Fans not coming on when expected.
Fans are set to come on between 225-230 degrees. ECT sensor sends coolant temp to PCM, PCM controls fan relays, fan relays control the fan motors. Power for fan motors comes through a fusible link and closed contacts of fan relays. Power for relay coils comes from ignition switch, and through fuse #6 (under hood). PCM applies ground on control leads to relay coils to operate relays. Single fan uses 1 relay, and 1 control lead from PCM. Dual fans use 3 relays, and 2 control leads from PCM.

(A) Turn AC ON
1) If fans now work, fan circuitry is good from PCM to fan motor. Problem is between ECT and PCM. Go to part B.
2) If fans do not go on look for trouble between PCM & fan motors
Look for bad, shorted, or grounded wiring, bad fan relays, bad connectors, bad fan motors.
(B) Turn AC OFF
1) Disconnect wires from ECT sensor and strap pins on leads going to PCM with a 50 Ohm resistor. This simulates high temp and the fans should go on. Do not short leads directly to each other in order to protect PCM.
2) If fans now go on, replace ECT sensor
3) If fans do not go on look for problem in wiring from ECT sensors and PCM

 

I have a question though.What would make my fans come on right after startup no matter the temp?

 

Is your AC on or off? Whenever the AC is on, your fans will be on. Try turning the **** all the way to OFF and starting the car again.

 

What does ECT mean?

 

ECT= Engine Coolant Temperature sensor. This sensor is used by the PCM to know the temperature of the coolant. On some engines such as the LT1 there is a separate coolant temp sensor (sending unit) which drives the temperature gauge.

 

Ok, ive changed my therm, my temp sensor, my ECT, the relay, and fuse. Yet the fans still will not come on unless I unplug the temp sensor switch. You have any ideas for that? Also I dont have ac in my car.

 

how high is the temp getting, start up a thread, include the year and what motor you have.

 

If the temp sensor is plugged in and fan not running... It will go till engine blows. With it unplugged and fan on... 185. i did start a thread, no info yet to help me.

 

First post on this site, new to the camaro scene, somewhat experienced in the car world. Anyhoo, I'm having trouble with an overheating issue with a '96 V6. None of the fans turn on.. at all! I've tested the ECT wires (good). Changed the ECT for good measure. Jumped the fans directly (good). There is no power to the wires that connect to the fans, there is only ground on the A/C fan. I'm thinking the relays might be bad, but to make sure I want to jump the fans straight from the underhood fuse box (where the relays sit). So does anyone know from where I can jump it? I've been searching all through the web but came up empty handed. So if ANYONE can please help me it will be EXTREMELY appreciated because I've ran out of ideas.

 

Hmm... I just found out that by disconnecting the ECT the fans kick in on full blast, both of them. Now I'm confused.. since this is probably a camaro specific thing, does anyone know what that means? What is this testing, or bypassing? How can I fix this annoying little problem? Anyone?