After I thought the big issues are finally sorted, my green gremlin is now eating the battery away faster than ever.
After searching a lot through this forum and another it looks like there is a good chance that I have this Rear-Electronic-Module-waking-up problem.
I connected an amp-meter and set the digital camera to automatic 1 picture per minute in the trunk to record the behavior over longer time. By that I found that the electronics, after gradually falling asleep as they should within about 45 minutes, sometimes seem to go insomniac at random times and wake up to around 2 A consumption in the middle of the night, followed by another roughly 45 minute until the last gremlin has fallen asleep again.

This looks very much like the described behavior that REM and/or FEM of earlier models cause such drain.

So I went out to hunt down a new REM (which is just easier to change than the FEM and seems to be responsible more often). Changed today, car doesn't run with it. It starts hesitantly, engine runs for about 6s, then it dies again. Changed back to the old one and all runs as should.

My original REM was a 2W9F-13B524-AF. The replacement I found is a 2W9F-13B524-AH, so in the OEM logic should be 2 modifications newer. I had hoped the fault had been eliminated by then. All other relevant part numbers on the 2 REM are identical
Now my actual question:
a) does anyone know if the different REM change levels are exchangeable? So should the -AH in general work on a car originally equipped with an -AF?
b) does this module need to be somehow programmed to be accepted by the rest of the electronic gremlins in the car?

All ran so perfectly, now that all 32 valve clearances are back to where they belong, the transmission is changed, PCV is ok and all sensors showing up in the DTC codes are fixed, just to get into the next issue.
Who has fixed such a battery drain problem on an X350 already and cares to share the experience?

Cheers,
Jochen

P.S.: It's not the battery, that's checked.

 

Maybe worth trying this one?



https://www.autoreservejaguar.com/ja...13b524-af.html

 

I'm pretty sure the REM has to be programmed to the car.
So if you change it you will need a session on the jag software to program the new module
I think from memory the REM has 'this unit is programmable' or something to that effect on the label

 

meirion1, looks like I might need an AF, but I still hope the successor can also be programmed to work in my car

paddyx350, you are right, I got info that you need to read out the data from the old one first and then transfer the config back to the new one after the replacement. Wonder what to do when the old one really is fried.

today one relais in the rear fuse box went mad and didn't stop clicking. Unfortunately one of the non-servicable ones on the lower deck. Does any expert here know what the marked Relais in the rear fuse box is switching?

 

You should be able to work it out from the electrical guide.

There are four there- the bottom two are R7 and R8

Rear fuse box

 

I'll have to check the plans on a bigger screen again. Up to now I only found the numbers and remark they are not serviceable.
Didn't find these non-servicabel relais in the detail electric diagrams yet.

Can't this car once break something that can be just pulled and plugged back for a change?

 

The whole fuse box can be unplugged and replaced if necessary.

Used ones are available and not expensive.

 

Thanks meirion1, I saw they can be ebayed for around 60..80 pounds.
Just worried that an old used one may be in a similar state of decay and will die on me again.
And the actuation of the relais in question is by the REM, so that would be my first target to fix when I'm out of the current business-trip mania and see hme again for some days.
Hopefully the usually totally useless Jaguar dealer close by can at least download and transfer back the config data from a changed REM ... last time I was there they were not even able to connect their computer to the car.

 

From what I have read on this forum Main dealers can be incompetent or crooked or both and always expensive.

 

Tried a used -AH and -AF by now, both show the same behavior. Difficult to start the engine, when started it dies again after a few seconds. Typical sign of the anti-theft system kicking in.
According to the official Jaguar Classic representative the REM can theoretically be programmed, but in reality it usually fails to give them a new identity and a new VIN. I'll try nevertheless when I have time to take the car the 160km there. At least I finally found people who still intimately know these cars.

Has anyone here ever successfully swapped an REM or FEM on an X350 with a used part? I read positive reports on S-Type REM, but didn't find first hand experiences for an XJ8. Will report back after trying.