Ok folks..I have a 2000 s-type when I turn on the right turn signal the rear bulb and both reverse lights flash real dim and slow??? I also noticed while looking around back there that someone has run a jumper from the right tail light to the left. Unhooked that and it didn't change anything other than the right brake light going out ...so I put it back lol...any suggestions? Thanks

 

Wiring diagrams for your car are here:

JagRepair.com - Jaguar Repair Information Resource

Open the PDF for your year and scroll down to Section 8.2.

Unless you have damaged wiring, the most likely culprit is the Rear Electronic Control Module.

Please note the control of the exterior lighting is different than on most vehicles. Jag uses a constant power supply to the bulbs, and the control module switches them on and off through individual grounds. The taillight assembly is completely insulated from the chassis.

On most other vehicles, the bulbs all have constant grounds to the chassis, and power supply is switched on and off. With that system, the loss of a common ground (between the taillight assembly and chassis) can cause all sorts of strange behavior, with other bulbs lighting up at half brightness, etc.

If you had your same symptoms on a non-Jag system, I'd almost certainly say you lost a common ground somewhere, but that's not going to be the case for any of our Jags. Unfortunately, I think that Rear Electronic Control Module is at fault.

 

Thanks I'll check into that and let you know.

 

Had the same problem and it was a blown fuse. Pull the fuses and check them first.

 

Good suggestion. I got to thinking it may also be worthwhile to check all of the bulbs for correct part numbers. A wrong bulb(s) could throw things off. Are you getting any lighting failure messages on the instrument cluster?

 

Right tail light failure

 

Ah, now we're getting somewhere. Try swapping that bulb with the left side and see if the message follows.

 

I'll try that..

 

Nothing changed...there is a wire ran from the left bulb housing over to the right wires..when unhooked the right side doesn't work...

 

We are moving into headscratching territory now. Do you have the trunk liner removed for access? I'd suggest giving the wiring harness a good visual inspection for any chaffed spots, etc.

After that, I'd probably unhook the connectors from the RECM. The wiring diagram linked above shows details of the connectors on page 29. You'll be looking at connectors CA63 and CA100.

Using the diagram on figure 8.2, ground the relevant pins on the harness (not the module) one by one to turn on the corresponding circuit. If the correct bulb lights up (and only that bulb), that indicates you've got a good power supply and wiring in that circuit has continuity. (We'll test for other faults in a minute)

If more than one circuit lights up at a time, this would indicate wires rubbing together somewhere or a bad bulb. Sometimes the filament breaks inside a dual-filament bulb in such a way as to bridge over to the other circuit inside the bulb. This can be a troubleshooting nightmare, as two normally independent circuits are now connected.. So if you get more than one circuit lighting up at a time, go back and remove all the bulbs on BOTH taillight assemblies and start from scratch with new bulbs.

Please note the "tail" circuit has two bulbs in parallel on each side, so they should both illuminate when their circuit is energized. The stop, turn, fog, and reverse circuits only have one bulb per side.

The other thing to check is for wires rubbing together somewhere in the harness. Remove all bulbs from both sides, and check for continuity between all wires going to each taillight assembly. There should be NO continuity between any of the wires with the bulbs removed. After that, check for continuity to ground on each of the same wires, with the bulbs still removed. Once again, no continuity is normal.

If all the wiring checks good, and each circuit illuminates properly when jumpered to the ground, then your RECM must be at fault. Don't despair, as I saw several in the $50-75 price range on eBay. As cheap as I am, I'd troubleshoot the wiring conclusively before replacing any modules, but that's just me.

 

Did you pull and check the fuses?

 

Are they in the trunk by the battery?

 

I'll try to check this weekend in a friends garage..weather is a little wet here lol. Thanks .let ya know.

 

Yes!!

 

Thanks..first jag..only had it for a week...a lot different than what I'm used to.

 

Good point! I should have included that in my earlier epistle.

 

Don't be intimidated by the difference in how the circuits are controlled. Instead of a bunch of separate switches directly controlling power to the bulbs, Jag uses a remote module that controls the bulbs via their grounds. That's about it. The same basic rules of electricity still apply.

Keep us posted. My Theory du Moment(tm) is a dual filament bulb has shorted between the two circuits within, blown one of the fuses (Thanks Gus), and is causing all sorts of weirdness with the other circuits.

 

Earlier today I took all the bulbs from one side and moved to the other and vise versa...was still the same

 

Big red flag when you found that added jumper wire. I would not trust any of the electrical system at this point.


Remove all the interior panels in the trunk so you can see the wires. You might have another home made repair somewhere. Cars that have been botched are the hardest to repair because you most likely have several problems.
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Great news!!! It was a fuse! Thanks guys!