Hi Guys,

As you have always been so helpful in the past, I thought I would try again.
I have had horrendous electrical problems, but finally using the SSD software and a guy who knows how to use it, I now have an XK8 with NO error codes (a rare beast), and I thought I was home and dry, until I used the centre switch pack.
This has the DSC switch/Both seat heaters/both front and rear fog lights. When pushed all the switches turn on the appropriate item BUT, none of the small led's light up, all the blue bulbs light, but no led's.
When the rear fog light button is pushed the rear fog lights come on but no led.....hence an MOT failure.
Looking at other forums this seems to of happened to quite a few members but nobody seems to have a remedy.
Checked all 98 fuses and all are ok, and don't think its a fuse, as all the buttons run the item they supply. Removed every relay and moved them round the car and refitted in different locations......no difference. Took out the switchback and stripped to pcb, been over it with a magnifier......no damage no breaks.
Thought it might be a bad earth, so pricked the black earth wire into the plug, with a wire and multi meter back to the battery lug, and got continuity so obviously not a bad earth.
I was going to buy another switch pack (even the used one's are expensive) but one of the forum guys did that and it made no difference.
I disconnected the drivers seat module and inspected the pcb, looks perfect, so reconnected....no difference, then today disconnected the passive alarm under the front wing....no difference.
As I say when you put the ssd software on and scan, nothing shows up, so that's now the limit of my expertise, so if anybody has any ideas I would be grateful.
Bob

 

The indicator lights have a 12v supply separate to the fog lights themselves so check that supply with a test bulb. The electrical guide will tell you which fuse/relay.

If that supply is ok and you still have the switch pack out of the car, try putting 12v to the indicator supply and ground the individual indicator connectors (that go to the BPM). You should be able to get them to light up. Do this with the switch pack out of the car to be on the safe side.

This way you'll find out if it's the 12v supply or the switch pack - it's not the BPM as the lights themselves are working.

 

Hi,
Sorry for the delay in reply, you are so right, my son in law got the drawings, as that's well out of my pay grade. He is back next week so will have a look, he said it goes back to the BPM, which turns on the relay once you push the button, but the signal back to the led isn't there, so till he gets back he suggested unplugging the BPM for 5 mins then reinstalling. He said you can flash a BPM, but its a risk if it fails then you have to replace both that and the security module, but lots to check (wiring et,. ) before we do that.
So thank you so much for your help, as now it doesn't look like the switchback .
Regards
Bob

 

It's not the BPM if the fog lights themselves are working. Do not under any circumstances mess around with it unless you want to buy a new one. 😁

It's either the fuse, the wiring or the switch pack, but it isn't the mysterious black box.

 

Hi,

Ah, understood, thanks, will leave the BPM alone, I have bought a switchback, so that should be here next week, so won't do anything till I try that, at least that way I will know one way or the other. Did check all 98 fuses, and also rearranged all relays, but no joy.

Regards

Bob

 

All leds have a common +12V source - the no 6 fuse in the driver side fuse box (5A). The ground comes from different places, before and after BPM, so that cant be the problem.
Check fuse again, and check if you have 12V out of the fuse, and in the connector on the switch pack - the brown/red wire at the pin 9 (at least for the 1999 and 2000 model, that is the color)

 

Hi,



You are definitely a man with the xk knowledge, I went through so many Jaguar wiring diagrams but could not find that plug, so again many thanks. I have put a couple of pics on, so, put a meter on the 5amp fuse and got 12.49v, then on the switchpack plug, I couldn't determine pin 9, so again have put a pic on and I'm hoping that pin 9 is the one with 12.1 v, if so then it surely it must be the switchpack, but if anybody will know...it'll be you. As I said the ordered switchback should be here next week.

Once again, thank you so much for all your help.

Bob

 

Hi all,

Well what a surprise, new switchpack arrived, plugged in, still exactly the same, switches operate the seat heaters and fog lights but no led's. I am now thinking somehow to run a feed from the rear fog lights to the switchpack area to try and put an led somewhere near the switch, that'll look lovely, but I am just getting sick to death with it now, and just hope if I can do that the MOT guy will pass it like that.
Anybody have any other ideas.

Bob

 

I've just checked the 2003 EG and it agrees with the wire colour and fuse positions from the earlier versions that NorXKR gave you. (Jaguar occasionally moves things around to check we're on our toes)

The B+ from the fuse must be getting out at least part way as it's also a feed to the KTM.

I've added some pin #s to the shot of the circuit board you posted.



Re-do the check for B+ on pin 9 using a test bulb rather than a digital multimeter, then perform the checks with the switch pack that dibbit suggested above.

 

Cant believe it, thanks to you putting the extra PIN numbers on the pcb picture, and sitting down calmly, on the previous picture of the plug I did, it was upside down !! So now looking at it properly PIN 9 has not got any voltage to it.
So now it comes down to tracing it back to where there is voltage. My son in law who is an auto electrician (working at Copart on all JLR vehicles) and sorted out all the original problems I had, said he will come over when he's back and try and trace back to where the supply stops.
Once again guys many thanks, I'll keep you posted.

 

Deggo,
I think you were right the first time, or pin #9 is second from right on the top row.

Can't you probe the red & brown wire at the plug?

 

Hi, oh blimey yes you are right, the first pic is right, I was quite happy last night as I thought all I had to do was trace a wire, anyway I'll wait for my son in law, to investigate, but thanks for the correction, is this ever going to end, I luv the XK8.....but it is testing my patience now.

 

I would still test the switch pack (either or both of them) on the bench to see if the LEDs are even working. Mine are quite dim, so it wouldn't surprise me if yours are in fact dead.

Also when you are testing the fuse, leave it in the holder and probe the little contacts on the top of the fuse itself. Both positions should show power (ideally using a test bulb rather than a meter).

If all you want to do is pass the MOT, then just wire a bulb up run from the fog light itself. I don't think I would even bother trying to fix the indicator LEDs myself at this point - it sounds like way too much hassle for something you are never going to even use.

 

HI Guys

Well my son in law turned up tonight to see if he could sort the "no led's in switchback" problem. ran the ssd software, and said the software would not communicate with the BPM, so removed the glovebox and unplugged the BPM for 5 mins, reinstalled, but no diff.
The BPM is not sending the earth evidently, but as he said the car is seeing the module or nothing would work.
He also said he did not want to re-programme the BPM, as flashing it could work, or it could wipe it, which would mean a new BPM, and possible the security module as well, and seeing that both of those is getting on for £700, and as the SSD software is not online, it would need a dealer to prog.......I said, no enough is enough, I will run a wire to the switchpack and run a separate led from the rear foglight.
A shame as he said Copart had the laptop with SSD and was online, but is so old it was now never used, so it was wiped for the new software JLR used now.
Incredible to think all the problems and expenditure (getting on for £600) all stem from letting the battery drop below 12 volts while in the garage for months.......now trickle charged 24/7 so that will NEVER happen again.
So thank you guys for all your help with this bloody problem, but at least now this week will see an end, not the end I wanted, but still an end, then the MOT, and I get my life back.
A.T.B.
BOB

 

I'm not really clear now what is working and what isn't, but it would be insane to try flashing any module to try and fix this problem. Just running a new wire is the easiest fix.

To clarify though, are both front and rear fog lights actually working when you press the front/rear buttons on the switchpack and it is just the indicator lights that don't work?

 

Hi,

OK at last ran a wire from the rear fog to the switchpack, very, very carefully drilled and milled a slot in the top of the switchpack, then in with a 3mm red led, put it all back together and at last I have a red led for the fog light so can go for the MOT next week.

What's working and what's not, on the switchpack they all work apart from the front fog lamps, so that's the DSC-ok / pass heated seat-ok / front fogs-no / rear fog-ok / driv heated seat-ok / hazard-ok.
Also programmed key fobs, and red light by gear knob works but no chirp,
Also when you dead lock the car no external sounder (Fitted a new external sounder )......boot unlocks with fob and headlights go on and it locks and dead locks but no chirp. Unplugged the security locking module under the fuses in the boot, left for 5 mins , plugged back in no difference.
So I assume its all to do with the BPM, but as my son in law said although the SSD software won't communicate with it, the car sees it or you couldn't run the car.
Anyway, as I have never used the front or rear fog lights, and my **** will tell me if the seat heaters are on, its fine
Tried everything else and it all works, the end of a very, very long saga.
Thanks so much though for all your advice.....you're obviously a man who won't give up on a problem, as is my son in law, but I can get on with life now...........assuming it passes the MOT !!
Cheers. BOB

 

Well done and thanks for the update - I do like this kind of rage-fixing - if it works, it's a good repair.

BTW there is a simple wiring change you can do, to make the front fogs into daytime running lights - might be worth looking into.