As if I haven't enough to get resolved on my problematic 2003 XJR, I was about to drive it in the rain and turned on the headlights and got the "CHECK REAR LIGHTS" message. It may seem odd that I had not seen that before but since I've not been able to clear the other codes yet; (P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308, P1316) I don't think I ever drove the car with the lights on. I've had the car now about six months and put less than 300 miles on it just trying to get enough miles to pass inspection; then the codes come back and I return home to try again to resolve the problem. (More on this in another post.)
I checked the voltage at the tail light pin on the schematic and the voltage is very low with the connector unplugged and even lower with it connected to the tail light assembly. I then traced the taillight wires back to the body processor and they were both intact so I don't think it's a broken wire, (or wires since neither light will illuminate and they have separate feeds) I also checked the fuses to the BPM and of course they are intact. Just to get the light to work, I have jumpered the power wires from the side lights to the tail light connector so the tail lights at least come on but of course the message is still displayed. Of course I could just live with the message but it's a distraction plus I don't like anything to be wrong with my cars. ( I would leave the wires jumpered if I could stop the message though)

So here's the question: What could be wrong outside of my BPW just being broke? If so, is there somewhere I can get it repaired in the USA? Or does anyone in this forum have one from a wrecked car that may be available? The car is a 2003 JXR-R and the BPM code on the trunk tag shows BPM. LNG2500AC/046
Of course something else being wrong and easily corrected would be the most welcome news!

Thanks again for the kind advice from such experienced guys! Best, Dave

 

I recall several people resolving this issue by connecting a separate ground wire to the housing. Search this forum and the X100 forum and you should find a couple of threads.

 

" voltage is very low " ....................using a good meter lead ground test point and not the lamp assembly ?

Your running tail light ( marked ) should be related to the headlights on command

Bad lamp assembly ground is common from reading

If it comes to a BPM they have to have the correct software , so not plug and play

There is a software # under the front engine hood near the windsheild

 

Lamp earths can be measured with current also. But there is ofcourse possibilty of broken slcm module. I'd measure the rear lights ground connections and then sent the slcm for repair if needed. My slcm had bunch of broken solder joints on it. Joint's are small so they can not be seen with naked eye. I would think that any car module repair shop may be able to resolder bad joints if you give them what pins lights are connected. That is if they want a job outside of they mainstream line of work. I sent mine and it came back fully working. I did repair before sent to repair ocassional check rear lights message just by resoldering the all of the big light control transistors. I did look in to the grounds and bulb housing connectors first ot course.

 

What a fantastic document markup Parker! I will make sure the ground is secure though all the other lights work fine; DI, Stop, Reverse & Fog. Thanks for the document and advice.....

 

I did open the BPM and saw the heat sinked transistors around the outside rails. I took the meter and tried to ohm out the brake light pins to find the corresponding transistors but could not find any continuity from pin to any transistor or the relays. It would be quite possible though that the transistor output is not directly connected to the wire as a direct short may cause it to pop. There are a couple of relays in there too that might cause the switch from the "lights on" command. A schematic of the box would be handy to have too!
No harm in a solder tough up to see if it fixes the issue. I'll attempt that next time I'm fooling with the car....

Thanks for the handy tips!

 

I get the same message on my 01 when I hit the brakes, but not every time, maybe 30% of the time I apply the brakes. Double checked and all bulbs are good, the brake lights are illuminating when the message is displayed so I haven't dug in yet.