2003 XK8 4.2 coupé.
Got the boot (trunk) repainted, nice paint job, but the key fobs stopped working properly.
Previous situation - both fobs worked fine, from 15m
New situation - both fobs work fine, from 1m, i.e. you have to put your hand on the rear window glass where the antenna is for both to work.

Put new battery in each fob, made no difference.
Thought antenna was disconnected, but it is connected ok, by wire in the roof.
Reprogrammed the fobs several times with the procedure and this is where things get weird.
At first, doing this made no difference, i.e. both fobs worked from short distance.
Cleaned the contacts with rubbing alcohol, but they weren't that dirty.
Now the second fob will open the boot (trunk) when I walk to the car, without me pressing the button. Did this 3 times just to make sure. Now I thought this was odd, this model doesn't have keyless entry... The second fob is continuously sending a signal to the car, the alcohol caused a short circuit?

Any ideas? About the sudden very short range for both fobs?
Thanks.
Simon
2003 XK8 coupé

 

Welcome to the forum Simon,

(I've deleted your duplicate post of this question in X-Type forum.)

Was anything dismantled to repaint the boot or was it masked and done in-situ? If the latter, then there should be no connection with the behaviour of the locking and security system. If there was dismantling, you need to check the condition of the boot harness and connections.

Fob programming is a separate issue from fob range. The fob is either successfully linked with the vehicle or linking fails.

Range is normally a function of fob battery condition and they do tend to fail quickly rather than a gradual reduction in performance. The boot opening as you approach the vehicle certainly suggests the unlock button is shorted. Sending a continuous signal like this will also rapidly effect the life of the new battery.

When you get a minute, please follow this link New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum to the New Member Area - Intro a MUST forum and post some information about yourself and your vehicle for all members to see. In return you'll get a proper welcome and some useful advice about posting to the forum.

Graham

 

Thanks Graham. I'll describe one problem at a time.

I think I permanently damaged the second fob by cleaning the contacts with alcohol. I guess I caused a short and blew the chip when the fob battery was reconnected and the alcohol caused a short circuit. Drying it in the sun now, but I don't expect it'll make a difference.

The real problem is the 1m range of the first (good) fob. The body shop did remove the chrome/boot switch part when re-spraying, to get a better result. I'm checking all the boot harness wirings now and everything seems ok. The coax cable (from the rear window antenna, via the roof lining) runs into the 433kHz module under the boot fuse box, looks ok. Checking the wiring from the antenna to that box now. There are a couple of unconnected plugs, but I can't see where they'd go. I think they are there for compatibility, e.g. with the cabrio, and are not used in the coupé.

The boot re-spray was the last job to make the XK8 "perfect", so not there yet until I solve this

 

Simon,

The antenna cable/connection sounds a likely culprit.

Unconnected harness plugs are not uncommon on Jaguars. They come pre-wired for most of the options so there will be unused ones.

Fobs regularly turn up on ebay. If you get a replacement that way, be sure it's European 433 kHz frequency and matches the code on the back of your existing fobs.

Graham

 

Thanks for your reply.

The electrical connection between antenna and SLM was good, extended the cable length on the multi-meter to check.
I'll be in York in August if you know where I could source a SLM not too expensive...