1990 Suburban wiring

Anyone here know of a place that I can go on the web to find a wiring diagram for my beast?

I have a broken wire coming out of the wiring harness at the big bunch of wires that comes out of the firewall into the engine compartment. This wire appears to be purple (bear with me - it's old, and dirty - could actually be brown) and is heavier gauge wire than the rest of the wires coming from the firewall.

Also, there is a red wire coming down from the fuel pump relay, that has a female end attached to it, but goes to nothing. Anyone have an idea what it goes to?


Thanks in advance.

Andy