Probably too early to respond, my brain is still in sleep mode.
All I'm adding to the original cct is the Change Over contacts, these are part of relays within the remote box.
Only one relay (and therefore contacts) operates at a time.
The Normally Closed contacts inserted into the two wires maintain the cct originality - ie. Even though we have cut the line and added contacts the cct works as per normal.
My remote unit switches what ever polarity I wish to feed in.
So by using +ve, if locking, the lock contact operates, disconnecting the Earth comming thru the RH door switch from earth.
It applies +ve, thru LH door switch, both lock motors and the Arming contact in Vats, back up thru the LH door switch, thru inserted NC contact, thru RH door switches to earth. Drives both door lock motors down to lock both doors.
In the unlock scenerio it works exactly the same, but the +ve is applied thru the LH door switches and NOW goes to the door lock motors and dissarm input on Vats, thru the motors in opposite direction driving them up to unlock. (Reversal of polarity)
However the remote also flashes the blinkers, this cct has diodes to block since the driving voltage/current is derived from the remote, this remote uses a relay with dual output contacts - one for left and one for right side of the cars blinkers, mainly because the US market blinks all rear stop lights. And since this cct is connected permanently the diodes block anything being fed back when I turn left/right or have the hazzards on.
My remote is very very small and is probably as basic as you can find.
SO! Is the 87 cct shown equal to the 90 cars wiring? P.S Hows your car going.?