Hi All,

I've recently had some key fob problems. I took the fob apart and cleaned all the contacts and replaced the battery. It worked well for a little while until...it decided it wouldn't unlock anymore.

After reprogramming (which worked as per notes in other posts) I had the same behaviour and started to suspect my fob may be faulty....except for the fact the reprogramming seemed to work.

What I've also noticed:

• If click the unlock button the car always locks and never unlocks.
• The lock button will randomly will lock the car.
• Sitting inside the car, I can hear faint click sound each time I click lock/unlock on the fob - so it would appear that the fob is actually working. The faint click sound seems to be coming from under NS passenger seat (RH drive model). The security module is on the OS in the boot behind the battery, so I don't think this is where the click is coming from.

Any suggestions welcome...before I take it to the jag dealer for what, no doubt, will be an expensive visit.

Troy.

 

To me it sounds like the fob is pretty much done. Is that the only fob you have? If not, how does the other one function? If that's the only one you have, I'd take it apart again, leave the front outside cover off and press directly on the micro button itself and see if works better for you. I know you said you installed a new battery but, do you have a volt meter to read the actual battery output?

 

First off....check your vehicle's main battery voltage.
As for the fob...the little pads tend to wear out and loose their
contact effectiveness.
Two ways you rectify this is by using a very soft carbon pencil
and give the under sides of the contact pads a good rub depositing
carbon black or, you can cut or punch out some little silver paper
dots to fit in the pad housings....both methods restore a positive
contact situation.
Did this to both my fobs and they work perfectly ;o))

 

Thanks @Addicted2boost and @xjay8

...however, if I'm in the car and press any of the fob buttons I can hear a faint click coming from [what appears to be] under the the rear seat (opposite side to the battery/security module).

...which makes me think that the fob is functioning if the car makes a sound each time I press a button? Is that a fair assumption?

 

Okay, so...just an update for anyone interested :-)

The remote was in fact the problem.

There are two type of these remotes. One relies on the rubber buttons containing conductive compound to complete a circuit when pressed. This type has no "switch" on the actual circuit board.

The second type has actual switches on the board itself. This was my type. Although I had cleaned the entire key fob/circuit board and replaced the battery - what I had missed was that two of the switches were dirty (corrosion/gunk from 15 years of use). This caused one of the tiny switches (lock) to stay depressed/on and the other (unlock) to be erratic.

After a delicate cleaning operation I cleaned them and now the remote is working as good as new.

Please note that you need a very steady hand and delicate working equipment to do this.

Pictures say a 1000 words...




XJR 2001 key fob showing how the buttons can be cleaned.





See how the switch case has tiny feet that hook into the circuit board (and can be easily damaged).