problem with trunk pin on vw cabriolet

Hi to all, I'm wrapping up the installation of an Alpine Alarm Mod. 8063 on a '93 VW Cabriolet. Everything went fine, doors, starter cut, sensor, etc. with the exception of the trunk... The wiring of the trunk: At the trunk there's the 'trunk light" which gets only positive ( + ) when the lights are on, the ground ( - ) comes from the pin (which is the wire I tap). Now, you open the trunk with the lights on, you get a light, you open the trunk with lights off, no light. Simple, right? The problem is that: - I turned off the car with the lights off - Get off the car - Close the door - The alarm display tells me to check the trunk - Turn on/off the lights briefly the alarm display tells me that all sensors are OK - Huh? What am I doing wrong? Do I have to put a diode from the alarm to the ( - ) of the trunk pin? I'm really puzzled with this one... Any help will be greatly appreciated. ~jachong

Put a diode on the positive side of the trunk light with the band facing toward the light.  The problem is caused by a negative coming back from the parking lights when the lights are off.

Or join your trunk feed to that switch wire and use 2 diodes, bands towards switch or most simple of all, if there is a live feed in the trunk, kill the light circuit feed to the lamp and make it permanent.

Awesome! I'll give it a try tonight with a couple of 4k diodes on the ( - ) wire from the alarm to the pin. I'll let you know if this works.... many thanks! Cheers! ~jachong

Er 4k would be a resistor value what you mean is a 1N4004 diode.

Ooops! Sorry... I was thinking other values. Thanks for the clarification! Cheers! ~jachong