Coolant Temperature Sensor

[chevypower91]

Hey guys,

I have a '03 Olds. Alero with the 2.2 ecotec and I am having issues with both cooling fans turning on when you start the car from cold and remain on until you shut of the car. I thinking that the culprit is the coolant temperature sensor, but I have no idea where it's located.

Can someone please tell me where to find it and perhaps post a pic of it;s location.

Thanks in advance

[Lucalare]

Well a thought, is your water temp gauge reading right(yes I know it would take a long time to heat up.) also, isn't there a relay for the radiator fans as well as a fuse? maybe try swapping in a relay you know works (if there is one for the fans) and see if it fixes the issue. Much easier than changing a water temp sensor.

[Lucalare]

edit: picture wasn't from an Alero, but I still think that if you pull the cover off the fuse box in the engine bay and look at it you'll find a relay for the radiator fan.

[chevypower91]

Hey Lucalare, thanks for the reply.

The gauge is woking fine and it' reading normal. I don't know if it would be a relay, I believe that the relay receives the signal to turn the fan on/off from the ecm (which it receives it from the coolatant temp. sensor)?

[clutch1]

It's a super weird circuit, IIRC... but I'm too lazy to look right now, they can be found here

http://www.aleromod.com/forums/showthread.php?t=19347&highlight=bcm+wiring

[Lucalare]

I would try the relay thing anyway. I think the way this circuit works is: the relay has a power and ground post, plus a signal post from the ECM to tell it when to let power flow. If the relay fails though, it might make the power and ground connection constant, hence the fans are always running(or maybe running whenever the ignition is on, in which case there's a remote wire thrown in there somewhere too.) If this is the case, putting in a functional relay should fix the issue, but use one from another circuit that you know works, rather than going out to buy one.

Also since the temp gauge is reading right I'd say there's nothing wrong with your water temperature sensor.

[clutch1]

^^ that's oversimplified.. it's not that easy, sorry.

Ok, there's 3 relays in the circuit. One to turn on each fan, and one to select high or low speed. The strange part is the "mode relay" that decides whether they're wired in series or parallel.. thus running on 6 volts or 12.

Which fans are turned on constantly? Both I'd assume? And then what voltage is across the motors WITH them plugged in?

It is true, though, that the PCM controls these relays. If the temp gauge is working properly, then ECT is working properly.

Answer those questions I gave you and I can help track down just what issue is happening to you.

[chevypower91]

Hi Clutch, yes both fans are running and the temp gauge seems to be working fine. I don't know the voltage- that you asked. Where is th cts located and do you have pic of it's location?
Thanks for your help!

[clutch1]

You have to go to the connectors that plug into the fans.. one multimeter lead backprobes one wire, and the other lead backprobes the other wire. Set it to DC volts and see what ya got.

[irondiezl3]

Anyone know where the coolant temp sensor on the 3400 is?

[clutch1]

On the forward facing side of the LIM, kinda below the throttle body area. It's buried pretty deep in there!

[BlueLego]

the coolant temperature sensor is on the left hand side (as if you were in driver's seat) of the engine. it's located on the thermostat housing. it's kind of a bitch to get to. anything water pump/ thermostat related is way easier when the head is off the engine. i fixed all that when my timing chain tensioner failed lol

[irondiezl3]

damn mine just sh*t the bed so this is harder to change than the thermostat?

[clutch1]

Easier than the thermostat.

But then again I'd rather do headgaskets on this engine than change the fskin thermostat.

[chevypower91]

Hello,

I just wanted to provide an update on my issue with the cooling fans running constantly. Well, we hooked up the scanner to it and a code was stored. It turned out to be one of the oxygen sensors (the one under the car) which was causing the car to run lien, thus triggering the fans to stay running. We cleared the code and solved.

Thanks to those (especially clutch1) who responded to my inquiry.

[clutch1]

That's super weird!! Glad it worked though.