The signal between the temp. Sensor and the PCM are not triggering the relays, apparently.
If you have A/C, turn it on and see if you have low speed fan operation with the engine running. CAUTION: Be careful about not tangling with the serpentine belt, while you are feeling for the air in front of the alternator's location.
This is a good time to have the diagnostics performed rather than guess and pay for parts that, when replaced, don't solve the problem. Check continuity between the coolant temp. Sensor connector and the PCM Harness connector with a Volt-Ohm Meter (VOM) set to 20k ohms and the PCM fuse removed from the fuse block in the engine compartment. Also check the PCM's ground wire usually attached to the ignition coil bracket mounting stud. (Your Z28 may be different.)
DO NOT energize the ignition circuit or any PCM-related sensors, at any time while testing for continuity of the PCM circuitry or PCM wiring harness connections! Permanant and VERY EXSPENSIVE damages may result.
If you DO have a faulty PCM; chances are, it is going tho be a $1.50 voltage feedback resister, the ONE that receives the signal from the coolant temp. Sensor, and sends that signal (with a revised value) on to the PCM logic circuit FOR INTERPRETATION, that probably needs to be replaced by a electronics tech and you'll get your PCM back for about $130 because they don't have an exchange program, and you get to park your car for the 2 or 3 weeks it takes for turn-around.
Better hope that isn't your problem! :(
Thursday, September 5th, 2019 AT 4:26 PM