My alarm works..at least when I unlock the doors using the rotary on the inside of the door with the windows down.
I found the light in the trunk by the right hinge where Adrian said it would be ..it was disconnected. I plugged the connectors for the light together and it came on.I couldn't find the switch anywhere. didn't go out when I closed the trunk. was independant of the interior light however. I could get the interior light to function correctly by running a wire from the door operated side of the light to ground..light would go out when I broke the connection to the chassis.

So..the interior light fix should be relatively easy..but where is the switch in the trunk? and does that have anything to do with the alarm?

 

I can help with this one. The switch is on a metal plate right under where you found the light. If you had to reach down in there to connect that 2 prong connector together then you practically had your hand on the switch.

 

Dear Slant,
I had a similar problem. Couldn´t find the switch. The reason I could not find the switch was because it was missing. It had broken off and fallen into the hood/bonnet/trunk lid.
If you look at the hinge you will see that there is a threaded hole, the rubber boot may still be in place. You may well find you already have something in this hole. A threaded hollow device. It is hollow because the switch has fallen out. The light is always on because the wire on the switch is permanently at earth. If you play around with the loom which goes into the lid you will find this wire. The switch is not hard to replace but ensure you put the little red gasket on the new switch before you install them. Also beware that when you ask for the rubber boot which covers the switch (maybe you did not see this rubber boot on the hinge) you will most likely get a 993 one and they are no good. Too tight,
Ciao,
Adrian
911C4

PS: These switches are really mickey mouse.

 

I have my C4 in the hangar right now thawing out. I decided to check this trunk light, interior lights issue to be 100% sure. I can confirm that on my 1989 C4 the trunk light does not activate the interior lights.
So I would like for my own research the types and model years of 964s that this does occur on. This maybe another one of those USA only or UK only things but it does not show up in the wiring diagrams,
Ciao,
Adrian
911C4

 

I couldn't find the hood switch last night..as Adrian has suggested I will look at the hinge itself in search of a missing switch.
I've already verified the functioning of the interior light so I just need to run a new wire to the swithes on the doors and that should take care of it. So far it is not obvious to me on how to run this wire. Perhaps someone has done this before?

at that point I should be able to verifiy whether the hood, the engine cover and the interior lights work together..I can't believe they would intentionally be that way. for that to happen you would need to have the same wire running from switch to switch so that when one made ground they all do.

Why would the designers want all the lights to come on at once?

 

Good thread!

Adrian, fyi, with 92 C2 Cab, interior light comes on with either trunk or eng compartment lids open. Also, not dependent upon light, I've disconnected my trunk light and the interior light still comes on.

Again, with these cars, some of the workings are as much an art as a science!

Monty Willis
92 C2 Cab
Top down and lovin it in P-cola Fl

 

Dear Monty,
There are some things with Porsche that you just have to accept. Learned that lesson. Eventually with research you can find out exactly what is happening but I have done it so many times I have to stop otherwise I will never finish my book.
Ciao,
Adrian
911C4

PS: I will make mention of this that in some set ups the trunk light sets off the interior lights. Still cannot see the connection in the wiring diagrams though.

 

I know this is an old thread, but I have searched and searched. I still cannot find the luggage trunk switch. Does anyone have a picture or page from a workshop manual they would care to post? It is dark and late on the East Coast and it may be right in front of me, but I swear I cannot locate it. Thanks in advance

edit: by the way, it is a 93 964 cab

 

The front trunk switch is attached to the trunk lid itself. If you are standing at the front of the car and have the trunk open, its on the your left, next to the hinge (US passenger side). The switch looks like the switches at the doors that turn the interior lights on.

 

On my '93 cab the switch is combined with the latching mechanism. If you look down into the latch, you will see the plunger.

 

Fou, I have a picture but I don't know how to post it.
I send you an email.

Greetings,

Alfred
The Netherlands

 

[QUOTE=Adrian;149300]The trunk switch has no impact on the interior lights.

On my stock unmodified Targa: the opening of the trunk & engine compartments turns on their lights and the "interior light". This happens when the interior 3 position light swich is set to turn on when the doors are open. That's how I know if I did not close the boot properly.

Cheers
Walton

 

My 1991 turns on the interior lights when the boot is open; same as you.

 

For those who may be interested, I found it. The light switch for the luggage compartment on my 93 cab is located under the hood latch assembly and attached to it. You need to take off the plastic shrouding that runs the length of the inside front boot by turning the two plastic screws to get to it. It is not on the hood itself or at the hinge as some have suggested. Maybe mine was an update for the later years.

You can turn off the light by tricking the latch into thinking the hood is shut.

Also, on my 93, the interior lights will come on if the hood is (or thinks it is) open.

Now, does anyone have a theory as to why my overhead interior light stays on, but at a faint glimmer, after the doors and hood are shut and closed? It shines bright when a door or boot is fully open, yet darkens almost to a flicker after shutting it up and waiting 30 seconds.

Could it be the door contacts not disengaging the ground like some have suggested, or any other thoughts?

 

FIXED. If anyone in the future has this problem, and you discover your door switches are in good working order, check the wire that runs to the luggage light.

Where the wires come up from the bulkhead near the luggage light, it is attached by two clips to the hinge itself. Because that is a spot prone to bind, or be displaced by items in the trunk, make sure the wires have not separated over time and grounded out. My ground had slightly poked out of the insulation and was making a very small contact with the body, therefore grounding just enough for the light to flicker. It was draining the battery until eventually the light burned out over time.

Reinsulate the wiring with a good quality electrical tape and fixed.

I suspect that is also what was causing problems with the central locking. Instead of the computer being wacked, all is fine now that the ground wire is fixed and the alarm computer can confirm all doors and latches are closed.