I need to trace the wiring for my electric auxillary fan for the tow rig. Its running hot and the Aux Fan is not kicking on. I replaced the relay without results. Does this hook into a temp sensor somewhere? The truck is an 88 3/4 ton 2wd Suburban with a 454 TBI. Thanks for any info you may have. Also - M_J, what is that software you have with wiring diagrams? I'd like to purchase a copy if you think its worth the money.