@nashvegas Many thanks for all the advice . It took me a while to get back to the vehicle due to extra work shifts past few weeks, but had a look this week. I exposed the ignition module and tested for any current to the ignition illumination ring - nothing. No current at all. Thanks for the tip of transit mode - tried that as you suggested and no joy.

I've removed the drivers side footwell panel and can see the connectors (pics below), but I cannot for the life of me figure out how to pull them apart to check the wiring - can anyone advise? I'm being cautious on this vehicle as I've found a few brittle components that have crumbled. For what it's worth I see zero signs of previous damp or water ingress, so don't believe it's corrosion due to water.

I've also cleaned up all the grounds in the engine bay, not that any were really bad, but worth eliminating. (Found a few other broken/missing parts whilst doing that).

Given that the interior lights are the only real issue I'm having (other than the occasional turn signal issue) I'm wondering if I really want to tackle a failing BCU for that and instead rig up a fix somehow that will turn on the interior lights.

 

If you look at the top of the brown connector, the bottom of the grey one has a cut out that receives that piece, they slide apart. Push them apart, pull the brown away from you and the grey away. If you put a squirt of silicon spray in the junction, I find that it helps quite a bit. I would bet that there is a plastic christmas tree plug holding the modules to the wall.. you could probably just pry it off the metal, make it easier to work with. I have taken the passenger side apart a couple times, assume it is similar.

Do you have the RAVE electric manual that will have wiring diagram. Its actually very helpful. I had chased down a BCU fault that turned out to be a broken component in the BCU. You could back pin test the wires with out taking the harness apart. I was getting some voltage, but not enough, so it was a bit trickier to check. Basically I had tested every possible item multiple times, opened the BCU and saw the cracked component and found a local computer repair shop to replace it.

I have not really followed what you are doing, but I would check the power into and out of the LKM for the appropriate wires, or maybe the interior lights are controlled by the BCU? With the RAVE it will be a much easier diagnosis, knowing how frustrating this troubleshooting likely is. I think I have a pretty detailed thread here as I sorted it out.

 

@redrover75 Thanks. You're right about how the plugs are fixed to the body and how they pull apart - I got that far. The part I'm stuck on is how to unplug the plugs to check the connections inside. There must be a trick to it that I clearly don't have as I've tried to get them apart but failed. I wondered if there is a trick!

I do have RAVE and the separate wiring document. I'll admit I'm not great at reading wiring diagrams and the idea of trying to follow the wires from the headliner back to the BCM or even into the main loom of the vehicle is intimidating to say the least. I have zero experience in that area.

 

I dont recall how they came apart, I think it was obvious once I had them off the wall. I think a silicon spray would help the latch slide apart. I was in your shoes w the electric when I started. I would get or make a them probes to back test and test the voltage of the correct wires with and without the lights on, if you have the correct power out of the BCU and through the harness the issue is likely at the light itself, then just test the voltage at the light. There are people here much more experienced in electric troubleshooting, but I would just keep reading and find some youtube tutorials.

 

The corroded connector that I spoke of earlier in this thread looked perfect from the outside. I could NOT get it apart. It was seized together with very corroded pins. It was not salvageable.

 

@Havir thank you. But how do they actually come apart. There’s a small springy part on the engine bay side of each of the plugs (as opposed to the car seat size); is that relevant? I have to get them apart somehow.

 

I don’t remember the connector number, but the one on mine that was faulty was the “dummy plug” that is different for different markets (eg NAS, ROW etc). The corrosion was so bad that it would never have come apart. I ended up cutting the wires and permanently splicing them together to function as per the wiring diagram for NAS vehicles. It lives above the passenger (RH) feet. (I have no idea if this is your problem).
Most connectors of course, have some sort of plastic locking tab that you need to depress to disconnect.

 

OK, got the plugs apart. Thanks for the advice here. No corrosion whatsoever, which is as expected given the car's condition but certainly worth checking.

I'm trying to follow the wiring to fault find. I'm using the D2 electrical library document, all 700 pages of it, but I'm not really sure I know what I'm doing and so would be extremely grateful for any direction/advice. Here's the issue (forgive the length of this post):

According to the manual:


Header C0289 is shown here in this 'photo, which appears to be in the passenger footwell by the vent fan:



And following the document, C0723 is shown here:



My question is: am I reading the electrical manual properly and to verify the wires are working/that there is voltage, do I find the 'P' (purple) wires and back test? I guess that if I get voltage, then it's an earth issue. Am I on the right track?? (I'm reasonably happy with the spanner stuff on LR, but I have very limited experience with electics).

 

Well you’re up in it. The best way to do it, is exactly what you are doing, trace it wire by wire, connector by connector.

P is definitely Purple, in that manual, as you know.

Here’s how I’d start. Basic. Are you getting 12v on those purple wires ? There’s really not much to it. Think of this like plumbing. Where’s the break.

Start at Fuse 20 (which you say has power, have you REPLACED this fuse btw?) -- probe one side, do you have power?
Probe the other side, do you have power? If so, proceed to:
then C0289 -- probe one side of connector, probe the other side of the connector
then C0723 -- same here -- I think from here it then goes into 3 Purple wires to all 3 of the interior lights.

I suspect that since your ignition switch light doesn’t work, your issue is between fuse 20 and C0289 or at C0289. Maybe the wire backed out or something? I say this, because, if the issue were at C0723 the ignition light would work. And of course, there’s also the BCM. But we’re assuming you have a wiring issue right now.

BTW do your sun visor lights work when the ignition is on the run position / car is on and visors are flipped up? Does your rear view mirror dim when the car is on at night? Also related.

(PS to find the 12v -- back probe them please)

It sounds like you’ve tried to get 12v at the light switches right? Did you use a different ground than the wire coming into the lamp assembly (ground to frame of car in case the ground wire is bad at the lamp). Just making sure you don’t have a ground issue instead of a supply issue.

 

@nashvegas A quick ‘thank you!’ Been up to my eyeballs this weekend replacing brake hoses and doing Option B. Will get back to the lights as soon as I cen get a decent brake bleed…!