2002 Pontiac Grand Prix GTP cooling fans not working

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wwlrak
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2002 Pontiac Grand Prix GTP cooling fans not working

Unread post by wwlrak » Fri Jun 23, 2017 7:07 am

OK i got a 2002 GTP. the cooling fans will work if i unplug them and jump directly from the battery, all fuses are good. I took a 20amp fused jumper and jumped the cooling fan 1 relay from pin 87 to pin 30 and i get a click that comes from under my air box. I believe the engine computer is there. Not sure if i jumped the relay right or not not the best with electrical issues. Any advise is much appreciated. I,m stumped and can,t afford to take to shop

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carriedi
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Location: Oregon

Re: 2002 Pontiac Grand Prix GTP cooling fans not working

Unread post by carriedi » Sat Jun 24, 2017 12:32 am

not working as in the temp gauge gets to the red and the fans are still not running? Or does it just get higher than normal and no fan yet? Does the fan come on when you turn on the ac?


your low speed fan should turn on at 223f
ac fan comes on at about 190psi

high speed fan should come on about 230f
and high ac fan at 240psi

scan for codes. scanner will also show you if there is a fan request or not.

there are three fan relays and two fuses. cool fan 1 relay has power from the cool fan 1 fuse. cool fan relay and cool fan 2 relay both get power from cool fan 2 relay. All the relays get the signal to turn on from the powertrain control module when the temp get hot enough or the AC needs it.

Is your vehicle running warm? Is it because of warmer weather or do you actually have a problem with overheating?
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1Daddio

Re: 2002 Pontiac Grand Prix GTP cooling fans not working

Unread post by 1Daddio » Sun Jul 16, 2017 8:04 am

I also have the same problem an my code comes up as broken ground? To where an what an how do I fine it to fix

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carriedi
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Re: 2002 Pontiac Grand Prix GTP cooling fans not working

Unread post by carriedi » Wed Jul 19, 2017 2:47 am

If your car is the same as the one in the diagram the ground wire for the fans and the fan relays are the same. the black wires that go to the ground connection lower left front of engine on the transaxle stud by the starter.

I have tools that plug in and bypass the relays to see if there is a good circuit for the fans to come on at the relay connection. Ir's a good way to see if everything is good on that end of the circuit. Yhen I have relay adapters that go in for the relay and the relay plugs into the adapter. Each prong on the relay is now accessible and I can see what the relay is getting or not getting. Those tools along with the scanner that tells me engine coolant temp and if the PCM is requesting the fan relay on or not ate all important tools to check the operation of the fans.

If it is just a ground problem you could always make a new ground for the circuit if there is an open in the circuit and you can't find where the break is
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Manny

Re: 2002 Pontiac Grand Prix GTP cooling fans not working

Unread post by Manny » Mon Apr 01, 2019 4:34 pm

2004 Cooling fan #1 inop. Tested relays and fan motor, all good. Remover fan relay, jumpered circuit, fan operated. Checked all grounds. Replaced fuse box assy, ops check good.

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carriedi
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Re: 2002 Pontiac Grand Prix GTP cooling fans not working

Unread post by carriedi » Fri Apr 05, 2019 9:25 pm

Okay, since you know the fan is good because you jumped it at the relay, and you know the relay is good, you need to see if the computer is sending a fan request for that fan to turn on. It could be that your computer doesn't see a reason for the fan to come on. Is your car overheating? Is your AC pressure getting too high?

a good scanner can show you if you have a fan request or not. It will show each fan and you can see when the computer wants them to turn on. If you do have a fan request and the fan isn't coming on then you look for a problem between the computer and the relay. Since you can jump the fan at the relay and it comes on, you have to see if the computer is grounding the relay circuit. You might want to verify that you have a good relay power connection. Sometimes you can get corrosion in the connections of the wiring circuit. The computer grounds the relay to close the circuit to turn on the fan. You have to check if the computer is sending out the ground signal and if the relay is getting the ground signal. Fan 1 grounds through the cool fan relay and is tied in with the fan 2 relay.

there are certain things that can throw the computer off like low coolant on the cooling system. It could have a big air pocket so you don't get an accurate temperature reading for the whole vehicle. How is your heater working?

let me know what it is you're trying to find out. Do you need the fan to come on? Is there any problem with the way the vehicle is operating? Since the fans are controlled by the computer, if they are coming on with the engine temperature, on fan may come on at around 223F. That should be around 3/4 on the temp gauge. High speed comes on at 230+F.

Is your other fan turning on? When does it come on? They make relay adapters that go in between the fuse box and the relay that will allow you to check the voltages and grounds while the relay is in and you can check and test it to see if it is operating correctly on not. That would make it much easier for you to see what is happening at the fan relay when you think the fan should be working.
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