Illumination feed

[richhaynes]

Hi all,

I recently got a 60 plate siggy (wrote off my 59 plate) and just finished wiring up my sub, dash cam, parking sensors and footwell lights. It all works fine and this time around I have arranged it so they all get their own fused supply.

However, the footwell lights were wired to the yellow illumination wire from the front ciggy socket so that they only came on with the headlights. After a scan of the wiring diagrams in the Haynes manual, it looks like all interior lights are connected to the Body Control Unit including this yellow wire.

My questions are....

How much current could I draw from the BCU before it would cause any critical damage? At the moment I'm drawing about 0.2A and no failures so far but I'm sure the interior lights circuit was never designed for such current draw and I'm worried I might damage the BCU.

Does anyone know where the BCU is? Im thinking of using a relay from the illumination feed which can then allow me draw power from the battery instead of the BCU.

Hope you clever folks can help 😆

[Jordaninsignia14]

MIND [emoji100] Blown [emoji16]

[richhaynes]

MIND [emoji100] Blown [emoji16]

Sorry. I should have noted it's a very technical question. Normally you can just fuse tap to get your power but in this instance you can't do that.

The best analogy I can think of is imagine charging your phone using the USB port of a playstation instead of directly from the plug socket. That changes exactly how you approach it.

Im happy to explain it some more if you wish? 😂

[MattG]

Well if you swap out all interior lights for LED's your current draw on that circuit will drop. And logically thinking if you plug a modern phone or tablet into cig lighter or any other socket that device will pull what ever it is able to. But as you say if you can pick up a fused supply straight from the battery all the better for some devices, just be careful not to have a device permanently switched on, eg. a dashcam with motion sensor and park monitor switched on, it will drop your battery over time as im sure you are aware

[richhaynes]

Thanks for the reply MattG but these arent LED bulbs but LED strips.

A quick run down of what I've done might help....

I have my amp wired to the battery as per usual with the remote wire going to a fuse tap in fuse 6. My dashcam is hardwired with the switched live connected to the same fuse tap in fuse 6. The constant is connected to a fuse tap in 26 or 27. The parking sensors get constant from the 26/27 fuse tap with a second wire connected to the reverse gear switch.

All that is left is the LED driver powering my LED strips which can't use switched live as that will keep them on in daytime. So I want to use the illumination wire from the front ciggy socket as this is only live when i have my lights on which is also when i want the strips to be on. The other items will draw power direct from the battery via a fuse. But this will draw it's power through the BCU which will be designed to only supply power to a few bulbs. Adding this extra load may damage the BCU in the long term and that's where I need help.

First I want to locate the BCU so I can test how much extra load the LED strips add. The Haynes manual doesn't say anything about its location but it does tell me which pin the illumination wire goes to on the connector.

Second I'm hoping someone might know something about the BCU who could say it's good or bad to add the extra load. The strips use SMD 5050 LEDs and there is approx 100 across all the strips. My maths gives me a 0.24A load which sounds small but it still might be too much to draw from the BCU. Any info on the BCU would be much appreciated

[Butt0ns]

Have a look here, for location. electrics beyond me.
https://opel.7zap.com/en/car/g09/p/12/20-0/

[richhaynes]

Have a look here, for location. electrics beyond me.
https://opel.7zap.com/en/car/g09/p/12/20-0/

Thanks buttons. Didn't realise it was made up of several components. I got the impression that it was a single component from the Haynes manual. Once Ive found where the yellow illumination wire plugs in, I can do the relevant tests pretty easily. I'm just hoping the one right in the middle isn't the electronics unit ive seen sitting underneath the gear stick as that's going to be near impossible to access!

Im understanding why they did this now. The interior lights stay on even after u remove the keys and fade out after u close the drivers side door. This would be difficult to do using pure electronics. Having a kind-of computer makes it simpler. The issue now is that those outputs will have a limit on the current it can supply. Trying to draw too much current could burn out the BCU circuitry. Without any specs or datasheets (which im never going to get) then I'm totally screwed on what the limits are.

[asktoby]

I have 4x LED strips in the foot wells and run them off the switched live using a piggyback fuse in the glovebox. Sure, they run in daytime, but because it's daytime you can't see, so that's fine with me.

[richhaynes]

I have 4x LED strips in the foot wells and run them off the switched live using a piggyback fuse in the glovebox. Sure, they run in daytime, but because it's daytime you can't see, so that's fine with me.

That's what I'm doing now. Even though things seem fine connected to the illumination wire, i cant take the risk of damaging my BCU. Unfortunately that means when I'm parked up and I want my lights on then I need the ignition on. This also powers up my amp which I don't want to happen.

Luckily I'm decent at electronic's so I have a plan. I'm going to use a relay so they can be powered direct from the battery. When the illumination feed goes live it will switch the relay and provide a live battery feed to the LEDs. It's the safest method I can think of.