Simple electrical question
 

Let me start off by saying that I have barely a basic understanding of electrical systems in general so please excuse my need for help on this one...
I was starting to chase down a parasitic draw on the battery today when I noticed the trunk light does not turn off. Yup, that's it and I now know that little bulb can drain a brand new battery in about 4 days.:rolleyes:
With the switch in the insulated (depressed or hood closed) position, the light stays on. If I remove the switch entirely thus leaving the ground wire floating free, light still stays on. Wiring is all original, intact and in great condition. I can't find an alternate, unintended ground.
What am I missing?
Thom

Grounded through the frame of the lamp holder.
Pull the lamp as a stopgap until you repair or replace the assembly for the switch that isn't working.

+1

Here is where I am confused... I don't think it's the switch because if I remove it, thus interrupting the ground, the light stays on. http://forums.pelicanparts.com/uploa...1462742094.jpg
I think, but may be entirely wrong here, the light should go out once you remove the switch as the circuit is no longer grounded.
As a test, when I do this to the door swtich, interior light goes out as expected.
http://forums.pelicanparts.com/uploa...1462742241.jpg
Am I just completely clueless regarding circuitry or is there something wrong here?

just take the bulb out for now and see if that takes your drain away.

On mine, PO must have had some body work and shop severed the line.

I could not locate the line so I tapped the line from the cab's glove box and it works perfectly.

I know this does not help your situation but if push came to shove, I would consider that as a bypass if you want trunk light to work properly.

The only thing I can see is that the line for the switch may be frayed down the line making contact to the chassis ergo completing the circuit.

As already stated, the switch is not the point of ground. The red plastic? washer on the switch prevents it from being the ground point. I would think that it is more than likely that the switch is the issue.

There are 2 brown/white wires to the light fixture, one goes to the switch, the other to the burglar alarm. Only the switched wire should work the light, the other wire is either shorted to ground or the alarm controller is kaput. If you don't have or don't intend to use the alarm, cut this wire at the light. I don't think it is your switch as clearly you removed it from chassis and the light was still on (getting a ground path from the other wire).

What happens when you remove the single white wire from the switch? Your photos show the switch removed from the body but none with the white wire being removed.

Good question. When I disconnect the switch and leave the wire hanging free and With no contact to the hood the light still stays on. That probably indicates a separate ground point?

Yes, that switch wire is making ground somewhere down the line or the wires connected are incorrectly connected by someone.

I'd do what timmy and the guys say and pull that bulb until you can fix the problem. That's the part of the frunk harness that can short to ground and BBQ your entire dash wiring.

Did a little searching and found this: How do I turn off the light in the trunk? - Rennlist Discussion Forums Read the second post.

In short, the light will not go out even if you push in the button if the trunk lid is open. There is a micro switch in the trunk latch which keeps the light on. This thread is about a different year 911, but may apply to your situation. If so, that might rule out the trunk light as the parasitic draw.

Thanks ossiblue, looks like that doesnt apply to Carreras. I fully closed the hood with my phone inside and video recording.... light still on.

As Steely Dan wrote, the brown white wire goes to pin "MK" of the burglar alarm connector,
which most likely serves as a sensing point should the alarm be "active",
and someone is trying to open the trunk.


As Draco wrote, the black wire goes to the glove box light, then the ignition switch.

Remove the glove box light as required for access/disconnect the black wire.

If the trunk light does not go out, then you have a short in the harness,
or the trunk switch is shorted.

http://forums.pelicanparts.com/uploa...1462831057.jpg

Good luck,

Gerry

Please pull the fuse or disconnect the battery before removing the glove box lamp. It will short to the dash if given a chance to do so!
Once removed, then proceed with testing with fuse in place if you choose to.

Thanks Dennis, fuse is pulled while I figure this out. I really would like to avoid a smokey dash!

Thanks Gerry! This is great! I will try this tomorrow.