Fans not coming on

[vicsponjr]

I tried the search and had no luck.

I have a 03 GTP 3800 super charged
My wife was driving the car and the said it started to get hot in traffic, then something blew and had steam from under the hood. They let it cool down and added water to try to get it home. Car got hot again and they pulled off the road and got towed home.

When I looked the front coolant elbow was gone. I replaced both elbows with the metal ones, filled and bled the system, ran the engine at idle and its still getting hot.

Thermostat (190) appears to be opening but the fans are not coming on. I turned the AC on and fans still did not come on. Took the car for a quick spin and the temp came down. As soon as I parked the temp came back up (235) and still no fans. Turned the car off and started walking away and the fans came on! Started the car again and the fans turned off. Turned the car off and the fans came on again and ran for a few minutes.

[nik12937]

You're certain it's actually getting hot enough for the fans to turn on? They have a pretty high turn on temperature stock. Then again, since they don't come on with the A/C I don't doubt you.

The first thing I'd do is check the fuses and relays for the fans. Test the relays to make sure they're actually switching and providing current flow. You can at least rule out the fans and wiring since they do come on. To me it really sounds like a relay.

If they check out, check the coolant temperature sensor (located under the thermostat housing) and the wiring that goes to it. I believe yours is a 3-pin style, so even though your dash is getting a reading, your PCM may not be.

[Scottydoggs]

unplug the temp sensor, if the fans turn on your temp sensor is bad.

also check the short harness to it, its like right on the cross over pipe's heat.

[vicsponjr]

Thanks guys. Temp sensor. I think I remember reading that that would also cause that low temp code. I had that too.

[CTKGP09]

these temp sensors can be tricky, one half goes the gauge, the half that since you can see it wont break, and the other have goes to the PCM, the side that always breaks -_-

[vicsponjr]

Haven't had a chance to check the sensor yet but I checked advance auto for the part. There was only one review and the person says "it failed to kick the fans on". Has anyone ever had this problem with an aftermarket sensor?

BWD Engine Coolant Temperature Sender

Part No. WT3024P

[Scottydoggs]

oh, forgot to tell you. it seems temp sensors can and are bad right out of the box a lot. your best bet maybe get a acdelco, or get one at the dealer. it will be acdelco from a dealer.

[BillBoost37]

Any part can be bad out of the box or good. I'd toss in an aftermarket w/o worry.

[vicsponjr]

Haven't had a chance to check the sensor yet but I checked advance auto for the part. There was only one review and the person says "it failed to kick the fans on". Has anyone ever had this problem with an aftermarket sensor?

BWD Engine Coolant Temperature Sender

Part No. WT3024P

[Scottydoggs]

like we said these sensors are hit or miss. seen threads where guys had to change it 3 times till they got a working one. warrantied of course. but a pita for sure to have to change over and over.

[vicsponjr]

well i pulled the harness off the sensor and started the car. both fans came on high speed. Kept watching the gauge to see where the temp lined out. After reaching my head into the window the second time to see a cold temp I remembered the sensor had two purposes lol. Guess I have to let it warm up and then pull the harness to see if they come on and the temp comes down.

[Scottydoggs]

temp gauge shouldn't work if the sensor is unplugged. unplugging it and the fans come on confirms the sensor is bad.

[vicsponjr]

Plugged the sensor back in, started the car to let it warm up and now the fans are working. Left it running for a helluva good time, took it for a ride, let it sit idle again. Temp is not going above 200.

[BillBoost37]

I think the fans come on as a default if the sensor is unplugged. Which doesn't confirm the sensor is bad. It merely means the pcm is seeing no sensor and kicking on the fans.

[Scottydoggs]

theres always a chance the plug or the temp sensor terminals were dirty and taking the plug off and on cleaned it enough to work again.

or the harness has a bad spot and moving it made it connect again. so keep a eye on your temps for a while.