.I have a 2005 s-type when I turn on the right turnsignal the rear bulb and both reverse lights flash real dim and slow??? I have checked all fuses and they are all ok but when i touch a test light to the F48 fuse it flashes on one side of the fuse only when switch is turned to the right. It lights but does not flash when switch is on the left turn. i have obtained new bulbs although the originals were all good. I read elsewhere in the forums that a module could be the culprit but wouldn't the module affect the left side as well? this car has not been altered or cut up and i am very confused due to this system not using conventional grounding. any help would be appreciated. Thanks.

 

You may find these threads of interest:

https://www.jaguarforums.com/forum/s...ystery-219022/


https://www.jaguarforums.com/forum/s...llights-53056/


In both cases, erratic behavior in one circuit was caused by a blown fuse in a different circuit.

 

Thank You!!!!
I wouldn't have believed it had I not seen it myself. there was a partially? blown fuse. Checked out good with a test light but visually, you could see the problem.
Thanks again!

 

Thanks for the update. Glad you found the problem.

I suspect this mystery fuse was 100% open. If there are any dual-filament bulbs in the circuit, they can backfeed voltage to other circuits when the ground is not active.

Basically, when your test light picked up power on both sides of the open fuse, the "downstream" side was probably being backfed through a different circuit. It can all get very confusing.