty and have high resistance and cannot draw a higher current).
My guess would be that you possibly have a power FET in the front electronics module that has gone leaky, delivering some power all the time to the recipient seat regardless of console switch setting.
As long as you know which seat is drawing the current, tracing back to the correct output of the FEM should be easy.
If it is a FET that has failed, then confirming and replacing it (with an original device or equivalent) shouldn't be a show stopper for someone with some moderate electronics skills.

 

Another week and still no need for the trickle charger!