Hope someone can help.

I have fitted a new alarm to my 88 xj40 and need to find either a positive or negative trigger from the courtesy light switch in the drivers door.

Does anyone know the colour of either of these wires, or where I could tap into this?

I tried to test the wires in the light itself, but they all seemed to be permanently live.

I am getting really tired of being "auto re-armed" whilst deactivating my immobiliser.

Many thanks.

Zobling

 

No idea of colours or such, BUT, in all my years with all sorts of cars, the door switch only completes the EARTH circuit.

YES, you will see 12v on both wires if the light is ON, the circuit is "complete" so voltage flows to earth via the switch. With the light OFF you should be able to probe the 2 wires and find a 12v, and a "dead" wire, which will be the earth wire.

IF the switch has 2 wires to it, they are both earth wires, one goes to the lamp, the other goes to a dedicated earth point (bolt/screw). The single wire switches rely on the mounting screw/s to complete the switch earth, not as reliable as the 2 wire switches, but they work.

 

Many thanks for the quick reply.

I also have had some experience of alarms etc, and never had a problem in finding the required wires for the courtesy light switch.

I tested the interior light all contacts with the door open and closed, and also with the bulb out looking for continuity to earth with the door open and then closed and couldn't find continuity. All contacts showed positive 12v. Confused the hell out of me. Think there is a relay for it though, but even this does not follow the norm for testing with a multimeter.

Think I might need to take the door card off and find the switch wiring.

Many thanks,

Zobling