LED Bulb Upgrade

[The_Laird]

So do any of the interior bulbs need to be CANBUS? I'm really confused about this (not difficult, I know!)

[HPsauce]

I don't think so, but it so happens that the rear footwell bulbs that physically fit best ARE the one of CANBUS types.
e.g. like these:

[briang9]

Originally Posted by The_Laird

So do any of the interior bulbs need to be CANBUS? I'm really confused about this (not difficult, I know!)

No

[HPsauce]

Originally Posted by HPsauce

I think I've pretty much decided it's down to a dodgy main "rocker" switch

Took it out today and part-dismantled it, removing the 4 metal "bus bars" and the switch. No obvious corrosion but nothing was particularly shiny either.

Cleaned all the contact areas with fine abrasive paper including into the slots that the "bus bars" plug in and made sure all the contacts were tight. Reassembled and it's working fine so far, no "glitches" on reinstallation unlike previous inspections.

The back of the switch has 4 (5?) contact slots that the "bus bars" plug into so I suspect they probably had a light film on that was giving a poor/variable contact.

[HPsauce]

Originally Posted by HPsauce

Cleaned all the contact areas

Except I actually hadn't and it started to misbehave again.
Realised I hadn't actually checked out the socket that the loom plugged in to and that moving the unit around, disturbing that connection, seemed to have some effect. So I cleaned the connector pins (part of the switch unit) and bent them very slightly to improve contact and all now seems well.

[HPsauce]

The saga continues.....
The problem came back and I eventually bought a whole replacement unit (from our sponsors of course ) which arrived today.
After swapping over the oddness persists, so it has to be down to the plug or wiring, probably the plug.
I'm guessing the loom goes to the front interior light, but whether it's separate and/or easily replaced I have no idea. I've tried to loop and wedge the loom into a position that seems to pressure the plug into a "more reliable" position and hope for the best. Probably time to give up, at least until the weather is better and I can have a closer look at the connector and maybe get some cleaner into it?

[HPsauce]

So, His Lairdship asked:

So do any of the interior bulbs need to be CANBUS?

And Brian said

Originally Posted by briang9

No

BUT I'm beginning to wonder if my iffy rear interior light IS down to the LED's being low resistance cheapo's.

After my little problem here: http://forum.a8parts.co.uk/showthread.php?t=6145 I just swapped my spare (i.e. original) light unit back in and that now has filament bulbs.

No flickering, no oddness, just a rather (relatively) yellow light which frankly doesn't look great with a beige interior.

Now, that rear unit has some complex switches linked to the front and several electical components to control how the multiple switch settings interact. I just wonder if the unexpectedly low LED resistance is throwing something into "wobbly" mode.

I'll do a bit of swapping around and report back; might just order some CANBUS bulbs to try, they're cheap enough - a lot less than the whole unit I just bought!

[briang9]

HP, the reason I said no was not really based on anything other than I replaced all of mine with cheap ones from E-Bay, and not had any problems other than one burning out in the rear, but replaced it with an equally cheap one and things are OK again, sorry I know thats not much help

I did give up on the LED exterior side lights as they were failing very frequently, so back to normal bulbs in these for me

[HPsauce]

Originally Posted by briang9

sorry I know thats not much help

Brian, it's a lot of help.
I know it doesn't need CANBUS for the warning/signalling, the other bit is speculating about my specific cheap bulbs interfering with the electronics.

Anyway the filament bulbs went off earlier but were restored by taking the unit out and putting it back. So, back to square one I think.
Oddly the main festoon bulbs wouldn't come on with the switch, but the map lights did with theirs. Currently all working.

There's no logic to this conundrum at all.

[HPsauce]

I'm beginning to think it's a short-circuit problem of some sort, possibly related to the metal mountings in the roof space and/or crossing conductor bars in the unit.

Looking VERY closely at the lamp unit I can see some metal conductors that pass very close to each other and aren't that firmly located. Two in particular seem to be bent noticeably more by the nominal 38mm LED festoon bulbs than the OEM filament ones as the end caps have a different shape.

This design "feature" seems to be the same on both the units I now have so I've done a bit of gentle "adjusting" with my trusty pliers to suit the LED bulbs and all clearances look good and stable.
I've also made a "cardboard cutout" to cover the top of the unit (which has exposed conductor bars) to prevent them touching metal in the roof space.

So far, so good, but I've said that before.