I would like to see about getting a straight answer..ok, the problem is the cooling fan is not coming on around 220 temp..I replaced the gauge and it seems pretty acturate..heats on the gauge slowly..I replaced the sensors including fan relay on back side of block on passengers side..now, can i ground the sensor out and see if fan comes on or is that not a good idea??..no, i dont want no toggle switch lol..fan will come on in AC mode..but i want this fan to come on in the right way..so, how can i troubleshoot without buying everything on ***'s green earth lol to fix this problem?? remember..straight answers lol..thanks..Ozzy

 

the fan is NOT coming on at 220 or its not coming on UNTIL 220?

 

fan motor works = yes
new relay works = yes
sensors = ?? what did u change
fan relay on back side of block on passengers side = did u mean fan switch?

the most important one is the coolant temp sensor, did u replace that?

the fan shouldn't come right on at 220 i thought its alittle higher than that.

just to clear things up u have dual fans?

 

My '86 TPI does exactly the same thing. I've plugged in an Auto-Xray and watched the temperature reported by the computer track the dash gauge exactly. But I can let it go all the way up until its uncomfortably close to the red, and the fan never comes on. If I put the ECM in code reading mode (short A and B on the ALDL), the fan comes on. Never have figured it out, and swapping the ECM didn't fix it.

I was also able to make the fan come on by grounding out the temp sensor input at the computer, but shorting A and B is probably safer.

 

More info helps. If it's a single fan it may not come on till around 234. Dula fans have one driven by the ECM, the other by the fan switch on the pass side of the block. Single fan is controlled by the fan sw only, the ECM does not control it. The only other thing that will control a single fan is AC request. You can ground the single wire on the fan switch and with the key on engine off the fan should run. That tells you the fan is ok, the relay is OK and all wiring is OK. Since the fan does work with AC that also rules out the fan motor and relay. If you ground the wire on the fan sw and it runs the only thing is either it's not getting hot enough or the fan sw is bad. In rare cases too much teflon tape can insulate the sw from block ground, but usually there are enough threads that cut through to provide ground. Thats as straight as I can make it.