Front Trunk Light Problem

[JimHoyland]

Crosspost from 986 forum. Rear trunk light works fine, front trunk not. Switched bulbs, then entire unit. Front works fine in rear trunk, but rear won't work in front.

Multimeter test. Disconnected the the plug from the light; tested the red (+) and yellow (-) wires. Reading says 12 volts. Tested the yellow for ground continuity; plug to body, AOK

Now, insert the light back onto the plug and test the two connectors; NADA

I've read the threads on the Microswitch in the latch; but it must be working if I get 12 volts when the light is disconnected, Right ?

Anyone experienced this ? The Boxster is a '98

[jcan]

I've got a 996 with the similar latch and similar problem. I think you'll find the latch is switching the ground, so you'll test 12v at the light. You just won't have a ground on the connection. What I did was spray wd-40 into the latch to loosen it up as it was stiff, on a side note the micro switch mechanism must have loosened as well and it now switches ground. Problem solved, hope this helps.

[Wayne 962]

So, you're saying that the two connectors show +12V and a proper ground when the bulb is disconnected? But when you plug in the bulb, the voltage differential goes away? I think jcan is right - the ground wire to the chassis is not sufficient - you need to measure 12C across the two terminals, as the switch is a switched ground switch? Check out the microswitch near the latch for the front trunk.

I got confused recently with something similar (can't remember exactly). I was measuring ground from the wire to the chassis, but not a voltage differential. In this car, I believe that the "ground" wire used for common ground to electrical devices is often not connected directly to the ground points on the chassis, but instead to a switched ground. I remember scratching my head a few months ago trying to figure something out and realizing that on the Boxster/996 it's set up differently than the older cars.

-Wayne

[Wayne 962]

The switch in the front should have a yellow/brown wire and a brown wire going to it. The brown wire is the ground, and also supplies the ground for the electric switch to open it on the later cars (but you have a 98 which has the cable pull). The switch is indeed a ground point activated switch, but the positive voltage is also controlled by the "consumer switched off" element of the alarm system (i.e. it turns all lights off after about two hours to conserve battery power).

I'm still thinking that your switch is faulty, check it across the two yellow/brown and brown terminals. The brown wire should have continuity with the chassis and the battery negative as well.

-Wayne

[Wayne 962]

Also try putting the bulb across the two wires directly. Maybe there's something screwy with the actual plastic lamp assembly?

-Wayne

[KevinH1990]

I had the same problem and eventually replaced my switch. I think the new switch was a slightly different design.

It would be great (although too late for me) if someone could think of a repair for the older-design switches. I think the replacement part was over $40 with shipping which seems like a lot just to have light in the front trunk. The reason I replaced mine is I didn't want to be groping around in the dark trying to find things if I had a flat tire.

[JimHoyland]

Update: I rplaced the switch too; it's a very easy project. And now there is light ! I used this link for step-by step instructions"

http://www.renntech.org/forums/index.php?/tutorials/article/123-front-trunk-microswitch-replacement/