The simplified wiring diagram can be found here -
http://www.haynes.co.uk/forums/showt...?t=4763&page=3
I attacked my sierra wiring loom the other night to make my custom loom as per my diagram in the link above.
In total - from the sierra loom I saved -
Reverse switch connector and wiring
Brake reservoir level connector and wiring
Starter Wiring
Alternator Wiring
Column Switches & Ignition key swithc wiring.
70A master Relay
Flasher relay
Changeover relay
I cut the wiring as far back as I could in the loom.