Zuvell

So I have a 94 Camaro Z28 v8, that since replacing the waterpump the fans are not kicking on, period. We have tested the fans, and they work. If gounded directly to the body they do not. When running the OBD tester there is a weird humming noise that wasn't happening before, the fans still do not kick on as they did before. The noise stops if the PCM fuse is pulled or the wire going to the IAC on the Intake manifold. The vehicle takes 30 mins to overheat and pouring water on the radiator does cool it off via the temp guage, so other then a toggle switch (which im tired of hearing about as the cure all to everything) does anyone else have a clue what could keep my fans from kicking on? P.S. Its not the thermostat in the water pump as I have replaced that twice now thinking the first replacement was bad..

Zuvell

Fans are also not coming on while AC is on, though running heat does keep it cooler longer, and the vehicle shuts off before it gets too hot and still no fans even at 260 degrees

Injuneer

Any codes when you scanned it? The PCM monitors the fan control relays and the coolant temp sensor in the water pump. What sort of "tester" did you use? If it's the type that shorts the ALDL pins (e.g. - Actron 9001), it won't work on a 94 (93 was last year you could flash the codes on the SES light). But it would cause the fans to come on, and if they are jammed, might explain the humming noise.

Not clear why touching the idle air control (IAC) motor on the base of the throttle body would eliminate the hum. There is no common wiring to any other device. Is it possible you mean the throttle position sensor (TPS)? That does share a common ground wire with the CLT sensor.

Is is possible you damaged the CLT sensor in the water pump when you replaced it? That's what the PCM uses to control the fans.

Shoebox has good info:

4th Gen LT1 F-body Tech Articles

4th Gen LT1 F-body Tech Articles

Zuvell

It is possible or the new one was bad, how would you test that?

Zuvell

and the humming is comming from that motor though i dont think thats related i think it might be the cause of my original shut off issue though, and what kind of scanner do you use in the 94 i just have one of the little black ones that supposedly makes the dash flash lights but no lights flash...

Injuneer

You have to read what is posted. One of the Shoebox links tells you how to test the coolant temp sensor.

You need an OBD-1 Auto Xray scanner, or one of their OBD-1/OBD-2 scanners. Or get the free download of Scan9495, linked in a thread at the top of the "Computer Diagnostics....." forum, then buy a cable. The two best sources of ready-made cables ar described in the thread.