On my 89 IROC there is a relay located underneath a panel near the hood-release handle that has 4 wires. 1 small dark green wire (pretty sure it goes to the ecm), 1 green with white stripe wire that goes to the P/N safety switch, and 2 yellow wires. My question is, where do those 2 yellow wires go? It looks to me like they come from the ignition switch, but I would like to make sure first. The wiring diagrams in the haynes manual I have are almost completely useless and do not even show this relay. The reason I am asking is that when my engine gets hot and I let the car sit for a few minutes, then turn the key to start, nothing happens. The 2 yellow wires going into the relay are only putting out around 9 volts when this problem happens.
Thanks,
Joe
89 IROC 5.7L TPI

 

You are correct, those two yellow wires are coming from your ignition switch. When you turn your key to the start position, a full 12 volts should be applied to those 2 yellow wires. With only 9 volts, you have probably narrowed down your problem to your ignition switch, or the wiring from the ignition switch to that starter enable relay.

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1989 IROC-Z 5.7L
NOS 150HP kit
ProBuilt 700R4, PI Vigilante 2800 stall lockup
Baer Brakes 12" Sport System