Trunk/Engine light stopped working at same time

[ramblinmike]

Hey Guys-

I just searched for an answer to this weird situation and didn't find anything.

My engine compartment and trunk lights just stopped working at the same time. Both are grounding just fine but there is no +12V in either location. The glove compartment, interior door lights, and door lights work just fine.

On the schematic it looks as though all of the interior/door/trunk/engine/glove compartment lights are all tied together and run off of the same fuse.

Is there a place that the trunk and engine lights are tied together other than where it shows on the schematic? A plug that may need to be cleaned?

Thanks,
Mike

[WelmoedJ]

Not sure if it's related, but...
if you have an alarm system installed, there could be a connection for the alarmsystem.
In my car when opening the trunk the engine bay lights turn on, regardless the lid is closed.

You also could have a disconneted +12 Volts in the trunk feed (check behind the grille).
It also may be two disconnections at the same time (the one I mentioned here afore) and a broken or disconnected engine bay light switch.

Pick your choice.

[ramblinmike]

Welmoed - thanks for the reply.

Well, I don't have an alarm so that's not the issue. ;)

I pulled the trunk light switch out of the hood and checked the terminals at the trunk light switch. Neither is getting +12V. I also tested the switches themselves with my multimeter. Both are working fine.

That's why I was hoping there was a connection somewhere in the harness that was shared by only these two lights since everything else on that same fuse appears to be working.

I've never had the grille off, but I can check and see if that connection you mentioned is just dirty. Now that I type that, I'll check the engine bay harness plug as well.

I still think its odd for both to happen at the same time.

Mike

[WelmoedJ]

Welmoed - thanks for the reply.

Well, I don't have an alarm so that's not the issue. ;)

I pulled the trunk light switch out of the hood and checked the terminals at the trunk light switch. Neither is getting +12V. I also tested the switches themselves with my multimeter. Both are working fine.

That's why I was hoping there was a connection somewhere in the harness that was shared by only these two lights since everything else on that same fuse appears to be working.

I've never had the grille off, but I can check and see if that connection you mentioned is just dirty. Now that I type that, I'll check the engine bay harness plug as well.

I still think its odd for both to happen at the same time.

Mike

You mentioned checking at the switch's connections.
Behind the grille there also are single wire connectors for the wires to the switch.
I had one of those disconnect at one time, so that could have happened to you too.

The switch in the engine bay will disintegrate after so many years.
It could be that the switch internally lost contact (either by disconnecting the top: kind of "exploding" or internally breaking).

And yes, the wire loom connectors near the coil may also be the cause of no power in the case of the engine bay light (either corrosion or pin/socket being pushed away).

[Bitsyncmaster]

I had that same thing happen once. So there must be a common connection for the trunk and engine lights somewhere. I don't think I found what caused it (fixed it self).

[ramblinmike]

I guess I Ieft one detail out of my original post.

I just replaced the radiator, installed braided stainless brake hoses from SpecialTAuto, a new thermostat, and a new brake master from DMCH.

I was just in those places, but the only wire harness I touched was when I unplugged the fans.

[Tillsy]

My engine compartment and trunk lights just stopped working at the same time... The glove compartment, interior door lights, and door lights work just fine.

Can you jump in your DeLorean, close the door so the interior lights turn off, and then reach up and manually turn on the front interior light.

I reckon you will find nothing happens...

[ramblinmike]

Nope. Checked that! The glove box light works as well. :(

[ramblinmike]

I went out and checked fuse #12 just to cover all the bases. I unplugged it and both interior lights went out.

When I get some time tonight I'm going to look for a bundle of purple wires in the visible harness in the relay compartment. It would make sense that the splice between front and rear would be back there somewhere.

[DMC5180]

Hopefully you will find the issue inside the car. Their is, however, a Main Harness to Forward harness connector inside the Washer fluid reservior area. You have to drop the tank to acces it. For the Engine light Pull the associated BH connector and prob for power/continuity.

[Ron]

Did you happen to bring power to one of them and see if the other worked too?

[Bitsyncmaster]

It would be great if someday someone with an old removed harness could take it apart and document every location of every splice. That way we would know where to look for bad joints.

[Tillsy]

Nope. Checked that!

Bummer - as you hadn't checked the fuse yet I was figuring perhaps it was blown and that a PO might have messed with the three diodes in your driver's footwell and thus your interiors were still functioning via positive feedback from the binnacle.

[Tillsy]

When I get some time tonight I'm going to look for a bundle of purple wires in the visible harness in the relay compartment. It would make sense that the splice between front and rear would be back there somewhere.

Found it for you whilst doing some other work - it is located on the passenger side rear centre console.
http://dmctalk.org/attachment.php?attachmentid=21129&d=1376205689