Help! I just got my '93 convertible running again, and now it has a new behavior I have never seen in any car.

I literally just got home, and as I was walking away after locking it up, I noticed that the side lights are blinking (about every 3 seconds). After a walk-around, I see all the side-lamps plus the license plate lights on the trunk lid blinking (although I just now see my right-rear side lamp is out), and can I hear a relay under the hood clicking in time. When I get back in the car, I can see the bulb-out idiot light flashing in time as well. Also, I had previously noticed that when opening the door with the key out, instead of the solid buzzer tone I occasionally get, the buzzer was beeping, and this is also in time with the blinking.

Aside from the right-rear side lamp, the left-front turn signal is also out, but this has been true for some time with no other effects. None of the other lamps are going off, and the car runs and acts normally with the power turned on.

Is this indicative of a short somewhere? I just disconnected the battery as a precaution.

Is my car trying to tell me something?

 

Is my car trying to tell me something?

yeah - it's possessed!!

 

I would initially suspect a weak or failing battery.

But, your symptoms are very familiar.

Before you fully reconnect the battery, connect the _ve and touch the +ve lead to the -ve terminal. (hard reset).

On my 92 XJ40, reconnect the battery; turn ignition to on (do not start the car) open and disconnect the wire from the alarm dome. Turn ignition off, reconnect the wire, remove key.

No real rhyme or reason, sometimes I've had to reconnect the wire with the ignition on, before I get the alarm reset tone, and the blinking/clicking stops. (a fast double, tick-tock, tick-tock).

 

I so thought that this was was going to be a bad battery connection.

I noticed when I took the negative lead off the post that it popped off too easily. I had just picked up the car from the shop after some service on the ignition, and I guessed they'd simply neglected to properly tighten the post clamp.

However, when I tried to reconnect and tighten the clamp myself I found another problem. The nut on the clamp is some weird mutant size; no metric or standard tool would fit this nut--just too large for a 1/2" or 13mm, way too small for anything bigger. So, basically impossible to properly tighten.

One trip to the hardware store later with the clamp bolt in hand, and I return with fresh 1/2" hex nuts. The bolt turned out to be 5/16-18, did somebody replace these battery cables at some point? I expected metric.

After tightening post clamps correctly, the problem still exists. I performed the reset procedure described (thanks very much--I was unaware of this trick). I grounded the positive lead to the negative post on a count of 40, and then reconnected. The problems still exists.

I decided to look at the relay I could hear clicking; my electrical guide does in fact identify this component as the side light relay. That gave me some fresh keywords for googling, and I found an important clue right here. Same year, same problem. I disconnected the security ECU at the block connector, and the problem is gone.

Unfortunately, plugging it back in restores the mad clicking. So are there further steps I can try to solve this problem without a vestigial security ECU?

 

UPDATE: I just tried hard resetting again after reading reset protocols that indicate I need to have the power on at the ignition switch for the ECUs to reset. So following the indicated best practice from throughout these forums...

1. Connected the security ECU and battery normally (blinking occurs).
2. Pulled the negative lead off the battery terminal.
3. Put the key in and turned to position 2.
4. Touch the negative lead to the positive post (held for 30+ seconds).
5. Pulled the ignition key.
6. Reconnected the negative lead to the battery (blinking resumes).

 

Problem solved.

I talked to my shop about the issue, and they asked me to bring the car in. They determined that the battery was part of the problem, and it's been replaced with a high capacity Interstate unit. They were able to clear the ECU by cleaning up the keyless remote and replacing its battery, and then repeatedly operating the locks with both the key and the remote.

 

DEar fellow XJS (and others as well) owners. Be aware that there is a scam artist that has a very sophisticated page that appears when signed on to Jaguar Forums that purports to hook you up on line with a Jaguar mechanic of vast experience for a small fee. They ask for your information including your credit card number which I gave them because I thought it was a Jag forum service and after giving the information the page went dead. Graham says it is a scam so beware of it or you may have to get a new card number like I did or worse. This is the second time in a week I've been scammed; the other one was a false renewal notice for Scientific American Magazine. What is the worl coming to? !!
Jim S (stix66rb)