Front Trunk Light- What's going on ? - 986 Forum - The Community for Porsche Boxster & Cayman Owners

jim_hoyland · 01-12-2010, 03:58 PM

I got a headache; the front trunk light was out. So I thought a simple bulb replacement was needed. To be sure, I took the bulb from the rear trunk-it works-and tested it in the front trunk. No Dice

Out comes the multimeter. The front trunk light plugs into a red and yellow wire. Tested them without the light and get 12 volts; yellow wire has continuity to ground; my conclusion is there is twelve volts to the light. When I plug the light back on, NADA. Interestingly, I do not get 12 volts at the light connectors either.

The light unit works fine with a battery and works fine in the rear trunk.

Anyone been down this road ? It doesn't make sense to me.

Paul · 01-12-2010, 05:14 PM

Probably the switch in the front hood latch, what year is your car?

jim_hoyland · 01-12-2010, 06:54 PM

It's a 1998 I thought it might be the switch originally too. But, the voltmeter shows 12 volts at the + red and - yellow wires that connect to the light.

I also tested a spare license plate light. NADA again. Everythig I see tells me the light should be working.....but, I'm missing something; what is it ?

BoxsterS21 · 01-13-2010, 01:58 AM

Mine is the exact same way. I have an 02

jim_hoyland · 01-13-2010, 05:32 AM

Searched the Renntech forum on this and didn't find anything other than lubricating the latch mechanism so that the light switch ( microswitch) works properly.

The switch must be working if the red and yellow wires read 12 volts; interestingly, if I use the cars ground instead of the yellow wire, the light will work.
And, the yellow wire showed continuity with the cars ground....

The Renntech forum indicated both front and rear come on together---don't know if this is true, but if it is true, could there be somthing else going on ? I'll revist this again today....

chaudanova · 01-13-2010, 01:11 PM

interested in this topic as well. Mine used to work fine, and now seems to be taking a break...

jim_hoyland · 01-13-2010, 02:15 PM

For those whose front trunk light is not working, I would like to know whether you get a 12 volt reading when the red and yellow wires are attached to a multimeter. The red is + and yellow is -; disconnect the light light unit from the plug to do the test. I get 12v

Paul · 01-13-2010, 03:36 PM

Guys you are reading a phantom voltage, probably due to a bad ground somewhere.

You need voltage and current to light a bulb.

Check the switch since it most likely provides the ground.

Paul · 01-13-2010, 03:39 PM

What happens if you try to lock the car with the trunk open?

jim_hoyland · 01-13-2010, 07:18 PM

When the bulb is inserted and the red/yellow tested-No Voltage

I'll try locking the car with the trunk open tomorrow...

SeanZ4 · 01-14-2010, 05:43 AM

My trunk and frunk lights come on separately. I pulled my frunk bulb a few weeks ago to hook up a batt. tender. I hope it comes back on?!? I was going to just "push in" the latch to make the bulb go out. I was afraid I might try to close the hood on the latch and damage it so I just pulled the bulb. Hummmm???

sean

gerrygug · 01-14-2010, 07:56 AM

Mine does not work as well. It's a 2000S
Where is the switch located?

jim_hoyland · 01-14-2010, 08:38 AM

The microswitch is located within the latch assembly. If you do a search on the Renntech Form under 986 Boxster with the search words" front trunk", there is an article on how to replace just the microswitch. The latch assembly has to be removed to do this.

SeanZ4 · 01-14-2010, 08:38 AM

I have a 2000 S as well. I believe it's in the front latch assmbly. When I was trying to decide as to whether to remove the bulb or not I was able to push the latch assmbly down and it turned the light off.

sean

jim_hoyland · 01-14-2010, 06:10 PM

Paul:

Tried locking the car with the front trunk open; the doors lock like normal, nothing else I couls see or hear.

As tried locking with rear trunk open; same thing.

Paul · 01-15-2010, 05:54 PM

OK then your front trunk switch is bad since your alarm horn should have beeped when you locked the car with the trunk open.

jim_hoyland · 01-15-2010, 06:33 PM

Paul,

Thanks for the explanation. Unfortunately, my horn doesn't always beep twice when everthing is shut; but I get the idea and tend to agree that it's the microswitch.

I didn't want to go off topic, but have to ask why my horn doesn't always beep after the lights flash twice. It might beep one out of ten or 20 times when locking.

Paul · 01-15-2010, 06:41 PM

It beeps only when something is not closed.

At least the following will cause the alarm horn to beep:

front trunk open
rear trunk open
door open
glove box lid open
Roof clam shell not closed

Some of your switches may be working intermittently.

jim_hoyland · 01-16-2010, 06:04 AM

Didn't know that beeping results only fron an open trunk/door; so many cars beep when locked, I thought it was supposed to beep. I'll go back and read the owners manual. Thanks for the info-I learned something today !

jim_hoyland · 02-10-2010, 12:36 PM

Thanks for the tips and info. I found a DIY on Renntech, ordered a replacement microswitch, from Suncoast and did the exchange. The front trunk light is back.

One question though: There are two cables entering the front trunk latch, one from the right-driver side-, and one lower from the left ( pass side ). The upper one from the right looks like its attached to the manual mechanism on the door sill.
What is the lowere cable about ??? Curious minds want to know