Cooling fan on at all times

[Jared]

So I bought a used 2001 Pontiac grand prix GTP a few months ago and the cooling fans are always on.

I realize this is a common problem and also that they come on with the a.c. And defroster for some reason? But they’re on when everything is off and the engine is just started.

I also replaced the coolant temp sensor twice because the original one didn’t seem like it was going up enough and the new one shot the coolant gauge all the way up. The new one is doing the same as the first one sending it half as high as I believe it should be.

Here is my original post on grand prix forums: http://www.grandprixforums.net/threads/101041-cooling-fan-question

The only thing I can think of now is relays? But I’m really not too sure…

Thanks for the help in advance!
(And sorry for the long post)

Topic

[My Nameis]

It’s a common problem? I’m not familiar at all with pontiacs but if it’s a common problem what’s the common fix?

[Jared]

[quote=”myfavecoupe_” post=159924]It’s a common problem? I’m not familiar at all with pontiacs but if it’s a common problem what’s the common fix?[/quote]
I mean I’ve seen this topic on this forum sometimes but the common fix is usually the temp sensor but mine is something harder…

[My Nameis]

How’s the wiring and the coolant quality? Maybe it’s the fan or ecu

[Jared]

I replaced the coolant a while back and it didn’t change it. But I also replaced the harness that connects directly to the temp sensor with two I got at the jy and they didn’t change it.

Also, I plan to go deeper into the harnesses looking for damage, but I want to try relays and easier obvious things first

[dan]

Moving this to service and repair questions here, had the same issue by the way, had a code for the Coolant temperature sensor, and because the code was on as a safe measure the PCM kept the fans on…

if you have a engine light, and a code for the coolant temperature sensor, then try erasing the code and see what that does, worked for me. if not, you may need a coolant temp sensor, or something may be wrong with the wiring too it, also check your coolant levels.

[Tray]

The a/c system does indeed use the cooling fan when it’s activated. What you can try quick and easy is yank the relay for the ac compressor and see if the fans shut off. If they do then you may have a sticking relay or wiring issue on the ac circuit. The same applies for the fan circuit too. One of your fan relays maybe sticking. Go on Youtube and look up how to bench test relays. I wouldn’t condemn your pcm at this point without testing other components

[Jared]

The only code I get is that the malfunction indicator light isn’t working… I think its a burned out bulb because it doesn’t come on when you turn the key to run

But I will try pulling the relays because at this point I think that’s the problem too

[Tray]

Here’s a few things you can try also……

1. Unplug the temp sensor and test wiring harness at connector for 5v reference with key on engine off.

2. To make sure the gauge and wiring is good you can take out the temp sensor plug it back in and heat the sensor with a heat source and see if the needle changes with the temperature or if you have an obd2 scan tool you can look at the temp the computer is seeing and see if it seems relative to the temp on the dash. Most OBD2 scan tools will tell you the engine temp in the pids.

Did the fans continuously run when you purchased the car or only after you changed the temp sensor? What problem was you having to make you go after the temp sensor to begin with?

Keep us posted on what you find

[Jake F]

Check your main fuse/junction box under your hood for the no.2 fan relay. That was my culprit on my toyota. I believe you can test it by having someone turn your key to ON position while you have your finger on the relay. If your fans come on in ON position without cranking the engine, it’s gotta be a $20 relay (dealership).

Attachments:

• box.jpg

[Jared]

So I pulled one relay and It turns off one fan and the other relay turns off the other fan but both don’t turn off. Does that mean anything?

Also I fixed my other light and now I get a code about the coolant system reading low

[Jared]

And also the fans were on before I changed the temp sensor and the wire leading up to it

[Author]

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