Hey all,

I've been having issues with my rear running lights not working. I took the car to the local shop (Curry) and they told me the security module is not giving enough power the the lights, so I need a new module. I just checked online and the cheapest I've seen this module was $700! I've heard of a fix on this forum but I cannot seem to locate it. Any assistance or suggestions (cheaper ) will be greatly appreciated!

WhiteXKR - I wanted your convertible top install today but I'm going to have to wait and see the outcome of this.

Thanks,

Tim

 

I just looked at the electrical diagrams on the JTIS. The JTIS only goes through 2003, but I'm assuming the wiring is the same for the 2005. It seems odd to me that the security module would be the cause because the wires for the left and right taillights pass through the module separately, and it looks like they only go through the module for the purpose of detecting bulb failures. It's two completely separate circuits which split right after the tail lamp relay in the trunk fuse box. In other words, the tail lamp relay is the last point at which a single fault could cause all tail lights and the side markers (the red lights on the side of the bumper) to stop working. After that point it is two independent circuits.

Actually, now that I think about it, there's an internal connection in the fuse box that goes from the tail lamp relay, then to a joint where the circuit splits, and then to two fuses, one for each side. I guess the problem could also be in that connection. I'm going to post the wiring diagram here shortly. Be right back...

 

OK, here's the wiring diagram. I tried to highlight the pertinent wires, but I'm apparently not smart enough. Anyway, I circled the relay and fuses at the top of the drawing. If you'll follow the wire out to the right of the relay you'll see where it splits and goes to two separate fuses. Logically, it seems to me that the fault has to occur prior to the split because after the split the wires are two completely separate circuits, and it seems unlikely that both circuits would go bad at the same time within the security module.




You can test the security module by simply bypassing it. You can get some wire taps at an auto parts store which will allow you to tap into the wires without having to cut them. Just make two little jumpers and jump from one wire to another as shown by the little red segments I drew on the wires next to the security module. Or, if you have a meter you can just see if there's voltage going into the module on those wires but not coming out.

If it turns out that it is the module, I think I would just permanently install the jumpers, although that might cause a burned out bulb indicator on your dash. I'm not quite sure how that feature works. Either it would cause the burned out bulb indicator to be constantly on, or it would cause it not to come on when you really had a burned out bulb. If it was the latter, I think I could live with that.

 

LOL... The image is waaaaayyyy too small. Sorry. Let me try to fix that. BRB

Try this. Maybe this will be more legible.

 

I agree with Sam that it is unlikely to be the security module.

I sent you a PM.

 

Here's something easy to try; I think all of the relays in the trunk fuse box are identical. Just swap the taillight relay with one of the other relays and see if the taillights start working. That will at least eliminate the relay as a possibility.

 

Good suggestion. I have the correct spare relays with diode suppresion if you need one. I purchased a big lot of these, so I can give you one no charge if it is what you need.

 

Hey guys,

Sorry for the long delay but I'm in the middle of moving and the wife needed some assistance.

So you both were right the problem wasn't the module I described above. It was the module that is underneath the fusebox. I was getting considerably low power from both driving lights. The guy at Curry's found a simple and cheap solution. He wired the running lights into the taillights and completely dismissed the module. I now have all my lights working but unfortunately the "check rear lights" is still showing up in the dash. I'm ok with my lights functioning this way until I gather up the courage to pay $800 for a new one.

WhiteXKR - I'll give you a call tomorrow.

Thanks alot for all the help!

 

Try going to car-part.com that is a great source for used parts. Another thing to try is look on Ebay & look for someone parting out a car. I have found many parts from people listing something unrelated to what I wanted, they are usually the ones who show just a picture of the car but are listing just a single item. Here is an example of someone I would contact.


97 98 99 00 01 02 JAGUAR XK8 CONVERTIBLE ROOF ASSEMBLY | eBay

 

Here are some pics of my predicament.

Thanks in advance.

D.

 

The easiest way to fix would be to source the complete (or a section from the end of) the SLC Module harness and splice it in.

Alternatively, the spade terminals for those black 16-Way connectors are available and you could rebuild it if there's sufficient slack in the harness to allow for cutting and fitting new terminals.

Graham

 

Hi

Firstly sorry about the late reply, I never got any notice about your reply. That would be my first choice for the fix, but so far I have only found entire harnesses for sale, not just the end clips. And that seems pretty drastic for what should be a simple fix.


There is not much slack, but I am sure I can free up some more.

I have re-posted this same problem again as a new thread, so will see if anybody out here has apic of their harness for me, and that should be a good start.

Thanks again.

D

 

I'd answered your post in General Tech Help and moved it to XK8/XKR forum before reading this one!

Rather than repeat it in this thread, here the link:

https://www.jaguarforums.com/forum/x...wiring-103511/

Graham