Ignition - Ignition Relay, UK (78-on)

Hover over a wire to confirm the colour

Updated January 2010: This version is on 78 and later cars, several circuits having been removed from the ignition relay and put back on the ignition switch, possibly because of problems with relays sticking on. However the fuel pump is still on the relay - not ideal if it sticks on! Also it doesn't explain why North American spec cars only had one ignition relay wiring arrangement where the relay powered everything except the fuel pump, overdrive and ignition warning light.

Note 1: There are three separate green circuits - the original circuit fed from the 2nd fuse up in the 4-way block, and two others each fed by their own in-line fuse - one from the white/brown circuit off the relay contact feeding the cooling fan switch, and one from the white from the ignition switch feeding indicators, heater switch, tach, and heated rear window switch. These fuses are located below the fusebox, probably with the hazard flasher fuse which has brown wires both sides. The cooling fan fuse has thicker wires both sides than the one for tach, heater fan, indicators and GT HRW.

Note 2: There are three separate white circuits - one from the ignition switch feeding the ignition relay, coil (via the ballast resistance) and the in-line fuse for one sub-set of the green circuits, another in the rear harness feeding the fuel pump, and the third feeding the ignition warning light, these last two off the white/brown circuit from the relay contact.

Note 3: There seem to be two separate white/brown circuits - one from the relay contact to the fusebox etc, the other from the coil white feeding the in-line for the heated rear window etc.

Note 4: The schematics show the original rectangular Lucas relays with W1, W2, C1 and C2 terminal numbering, but in practice cylindrical relays with ISO numbering were fitted. The relationship is as follows:

Wire colourOriginal numberingISO numbering
White from ignition switchW185
Black earthW286
Brown 12v supplyC230
White/brown to ignition powered circuitsC187

The physical arrangement of how the white, white/brown, coil ballast resistance and white/light-green wires are connected together can be found here.