So we’ve tracked down our fan issue to NONE of the wiring is bad it’s all good we’re getting power all the way to they fan when we force the fan relay to click on (we took a relay apart and click it with our hands instead of the PCM receiving a signal from the temperature sensor which detects the temp telinh the PCM “ok time to tell the relay to turn on” right ?)

does this mean that the PCM is bad because that’s the only thing I can think of everything wires back to it but if we bypass the PCM by just clicking the relay with our hands through all it’s stick parts the fan turns on nothing is wrong with the wiring all fuses, relays, disable links are good ?

what do y’all good people reckon ?


Clicking the relay “””bypassing the PCM”””

 

Like anything, ECM output drivers can and do go bad; butt not all that often. The "test" you're doing doesn't "prove" anything about that. All it "proves" is, that the relay contacts and the wiring for the fan and the fan itself, are working. That doesn't test the relay coil or any of the circuitry that drives it.

Does the relay operate when there's 12V on one side and ground on the other? Is the fan sw in the pass side head connected and working? Can you operate the relay by touching the contact of the fan sw wire connector to ground?

I don't think the ECM controls the fan relay in the TBI motors, rather the fan sw does it directly, butt I could be wrong about that. There should be 12V on the brown wire w the key on, and the fan sw grounds the grn/wht wire to complete the circuit and operate the relay.

 

A TBI fan I believe has constant powerr, then the fan switch in the head grounds and closes the circuit in the passenger head.

 

Thanks for the advice and help I figured it out luckily and just bypassed all of that stuff and ran in through another relay… that’s one way to solve it probably just some cut wire somewhere I couldn’t find I tried really hard tho

 

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1227165,1227730 and 1226870 did

 

You're correct, withdrawn