www.jec.org.uk

Hi
Does anybody know why the led's on the centre switch panel does not work? The seat heaters and rear fog light work but not the leds. However the front fog lights dont work from the button and the head light levelling switch also does not work

I took the panel out and found the dsc led was open circuit where all the other leds are reading 10.5 k ohms so thought that might be the problem on buying a used panel from a breakers, have still got the same problem. Even the same led is showing an open circuit. There is power going to the switch board on pin 9 and the illumination lights work as does the hazard light switch.
The front fogs themselves work by bridging the relay so wiring looks good. I also swapped the relay but that made no difference.
So i am thinking it must be the open circuit led or the outputs not working from the body process module. I would appreciate any help on this as it is an mot failure to not have the tell tale lights working for the rear fog lights
Regards
Steve

Interesting problem, Steve! If you're not using the relevant wiring diagrams you may not be aware that there are more than one grounding arrangement involved here. As is usual in the X100, the systems use Switched Grounds rather than switching live wiring.

The two fog lights are intended to come on when their switches connect the Red/Blue on pin 15 and the White on pin 19 (that come from the Body Processor Module) to the Black ground wire on pin 16, but only when both ignition and dipped headlights are On.

The front and rear fog State LEDs are fed a permanent battery supply from pin 9 via two resistors of unspecified value, but only come On when they are grounded through the Orange/Green on pin 18 and the Blue on pin 20. These two wires come from the BPM and are also switched by the BPM but only when both ignition, dipped headlights and fogs are On.

The DSC LED is also fed from pin 9 via a 560 ohm resistor, but is grounded through the Red/White wire on pin 11 that connects to and is switched to ground by the Linear Switch Module that is on the LH side of the J Gate and is part of the gear selection arrangement.

Headlight leveling is totally separate from all this! Lets go there later!

To make sense of all this you really need to consult the relevant wiring diagrams. Fortunately, they're easily accessible here:

http://www.jagrepair.com/images/AutoRep ... xk2003.pdf

DSC is covered by Fig 6.1, front lights by 9.1, rear in 9.3

Hope this is of some help, but come back with how you get on.

Hi Astromorg

Thanks very much for your reply. I do have the current electrical drawings. I have checked the ground pins and they look ok. The only thing that does not look right is the open circuit on one of the leds. Normally you should see some resistance across the terminals as can be seen on all the others. Just wondering if this is open circuit, maybe breaking the circuit to the rest.
The buttons for the dsc,seat heaters and rear fog lights do work but get no led. Front fogs dont work from the button so dont see why this is different
If you notice on the next post, he had exactly the same problem. I have asked for the outcome but had no reply.
Do you think the body process module could be at fault? Although everything else works from it

If you have 12v at pin 9, then running a temporary ground wire in turn from pin 18, pin 20 then pin 11 should light up the three State LEDs in turn if they are serviceable.

Similarly, grounding the Red/Blue wire and the White wire from the BMP would bypass the switches should switch the fogs On.(Assuming ignition and main lights are On

An open circuit on the DSC line should not have any effect on any other circuit, but could be indicative of a blown LED or a burnt out resistor.

Hi Armstrong
Found the problem. It was fuse 3 in the engine compartment. It was the alarm sounder that tripped it. Disconnected the alarm sounder, replaced the fuse and now all working again.
Regards
Steve