[rnblade]

I’m hoping you gurus might be able to shed some light on these faults.
1. The interior lighting isn’t working. The lamps are good. I’ve checked the ‘ROOM LP’ fuse and it is not blown and there was 13v at the top of the fuse. Checked the vanity lamp and other holder connections and there’s nothing!!!!
Not sure what to try next.

2. Central locking from the fob has stopped working. Doesn’t lock or unlock. Battery voltage in fob is 3.1v also tried spare key and same fault. Doors don’t unlock on removal of key either when they used to before. Doors don’t unlock on the drivers door button either. I disconnected battery for over 30 mins but same problems are there. I’ve searched a few forums and it seems there might be a barrel problem causing this. I’m going to try the “electrical spray treatment” and see how that fairs.

Any help will be gratefully received as it’s p*ssing me off immensely.

[tw2005]

I’m hoping you gurus might be able to shed some light on these faults.
1. The interior lighting isn’t working. The lamps are good. I’ve checked the ‘ROOM LP’ fuse and it is not blown and there was 13v at the top of the fuse. Checked the vanity lamp and other holder connections and there’s nothing!!!!
Not sure what to try next.

2. Central locking from the fob has stopped working. Doesn’t lock or unlock. Battery voltage in fob is 3.1v also tried spare key and same fault. Doors don’t unlock on removal of key either when they used to before. Doors don’t unlock on the drivers door button either. I disconnected battery for over 30 mins but same problems are there. I’ve searched a few forums and it seems there might be a barrel problem causing this. I’m going to try the “electrical spray treatment” and see how that fairs.

Any help will be gratefully received as it’s p*ssing me off immensely.

Curious whereabouts you are on the globe, but first thing that comes to mind is the BCM(body control module) all of the things you are talking about integrate into that. The key barrel idea is intersting so I'll test thyat idea now and see what happens. But thye lamps not working is leaning me towards BCM, I doubt key in barrel would stop those working

[tw2005]

I can confirm with a key in the ignition, the remote does nothing, but I could key lock and unlock manually with a key in the ignition

[rnblade]

Curious whereabouts you are on the globe, but first thing that comes to mind is the BCM(body control module) all of the things you are talking about integrate into that. The key barrel idea is intersting so I'll test thyat idea now and see what happens. But thye lamps not working is leaning me towards BCM, I doubt key in barrel would stop those working

I’m in Cornwall. I saw a few references to BCM in my searches so far, I am not familiar with this so what would you recommend? I disconnected the negative lead to the battery! I’m wondering if to disconnect completely and see if that makes any difference. Is there an easy accessible fuse for BCM?

[tw2005]

maybe, I'm just thinking at the moment focussing on the lamps in particular the maps. If you push the individual map to use that switch does it illuminate? I presume what you say is the momentary centre button does not activate the lamps?

Not like I've had to fault find a BCM yet either. I've done a swapout of the BCM that's it.

[rnblade]

maybe, I'm just thinking at the moment focussing on the lamps in particular the maps. If you push the individual map to use that switch does it illuminate? I presume what you say is the momentary centre button does not activate the lamps?

Not like I've had to fault find a BCM yet either. I've done a swapout of the BCM that's it.

None of the lamps work in any mode. I tried all the switches in all positions. It’s has to be something common to all. It’s frustrating. It can’t be anything too difficult surely. Famous last words.

[tw2005]

In that case I'm back at the BCM then, I'll have a read of the circuit diagram see what I can figure(if anything, LOL)

[tw2005]

[tw2005]

[tw2005]

If you're switched on electrically and have a multimeter should be easy to at least test / check what is happening with the key switch which grounds pin 18 at the BCM.

[rnblade]

Thanks so much for the assistance. This is way beyond my capability. Im not going to strip the dash etc out as I’ll no doubt damage it or fcuk it up.
Do you think a complete battery disconnection may be worthwhile, before it goes to the garage? I only took off the negative lead last time.

[tw2005]

Thanks so much for the assistance. This is way beyond my capability. Im not going to strip the dash etc out as I’ll no doubt damage it or fcuk it up.
Do you think a complete battery disconnection may be worthwhile, before it goes to the garage? I only took off the negative lead last time.

Unlikely, you disconnected gnd so power was removed. May be good idea to go somewhere where they have factory level diagnostic (dealer)because they can then enter the BCM module and possible run commands to see if it's functional or not and view current data.

[rnblade]

Stupid question coming......
If there’s a voltage at the fuse ROOM LP i would expect to get a voltage at the fitting or is there any diodes etc inline. Or is it a straight earth return cct.
I’m a bit lost as I thought this should be not too difficult as it’s only interior lighting. Schoolboy error.

[tw2005]

Stupid question coming......
If there’s a voltage at the fuse ROOM LP i would expect to get a voltage at the fitting or is there any diodes etc inline. Or is it a straight earth return cct.
I’m a bit lost as I thought this should be not too difficult as it’s only interior lighting. Schoolboy error.

well, there's two sides to the fuse so depends on how you probed this but obvious thing would be to remove and inspect fuse for blown or open cct  or if in doubt grab known good spare fuse and swap out. Of course lets assume fuse was blown and there is a fault which blew it then new fuse would also blow out.

Usually very obvious with those blade fuses, would be gaping air gap in the middle if blown and possible burnt internally.

[rnblade]

Thanks again for the idiots guide pics. I am going to change the ROOM LP fuse, even though it looks fine and good. I’ll stick a meter across it.
I’ll pick some up in the morning and make a start. Fingers crossed it’s just a bad fuse,even if it looks fine. 🤨

[tw2005]

Thanks again for the idiots guide pics. I am going to change the ROOM LP fuse, even though it looks fine and good. I’ll stick a meter across it.
I’ll pick some up in the morning and make a start. Fingers crossed it’s just a bad fuse,even if it looks fine. 🤨

If you stick a meter across it will that be at what setting? Volts or resistance? If in circuit and set to volts a good fuse will display 0 voltage drop, if it's open likely will show battery voltage, if out of cct and resistance then 0 ohms or lead resistance

[rnblade]

I’ll take the fuse out and resistance test it. At least I can replace it if it reads anything greater than leads resistance.

[rnblade]

Cracked it!!!
Disconnected battery again!
Removed ROOM LP , DR LOCK & T/GATE fuses. Visually, ROOM LP fuse looked good, but when tested out of cct, it was open cct .
DR LOCK & T/GATE fuses proved good visually & electrically.
I also squirted a bit of electrolube in the ignition barrel and worked it with the key a few times.
Refitted all fuses and connected battery, interior lighting working with exception of one map light now, which is the lamp, just need to get a replacement.
Central locking is now functioning correctly too. Locks and unlocks via all keys and internally on the switch. Took it for a short spin and doors lock automatically above a few mph.
Thank you so much for all your advice and pointers tw2005. I’ll buy you a beer if we ever bump into each other. It’s literally saved me from being financially raped by the garage.
I’m wondering if the ROOM LP fuse causes central locking issues too? Seems a bit too coincidental.

[tw2005]

Cracked it!!!
Disconnected battery again!
Removed ROOM LP , DR LOCK & T/GATE fuses. Visually, ROOM LP fuse looked good, but when tested out of cct, it was open cct .
DR LOCK & T/GATE fuses proved good visually & electrically.
I also squirted a bit of electrolube in the ignition barrel and worked it with the key a few times.
Refitted all fuses and connected battery, interior lighting working with exception of one map light now, which is the lamp, just need to get a replacement.
Central locking is now functioning correctly too. Locks and unlocks via all keys and internally on the switch. Took it for a short spin and doors lock automatically above a few mph.
Thank you so much for all your advice and pointers tw2005. I’ll buy you a beer if we ever bump into each other. It’s literally saved me from being financially raped by the garage.
I’m wondering if the ROOM LP fuse causes central locking issues too? Seems a bit too coincidental.

Nice, If that fuse tested open then that was the issue. No coincidence with the locks, that's what the BCM is all about, basically a logic controller with all the electrical side of things  and it has an antenna for a reason too because that's what the fob remote is paired to.

[tw2005]

Oh, I'm presuming you studied the schematic. probably an oversight not mentioning  ROOM LP fuse, you can see it's the power line to the BCM, you sounded like you had already figured that fuse was key.... whoopsy

Yeah so when you mentioned it , I thought you knew if that was open then no power to bcm and that then presents all the symptoms you described and why I was focussing on it being BCM out of action.

Figured you reached that conclusion , but now realise you arrived there maybe purely on the basis the lamps were not working.

Sorry, I was spending so much time trying to get the info out not giving you the checkpoints

[rnblade]

After I had a good look at the cct diagram it did make sense. Thank you so much for all your help. It’s really appreciated. No wonder the car companies don’t really like releasing source documentation, it makes fault finding so much easier.
I can see now why this is such a good site.
Thank you once again for the pointers.

[tw2005]

After I had a good look at the cct diagram it did make sense. Thank you so much for all your help. It’s really appreciated. No wonder the car companies don’t really like releasing source documentation, it makes fault finding so much easier.
I can see now why this is such a good site.
Thank you once again for the pointers.

[Dazzler]

I love a happy ending. 

Great to see all the appreciation for the help too.