My rear (RH) blinker started acting up (fast blink and warning light) in cold weather on my '04 XJR. Replacing the bulbs didn't solve the problem so I bought a used Rear Electronic Module (REM) with the identical PN# and tried swapping it out. No luck, made things worse so I am guessing it needs to be programmed for my specific vehicle. I thought this would be a slam dunk, so I drove down to the Jag dealer with my VIN# and new REM where I was told they no longer service vehicles older than 2013. I wasn't ready for that so now I need to find a place that can reprogram the REM for my car as optioned. Question is, has anyone run into a similar problem? If so, where can I send the REM for programming? Thanks in advance for any helpful suggestions.

 

I've been through similar with my '04 in the last few months (mine was also the weird tail light / turn signal behaviors with the reverse lights on, or when changing lanes with tail lights on, and also no CHMSL with the car in reverse and lights on). The REM has done some strange stuff in the past (fuel pump related), but everything checked out there this time. Prior to that, the car also had a habit of eating fuses for the 12V sockets in the consoles. The issue was narrowed down to the rear fuse/relay box (in the trunk/next to the spare and battery). I bought a used one from a junkyard, made sure all fuses were in the right places and not bad, then swapped them out. Problems solved.

Paul

 

Thanks, Paul.

I thought maybe it was the rear electronic module and since I had a spare (that I could not swap out since it needed to be programmed) I was able to determine which transistor was responsible for driving the right rear blinker relay and replaced it with one from my spare REM. This had no effect so after more forum digging I learned that bad grounds are common so I cleaned and tested the grounds associated with the REM and rear lights, specifically ground terminal G24 located near the REM but this didn't help either. So just now I bought a replacement rear fuse/relay box and I probably should have made that my first choice but no harm no foul. Here's a question... what is the difficulty level? It seems to be plug-and-play am I wrong?

 

Yep, it's basically plug and play. Degree of difficulty: Easy. 10 and maybe 13mm sockets for the box, itself and the positive battery terminal. Disconnect battery, loosen and lift box up, remove all harness connectors and the positive battery lead from the old fuse box, plug them into the new one (they're all different, so there's no way to accidentally connect something wrong). Swap battery lead, reinstall, connect battery. That's it. Taking my sweet time, the entire job took maybe 20-30 minutes.

Paul

 

Great! Thank you. Should get the new (old) part in a week or so. I'll keep you posted.

 

Hi russpe,
The REM has the processors and logic to control the circuits. The rear fuse box only contains relays and fuses. If you can isolate the problem to a particular relay, some are replaceable, and some are mounted on the internal circuit board. Even those relays can be replaced with a bit of work, and the relays are very inexpensive. There are a few threads about repairing the fuse boxes. I had to do it with my front (engine bay) fuse box. Out here at the end of the world, there are very few used spare parts available, and they are expensive, so we have to repair things ourselves. This is (or was) one of our New Zealand characteristics.

Pete M

 

Well, I must admit, the JLR electrical engineers have a strange way of doing things but maybe there's a method to their madness that I don't know about. At any rate, I think I solved my problem with the rear RH blinker. When I brought my car in for an alignment the mechanic listed some issues for me to address. The rear RH blinker (that I knew about), the high-mounted brake light wasn't working, and my HID headlights were dim. So I replaced the HID lamps and the high-mounted brake light but while I was testing them, I noticed that when I turned on my RH blinker with the lights on, not only was the faulty RIGHT-hand rear blinker barely illuminating as before but in addition, the LEFT side tail light also blinked with it! Well the REM electrical diagram shows nothing in common with those functions but then I dug a little deeper. As it turns out, the rear Left-hand tail light, the rear Right-hand turn signal, and the high-mounted brake light are all in the same circuit and being powered by relay R8 on the Rear Power Distribution Fuse Box and that relay is non-serviceable. For further proof, when I pressed the brake pedal with the RH turn signal and the tail lights switched on, the high-mounted brake light flashed along with the LH tail light and dim RH turn signal. I am currently waiting for a replacement (used) Rear Power Distribution Fuse Box but I think all I needed was to replace relay R8 or maybe it's a wiring problem from R8, either way, it looks like I'm going to resolve this. Once I get the new fuse box, I'll locate R8 and replace it on my original fuse box if I can find one on eBay or elsewhere and then post the part number and source.

 

My XJ8 I discovered had a lot of rearranged wiring in the rear which I couldn't initially make sense of......turned out that one of the fuse box system relays must have gone high contact resistance.
Unfortunately the north island auto sparky the prior owner sent the car to just tapped into a multitude of 12 volt supplies to split and run the affected tail light functions.
I pulled the rear fuse box out, split the PCB and replaced every "system" relay in one foul swoop as I have no intention of doing that job again.
Then I had to neatly put the rear loom back together as it was originally.

I guess it might have been cheaper for the auto sparky to chop apart the loom and graft everything rather than actually fix the fault that was there.....but I certainly didn't appreciate his handy work!
But the car has about 4 metres of nondescript wiring and two ugly inline fuses less in it now compared to when I bought it.

I would recommend keeping your defective unit and "refurb" it by refreshing the system relays in your fuse box as the relays in a second hand part will eventually have issues as well.
You can then swap it back into the car as and when needed.

 

Hi russpe,
Well done for tracking down the issue! Fortunately Mark (H202steam) and I have both done this for our cars. Mine was the engine fuse box.
I have attached some information on the relays you will need. They are available from a number of suppliers and are quite inexpensive. I have described the process of disassembly, relay replacement and reassembly in other posts on this subject. The relays available may not have the exact same part number as the original, but the difference is usually only the material used for the contacts. I have found them satisfactory since installation a few years ago.

Pete M


V23084

V23076

 

Thanks to Pete and Mark for your assistance and support in hanging with me on this thread. And a special shout-out to Pete for the relay info. I am an EE by trade and part of my job was to re-source obsolete electrical components, form, fit, (if possible) and function which can be time-consuming, so thanks for saving me the trouble and the replacements are probably of better quality as well. To Mark's point, one thing that really annoys me is the (well-meaning I hope) people who do electrical work with an OK knowledge of automobile wiring but have zero finess. The use of electrical tape instead of shrink-tubing, twisting wires instead of solder or splices, and poor crimps, etc etc. that may (temporarily) work for aftermarket stereo installation but is not reliable for critical functions in the long run but to be fair, I probably take it a little too far.

 

I agree and your Preaching to the choir my friend!!
Have repaired my share of "crimp" connectors that fail and even worse just build resistance internally. Then you get the great symptom that it sometimes works and sometimes it does not!
.
.
.

 

Ah yes, the dreaded crimp that measures good with a meter but fails under load, or a cold solder joint is probably the hardest electrical wiring problem to find. UGH!

 

Pete,

Well, good news! My replacement Rear Power Distribution Module has been installed and everything is working! Now I'd like to repair the original by replacing the relays BUT when I removed the circuit board assembly from the plastic housing I noticed that the relay solder connections are not accessible and that they are sandwiched between two circuit boards held together by no fewer than 81 standoffs (posts) that appear to be pressed in as well as soldered! I don't see any way to replace the relays without separating the circuit boards which means unsoldering the 81 posts is that what you did? Or did you cut the posts and then solder them back together at the cuts or am I missing something?

 

Hi russpe,
When I repaired my front fuse box, I cut all of the pins joining the boards with side cutters. I then de-soldered them all and reassembled the boards with new wire links. BUT.. with hindsight, I wouldn't do that again. What I would do is cut all the pins with a Dremel-type tool and a cutting disc. This makes a much cleaner cut than the side cutters. The cut is also only about 1mm wide. Don't forget to clean out all the conductive dust! After replacing relays, I would just solder the cut ends of the pins back together. There is a plastic spacer between the boards, so there are no alignment issues. H2o2Steam may chime in here as I think he did it this way too. When you have done it you will wonder what all the drama was. The device is totally passive, so no ESD worries.
Good luck!
Pete M

 

Ha! I'm glad it's passive because I only wear a ground strap when QA is looking :-) I will probably go with the 2nd option and re-solder the cuts but I think there is merit to both methods. Solving this was a huge relief since this gremlin has haunted me for a couple of years. So now it's on to the next gremlin, B2291 the 17-code airbag fault so at the risk of going off on a tangent, do you have any experience with this? I bought a used Occupancy Sensing Module off eBay for $30 without doing any real troubleshooting, just a scan tool diagnosis and fuse check. I understand the module is under the passenger seat and that sometimes the connector works its way loose but after a cursory check under the seat, I didn't see the module.