Note: You must use a diode in one configuration or the other, or you will get a continuous current drain through the courtesy light, buzzer and parking lights, even when parked with the lights off. Polarity of buzzer (if polarity sensitive) and diodes are shown for negative ground cars, for positive they should be reversed.

Inset 1: This avoids cutting factory wiring but causes both passenger and drivers doors and the courtesy light manual switch to sound the 'lights on' warning. NB. Miles Bannister has pointed out that the original schematic for Inset 1 didn't include the diode and this would result in the drain referred to above. My (weak) defence is that I have never used Inset 1, I only included it for those people that didn't want to cut a factory wire. The diode solves the problem. Thanks Miles. If the diode is accidentally reversed the buzzer won't work, but you will get the drain referred to.

Inset 2: This arrangement results in only the drivers door sounding the buzzer. The diode prevents current flowing through the buzzer to the ground from the passenger door switch, and it is this that causes the buzzer to ignore the passenger door. It must be inserted between the drivers door switch and the branch to the courtesy light. To avoid cutting into wiring you can make up a diode with two bullets and an additional 2-way connector and insert it where the wire from the drivers door switch joins the wires from the passenger door switch and harness at the 4-way connector behind the centre console. NB. Darren Lewis has just (September 2004) advised me that originally (and for the past four years!) the diode was shown connected the wrong way round for the negative ground car shown. It is now correct. Thanks Darren. If the diode is accidentally reversed the courtesy light will only respond to the passenger door, not the drivers. And although the buzzer will work you will also get the drain referred to above.