Timer harness
Pink - RPM signal
The ignition feedback (IGF) signal from the igniter would be my guess for this one. This can be found at pin 7 of the big ECU connector. Pin 7 is the 7th wire on the top row of the connector counting from the left (wire side of connector). It's a
GREY/
BLACK wire.
Yellow - Lamp
Again I'm guessing, but I would think this would be wired to the lighting circuit to dim the illumination of the timer when the lights are on. You should be able to take a feed for this from the radio harness, or any of the switches in the dash that light up when you turn the lights on.
You can find an illumination feed at the
DARK GREEN wire in the grey connector of the radio harness. There's a light green and a dark green, make sure you take the dark green wire.
Green - Handbrake
Connect this to the wire that runs to the switch at the bottom of the handbrake lever.
You can connect in here at the multiplug behind the drivers kick panel. It's a
Yellow/
RED wire.
Orange - ACC
Wire this to the wire from the ignition switch that has 12v when the ignition switch is in the ACC position. It's likely to be a thin wire, not one of the heavy wires.
Use the
BLUE/
RED wire from the back of the ignition switch.
Red - Battery live
Wire this to a live that has 12v regardless of ignition switch position. You can probably wire both Red wires together, but if you do this I would fuse this wire as close to the connection as possible. A 10a fuse would probably be safe enough.
Connect the end of this wire to a 10 amp fuse and then connect the other side of the fuse to the big red wire from the timer relay module.
Black - Earth
The obvious choice for this is to put a ring terminal on the end and bolt it to the body of the car somewhere, preferably an earth point.
Grey
Like you say, the obvious choice for this is to wire it to the Grey wire coming from the relay module.
Relay Module
Blue - KeyON
Wire this to the wire from the ignition switch that has 12v only when the ignition is ON.
Use the
BLACK/
YELLOW wire from the back of the ignition switch.
Red - Battery live
Wire this to the wire on the back of the ignition switch that has 12v regardless of ignition switch position.
Use the
WHITE/
RED wire from the back of the ignition switch.
Yellow - Aircon
TBH, I'm not sure what this needs to connect to, but it's probably not needed so wouldn't worry too much.
Hopefully that should get you on the right track mate and don't forget to disconnect the negative terminal from the battery before you start, your playing with a lot of high current wiring here and you don't want to go shorting something out.