Is there a fuse for the rear (side) running lights on a 2002 XKR ?

Front running lights & everything else works fine including stop lights , taillight’s and tag light.

Tried new bulbs, a no go.

I have the fuse chart in the vehicle care booklet, but don’t see a fuse labeled for the rear running lights. A relay ?

Blindness is a possibility I know.

Z

Ideas ? Neither rear running light will illuminate.

PS if the fuse is #21 in the luggage fuse box, I tried replacing that one without success.

 

Ref: Fig.09.2 of the 2002/2001 Electrical Handbook. It is indeed Fuse #21 in the trunk fusebox. This fuse is ahead of the Bulb Fail Sensing feature of the Security and Locking Module which, in turn is ahead of both rear side marker bulbs which each side finally goes to Ground.
Just curious, are you getting a "failed bulb" notification of sorts? Here is a link that may help:
https://www.jaguarforums.com/forum/x...06/#post399002

 

Thank you for the reply.

no notifications on dash. Just no voltage to side lamps in the rear.

great timing, as I have no time to trace wiring for a fault, tomorrow I have to drive about 500 miles for medical evaluation. And the same mileage the following day to get back to my own bed.

I just dislike starting a trip without all bulbs working as they should. After I’m back on home ground I’ll take out the trunk (boot) linings and try to get a handle on the fault. The wires to each bulb do see some heavy duty vibration and exposure to the elements. So once I find where the voltage vanishes, I’m hoping a test jumper wire will get the bulbs to illuminate and
expose where the problem originates.


Z

 

Remember they need a live and an earth to illuminate .

 

Z:
I should have picked up in my first post that Splice BTS7 in addition to the rear side markers, also feeds to the license plate lights thru the security and locking module.
(PDF attached)
So even if you are away for home, you may want to see if your plate lights are burning, indicating that the fuse and such ahead of that splice are good to go.

 

Thank you ! License lights and fuse OK. Am getting curious where the 12v went. Can’t find out / investigate for a couple of days.

Z

 

I am curious of your findings when you do pinpoint the problem / problems. Good luck

 

Likely a little late for you journey, but if your LHS tail lamps are lit, then it's somewhere downstream of BTS7. BTS40 or SLM connector? Could also be SLM internal resistor, although I'd expect a dash warning in that case. Check if there's any voltage on the side markers with both bulbs removed.

 

the LHS tail lamps are indeed illuminated. With both rear bulbs removed I have about 4v at the bulb terminal.

all other lights are good to go. From reading on the forum it seems I might have some intermittent issue with the brake light switch. But so far no codes are thrown and no faults are shown on the dash display.


Z

 

I hope your journey was uneventful.

So, with the tail amp bulbs in place and illuminated, you get 4V across the side marker connectors with both their bulbs removed? If you replace one side marker bulb, does that drop to around zero?

 

yes on both counts.

I took a longer way on the outbound portion and ended up with 1,120 miles total on the car (and myself) over a two day period. The car did very well; most of the time I drove at 75-90 mph. The usual no drama from the drivetrain.


yes , with one rear side marker bulb installed the voltage drops to zero when checking the other side.

Z

PS I have to point out that modern automotive electrics are way above my comfort zone of understanding. That’s probably why I’ve been driving classic cars since 1966. I can fix them without getting a splitting headache.

 

Good to hear.


So there's a high resistance somewhere downstream of BTS7. The side markers have separate ground connections so less likely to be a grounding issue.

I'd measure voltage upstream from BTS40 back through the SLM to BTS7. Unfortunately that means pulling the SLM out of the trunk box to get to its connectors.

 

Reading the forum about others who have had the rear markers go away, and sometimes have or not have the “check rear lights” message, there seems to be a collective wisdom that an intermittently functioning brake light switch is the culprit …..

comments ?

Z

 

I don't see a correlation between the two other than that all the lamps on each side have common grounds.

 

I hope not. As changing he BL switch looks like a difficult job for a person of advanced years.


Z

 

I was a little surprised that you have 4 volts with the bulbs removed. (front probing in effect) I was expecting that to be 12 volts. I agree with Mike that you have a high resistance at or downstream of BTS7. Since the reading is 4 volts, I suspect a poor connection whereas there are both series (8 volts inline) and parallel (4volts produced by current leakage to ground) voltage division. Hopefully, getting rid of such a poor connection/connections would result in a full 12 volts across those marker bulbs.

 

Since splice BTS7 does feed both the side markers and the license plate lights, it seems odd that the license plate lights are functioning normally.

So I should be looking for a short or break in wiring between the BTS7 and where the power for the side markers diverge to each side ?

Z

 

Dr. D, I just printed out the rear light schematic you kindly posted. I’ll pull out the plastic rear trunk liner as soon as I can and start tracing .

I do know that both sides of fuse #21 have power, so I’ll start with module and see if the R/W wire going into it still is active.

Thanks again to all who have posted. Very valuable pointers, that are sure to save me troubleshooting time.

Z

 

I think that the problem, although being possible at BTS7, is highly unlikely as the plate lights do work, and is more likely to be somewhere downstream. I think you should be looking for both a partial short (high resistance dropping 4 volts to ground (in parallel with the marker bulbs) and also a partial break in the wiring so to speak (a high series inline resistance that is dropping 8 volts). It would surprise me if it was not all found a one location. Also, note that when the marker bulb/ bulbs are installed, the whole voltage division equation changes, thus the reason you got the zero volts across the unlit (but good) marker bulbs.
I do think that you are on the right track and I hope that it turns out to be an easy fix. I had a somewhat similar problem that to my embarrassment, took me a couple of weeks to solve.

 

The number plate lamps are on the other 5A fuse (F19) & BTS8.

Check the voltage against ground in and out of the the SLM here with the sidelamps turned on and side marker bulbs installed. Should be B+ on both: