Hello fellow Jagnuts... my 1987 S3 V12 won’t start, tracked issue to fuel pump and main relays not having 12v power to the T30 on either relay. Traced wire from each T30 on both relays back and they come together in the boot/trunk before they disappear as 1 heavy brown wire thru the bulkhead behind back seats, there is no power to this wire. I believe it should be constant 12v. It is dead as a dodo... can anyone help me locate the route of that wire so I don’t have to pull out all the interior? Is there a fuse somewhere that I can check? Thank you in advance.

 

I may be wrong but I think that this wire goes to the ignition switch, which powers up the main relay and pump relay when switched on. If you look under the dash, you will see a huge rubber connector plug attaching the loom to a similar plug coming out on a short loom from the back of the ignition switch.
Test the wire to the relays for continuity, to be sure that this is where the brown relay wire ends up. Then check there are 12v going in to the switch, then see if 12v is coming out down this wire to the relays when the ignition is switched on. If not the switch is the problem, which can be quite common.

 

Yes, solid brown = 12v constant "+" voltage. I'm not aware of any fuses on the solid brown wires.

Normally these solid brown wires ....they branch out in umpteen directions....originate at the "+" voltage junction posts on the firewall. I'm not familiar with every build configuration but I'm hard pressed to think of, or remember, any of them in the boot area on a Series III sedan. The very late build cars, circa 1991-92, with the trunk mounted battery might be an exception.

Anyhow, unless you're determined to not change anything, it would be a fairly simple to re-power the #30 terminals from a different constant source, namely the junction posts I've mentioned. But there are other choices as well.

Cheers
DD