2003 lr discovery remote start

Hi, I'm the proud owner of a 2003 Land Rover Discovery. I want to install a remote starter and have in fact installed the starter which works ok. The problem I'm having is a negative door input wire " This input should be used in vehicles that use a negative-switching Dome Light circuit. Connect to a wire that tests ground with a door open. CAUTION! You can only use either the NEGATIVE DOOR INPUT or the POSITIVE DOOR INPUT wire. It is essential that the Module be connected in such a way as to allow each one of the Doors to be detected by the remote starter." Connect to a wire that tests ground with a door open. I do not know where to find this wire. I have tested a few and cannot locate a suitable wire. Can anyone assist with this? I have the complete wiring schematics for the vehicle but am still struggling Thanks

BCU, passenger side behind dash. Driver's door trigger PURPLE / white, pin 17; passenger and hatch, PURPLE / red pin 4; hood PURPLE / red pin 15. All NEG trigger diode together the first 2 before joining to the alarm's door trigger input, use 2 x 1N4004 diodes with the bands away from the alarm.

Wow you are quick! So I also have 4 wires for the locks etc. lock, unlock, arm, disarm. I'm thinking these will be BCU, Blue/grey for arm/disarm and Yellow/pink lock/unlock. Each wire send a NEG 500ma pulse. do I have to alter with a resitor or relay to actuate the lock/unlock, arm/disarm? Thanks!"Tell me and I'll forget; show me and I may remember; involve me and I'll understand."

I read this as pink/red NEG lock, 26 pin plug pin 16, yellow/pink NEG unlock 16 pin plug, pin 7. Using the factory alarm wires might give you problems with the factory alarm when you engage the R/S but here are the wires. I wouldn't use them. Factory arm, blue/green, NEG 26 pin, pin 5, will also lock the vehicle. Factory disarm, single pulse, double pulse will unlock, blue/grey, NEG 22 pin, pin 22. DEI give the first two as NEG but don't assume, those colours remind me of the MOTOR wires on earlier UK Rovers.

Thanks for your help. I will test these out and let you know how it goes. The remote start I have can be programmed to send a disarm pulse to the OEM alarm just before starting and then once the cycle ends it rearms the alarm. This will deactivate the immobilized too so for security I have added a starter kill relay which is passive whenever the key is not present. Hopefully the remote start will be easy to program for these options."Tell me and I'll forget; show me and I may remember; involve me and I'll understand."

Thanks for your help. I used diodes to isolate the lock/unlock etc and reprogrammed the remote start for a double pulse unlock / single lock and it works like a dream! Thanks again for all your help"Tell me and I'll forget; show me and I may remember; involve me and I'll understand."