If the car has 12v+ for your parking lights, leave the red and RED / white wire togather hook into 12v+: The parking light input wire is just the input source to use to turn the parking lights on(If the car had a neg 12v for parking lights, you would ground the red wire.
The purple and brown wires are an either/or type of thing. If you have a neg door trigger use the brown and cut the purple wire(prob. what you have). If you have a positive door trigger use the purple and cut the brown.
Don't have to use the domelght supervision wires.
What kind of alarm is it???
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Did that work???????
-Installer-
Okay, here we go. I will list your alarm wire colors first and your car wire second.
Connect the white parking light wire to the green wire under your fuse box.
Connect the BLACK/ white wire for horn output to GREEN/ red wire in your steering column
The RED / white (12V) wire connects to the white wire in your main ignition harness
Ground the black wire to metal.
connent the brown (-) door trigger wire to RED / white wire in the instrument cluster
the yellow ignition wire connects to BLACK/ white wire in the main ignition harness
All you have left is to cut your starter wire and connect the starter interupt. From your diagram, you will need a relay to accomplish this. You can find that info in the relay section of this site. Good luck and test all wires with a DMM before connecting them.
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Do it right the first time