Hey guys im kind of new to this and ive got a problem with my electric fan. I have an 84 firebird trans am with a carbureted 350 it was switched from fuel injection to carb by old owner. My problem is with the electric fan. The car has a new thermostat new temp sensor new fan relay. the fan works if given direct power. the car is overheating and the fan doesnt engage.

Is that because the of the ecm. i have a bunch of wires which due to the conversion are not plugged into anything anymore. Does the ecm have anything to do with it? If so whats the best way to fix this without going for a mechanical fan? I previously had two wires connected at the relay bypassing it in order to start the fan as soon keys are in. for some reason i cant figure out which two it where i tried probing 1 have 2 wires giving 12v all the time and 2 give out nothing....

 

Welcome to TGO.

Do you have a repair manual yet? The wiring schematic will be helpful.

Are you getting battery to the fan? Check the circuit.

Is the pigtail to the fan switch intact? The switch provides ground at temp for the fan to be powered by the relay. Chances are the fan switch connector is either missing, cut or commonly cooked. The fan switch is located just below and between #6 and #8 on the passenger side head.

Depending on how much hack and wack the previous owner did to the harness, you might best plan on building your own fan wiring circuit. It's easy to do and you can configure it to run off of a toggle switch or to be triggered by a temp sensitive fan switch. Depending on how you want to wire it, power can be provided via hot in run or constant hot.. either way, add a 30 amp relay and fuse.

Good luck

 

I am getting power up to the relay ... Pigtails are brand new came with the new relay I bought ...

What does that fab switch relay look like any pictures I'm not sure if I even have one...

Does the computer on board the car have any effect on it or the whole system with the car heating up then the thermostat opening and the fan turning on not related to the ECM?

 

Here's what a fan switch looks like: http://www.summitracing.com/parts/JET-60601/

It's located on the passenger side head between #6 and #8. In your case, if the motor is a early model engine transplant it may not have a fan switch. Use a mirror to see if there's a plug in this location.

The purpose and function of the fan switch is to provide a ground for your fan. The switch provides a closed circuit loop or path to ground when the engine's coolant reaches 195+ deg. it activates the fan. No computer involved but the switch must be wired to the relay.

As mentioned, you can provide the ground by building a manual toggle switch for the ground path or install a temp activated fan switch if the head has the provision. This can be wired directly to the ground side of the fan if the wire is missing.

Hope that helps