Strange electric problem.

[JohnPal]

1992 Jaguar Vandenplas (XJ6)

This morning whilst driving on my way to work the radio suddenly went out, and the fuse failure indicator came on. Pressing the VCM button on the dashboard, the "Fuse 1" error code was displayed. "Fine!" says I, "a blown fuse".

Checking the fuse circuit number 1, which is on the passenger side, I was surprised to discover that the 10-amp, number 3 fuse labeled "radio" was in perfect condition. In fact, I tested all the fuses in that fuse box, and they are all fine.

Now, here is the bizarre behaviour; The radio works fine with the ignition in accessory mode, but if I turn any of the interior lights, (dome light) it looses power. Opening the boot, the bonet, anything that draws power, causes the radio to turn off.

If I turn the ignition on (with or without the engine running) the radio dies and the fuse failure comes back on.

Any ideas? Could it be a bad relay?

Thanks in advance.
John.

 

[equiprx]

John,
I had a few cars come in the shop with bad wiring in the headliner for the visor lights. Good luck.

 

[jessebogan]

Hey Ex, did you get anywhere on the XJS w/ wiring issues? ( sorry for the hijack....)

 

[LarryK]

Since it seems to have a problem thru the ignition. Have you looked under the steering/wheel housing and dash to check for a loose ground. Pull radio and check the ground there too. If you have a 3' line to use as a tester, hook it to the back of the radio and a metal ground in dash and retest, do the same under steering wheel/column housing and do the same. Usually when something else is turned on and something looses power is a ground problem or crossed hot wire. Check grounds first. AutoZone, O'Riellys, Advanced Auto etc., sells a short circuit tester pretty cheap which can be used for the crossed wire check.

 

[Exotexs]

Hey Ex, did you get anywhere on the XJS w/ wiring issues? ( sorry for the hijack....)

moi?
Jess, go easy on the high-octane eggnog, it's not even Christmas yet )

The XJS was not my thread.

Ex

 

[jessebogan]

Oooops. That is what I get for trying to think when I am preoccupied.

 

[JohnPal]

Hmmm... Now that I recall, the problem started when I attempted to lower the driver's side sunvisor in order to mitigate the low, early morning sun.

Both the driver's and passenger's sunvisors have a small mirror with a light at each side. The mirror is covered, and the lights turn on when the cover is lifted.

If this should be the cause, any tips on how to fix it?

Thank you.

 

[jessebogan]

Has the headliner been replaced recently? Or have you had the visors off? I have seen screws put through the sunvisor harnesses cause all sorts of bizzare problems. Just for grins, check that all the connectors on the back of the fuse box are clean and tight. I see the occasional weird problems caused by loose connector blocks, or corroded pins at the back of the fuse boxes. You can take off the whole kick panel for access.

 

[equiprx]

Jesse,
Thanks for asking. I installed four 'super grounds' as suggested by Jaguar Bulletin but no joy. Have to leave it alone for a while. Got a bad case of the flu and don't do much of anything right now. Next time I get on a lift I need to check for exhaust leaks since the pipes look misaligned since the trans was rebuilt and vacuum leaks.
Steve

 

[JohnPal]

Halloween update; My Jaguar continues to be haunted. I removed the two sun visors and checked the cabling. They show no signs of damage and power is present (approximately 12 volts). I also removed the radio and reseated the fuse box (passenger's side) connections. However, the problem persists.

I've also noted these additional bizarre behaviours; with the ignition on, if I open the glove box door, the radio works. But, the radio looses power when I close the glove box door or turn on the headlights. Also, with the ignition completely off and the keys out, the AC fan turns on after about 20 seconds if the fan switch is left in low, high, etc.

I will continue to document this problem and the eventual solution in hopes that it will help someone down the road (pun intended).

Cheers... and Happy Halloween!

 

[DrEntropy]

These arbitrary on-off things are usually due to a bad ground someplace.

 

[JohnPal]

Problem fixed. Loose connector in passenger side fuse box.