Hey guys, posting this for my bro. He has an 86 Iroc with a 305 TPI motor. Just finished a head swap and the problem is the fan does not turn on at all. The temp climbs up to 240 and higher on the gauge. His car has a single electric fan. Since his car is an 86, there is no sensor in the passenger side head. His fan is controlled by the ECU via the Coolant temperature sensor located in the intake manifold.

We think the gauge is pretty accurate because he has a 180 degree thermostat. Once the temp gets around 190 on the gauge, we can see coolant starting to flow in the radiator with the cap off.

The fan does turn on when the AC is turned on. Doesn't that mean the fan motor & relays are good? We have checked all the fuses and they were all good, even the fuse in the fenderwell. Things that have been replaced are the coolant temp sensor and the coolant temp sensor pigtail. Any ideas here? He really needs to get his car running again.

 

Try putting one in like belongs there, and hook up that unhooked wire that's dangling around over there somewhere to it.