Recently I started getting a message that my 1998 XK8 had a rear bulb failure. I checked all the bulbs and they are working. The message only appears when in reverse with the brake on, as when preparing to back out of the garage, or when signaling for a left turn with the brake on, as when decelerating prior to the turn. Right turns are ok. Does anyone have any experience with this problem?

Submitted by stevejag@sbcgl… on Mon, 03/26/2012 - 11:43

The additional grounding is always a good idea. What some overlook when checking the bulbs is the electrical connection to the lamp board. Separate the connector and make sure there are not any terminals dark and burned, especially the ground terminal at one end. Sometimes it so severe the connector is beyond repair.
When that happens we have to call our buddy at Coventry West for a salvaged connector; or fabricate our own new ground.

Good luck!

Submitted by joshbartlett@r… on Sun, 03/25/2012 - 16:54

Edited on 2012-03-25 16:56:31

I have had a continuing problem with rear bulb failure warnings on a '97 XK-8. The bulbs were good, and even sometimes worked but I got the warnings. I traced it to faulty grounding of the rear light module - the ground wire/connection was not up to the load and had been arcing, sending a bad signal (open circuit) to the brain.

The fix for this seems to be to add an additional ground source by grounding the whole bulb mounting "plate" to another body connection with a 16 Ga. wire between a body bolt and a soldered connection to the plate. Problem solved!

Submitted by eweber@triad.rr.com on Fri, 01/06/2012 - 14:07

Thanks, Doug & George. It sounds like you both feel the current draw could be causing the fail message. I will check the bulbs further and report back to you.

Submitted by SE98-32482CJ on Tue, 01/03/2012 - 14:38

Eric the Jaguars are very sensitive to using the exact correct bulb. While you can purchase a bulb over the counter at a parts store--and it will work--if it is not made exactly to Jaguar spec it will throw a failure message--while it functions--the failure module is reading a resistance that is out of spec.

Submitted by riscoe@cox.net on Tue, 01/03/2012 - 12:31

Well, if it were me, and maybe some day it will be, I'd start by swapping your tail lamps left to right, one pair at a time, and see if it follows to the right turn signal/brake scenario. If so, then it is just a bulb change. If not, then it gets complicated.
My guess is that the car measures the current draw through the bulb circuits, and anything above or below a predetermined current draw will generate the message. I have run across a rare occasion where a bulb filliment will break, then fall back against its electrical contact, allowing it to illuminate, but the current draw will be different due to the change in filliment resistance.