Originally Posted by
rivetts
I'm changing my trunk light as well and my bulb is burnt out and I do have power to the socket. What I would like to check is if the switch is turning off the light when the trunk is closed. I don't think I can fit in the trunk. Some times the Germans over engineer things. I know you've heard that before, I didn't just make that up. I looked up the bulb on Osram Sylvania and the bulb number is 6418. The one I took out is a Phillips K25673. I know before I bought the car that it either had a dead battery or the battery was disconnected, so I would like to be able to check to see that the light is going off and not constantly draining the battery when not in use.
First of all, the idea of putting your phone in the trunk to determine what the light is doing is brilliant. (But I already knew alaxfire was brilliant, he drives a RED XF.)
Second, I can't imagine the light is draining the battery, because the switch provides a signal to the BCM, same as the door switches, the BCM in turn turns the light on and off. Remember, the lights time out, and this is how it works - there is no direct connection between the switches and the lamps, it's all done by the BCM.
The dome and trunk lights (in a Roadster, anyway) go on and off together no matter WHAT door is opened, incluiding the trunk.
And I'll award my "Post of the Day" award for anyone who can find the damn swich in the trunk that turns the light on and indicates to the BCM that the top can be raised and lowered (it appears to be the same switch). I have NEVER found that damn switch.
EDIT: What I am saying (and I'm haveing a migraine attack so I can't see well) is that the switch in the trunk tells the BCM that the trunk in open, or partly open. It is this indication that causes the BCM to turn the lights on AND to prevent opening or closing of the top while the trunk is open or ajar.