I had an issue with the front boot light. This generally doesn't work but I have seen it on once in a blue moon. The bulb was fine when swapped with the rear boot and my multimeter was saying zero volts. Also, the alarm wouldn't beep if locked with the boot open. I suspected the microswitch in the locking mechanism. Before buying a new one, I investigated.
The methods outlined below are correct for earlier 986s with manually (cable vs electrical) operating front boots, but should be fairly similar to later cars.
Again, this is only a guide. Caveat emptor, you are your own warranty.
You'll need socket set with 10mm head, a flat head screwdriver, fine nose pliers and maybe some silicone spray.
Open the boot. Notice the dead light. There's a plastic trim held in by four plastic screw-like fasteners (one's missing on mine...). These unlock by turning them 90 degrees so the 'head' is horizontal. You can then pull the trim off.
DSC_0655 by ash_ashy_mo, on Flickr
You'll be greeted with this:
DSC_0683 by ash_ashy_mo, on Flickr
There are a couple of fasteners holding the front of the boot carpet in place (one's missing one mine...notice a theme? ). These come off with some twisting and pulling.
I didn't take any pictures of this, but the latching mechanism is held in place with two 10mm bolts. Loosen these. There's a metal backing plate / cover that sits behind the mechanism.
DSC_0678 by ash_ashy_mo, on Flickr
You should be able to remove this with the bolts loosened. Remove the bolts completely. There are a couple of cables and an electrical connector that need to be removed.
Remove this one first. Just prises out with a flat head screwdriver. Be careful not to damage the rubber bung.
DSC_0677 by ash_ashy_mo, on Flickr
Undo the electrical connector behind the boot carpet that leads to the mechanism. One side just simply slides off by depressing the ends and pulling. The other (below) is clipped into the front of the boot. The bit of plastic in the middle (this is the side that is clipped to the car) need to be prised away to unclip the connector from the car.
DSC_0674 by ash_ashy_mo, on Flickr
Once this is done, you should be able to squeeze the rubber bung and cable / connector through towards the front of the car and pull it through
DSC_0675 by ash_ashy_mo, on Flickr
Disconnect the second cable. This is clipped at two points. Be careful not to cause any damage.
DSC_0673 by ash_ashy_mo, on Flickr
You can now remove the latch mechanism.
DSC_0657 by ash_ashy_mo, on Flickr
The microswitch and actuator cam are beneath a black plastic cover (with what look like a couple of philips screw heads at the bottom), which is clipped to the mechanism at the top. Unclip this and pop it out:
DSC_0664 by ash_ashy_mo, on Flickr
The issue was obvious. The cam is spring loaded and should close the switch without any assistance. However it doesn't:
DSC_0670 by ash_ashy_mo, on Flickr
This is what it should do (and close the switch):
DSC_0669 by ash_ashy_mo, on Flickr
Connect the microswitch back to the plug in the boot and you should be able to turn the light on and off my moving (and assisting) the cam to the closed and open position.
The microswitch and electrical connector can be easily prised out with a flat head screwdriver:
DSC_0671 by ash_ashy_mo, on Flickr
I bent the metal actuator slightly with some fine nose pliers so the cam would have less resistance. I also lubed the cam with silicone. Once the switch and cam are assembed back together, ensure the cam now closes the switch without any assistance.
Refit the microswitch assembly to the latch mechanism and fit the whole this back to the car (reverse of removal). Don't bother with the trim panel just yet. The light should now be on. Close the latch mechanism manually with a screwdriver to ensure the microswitch is operating correctly and the light goes out.
DSC_0679 by ash_ashy_mo, on Flickr
Close the latch mechanism manually with a screwdriver to ensure the microswitch is operating correctly and the light goes out. Make sure to push the latch all the way so it closes
2017-04-22_05-42-24 by ash_ashy_mo, on Flickr
This is a good opportunity to test the boot release still works correctly. The latch should release and the light should come back on.
If all is well, close the boot. Check the level of the boot - you may have to loosen the bolts on the latch mechanism to adjust the height so the boot closes flush with the bumper.
You can test the microswitch is working by dropping the boot but not pushing it down. Try locking the car and the alarm will beep, indicating something isn't close. Unlock with the central locking and close the boot properly. Lock again and you shouldn't get a beep.
Total cost: £5 and some pennies for the silicone spray (you may not even need this!)