Mechanics

CHEVY OVERHEATING

2002 Chevrolet Venture • 13,400 miles

Working on a overheating 2002 chevy venture 3400. Cooling fans do not come on. Fuses are good and the fan motors themselves are in working condition. Also the fan relay does not seem to be getting ground from computer. What can I try to further troubleshoot this problem? Thanks
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J.stieg
April 25, 2011.




Try checking the coolant temperature sensor, if it checks out could be a wiring or computer problem


Tiny
Rasmataz
Apr 25, 2011.
Any applicable trouble codes? Temp wise in degrees F, what is the temp reading? What about the coolant temp sensor? Did you use a voltage tester at the fan relay?


JDL
Apr 25, 2011.
I don't believe there is anything wrong with the system. You are expecting it to come on before it is really supposed to. Low speed doesn't come on until 223 degrees and high speed at 230.


Wrenchtech
Apr 25, 2011.
Yes, I checked voltage at the fan relay. All relays have +supply to them. I found out that the cooling fan relay 1 is clicking relay, but fan is not coming on, that would indicate the temp sensor and computer is working. I need more wiring diagrams. Thanks


Tiny
J.stieg
Apr 25, 2011.
See if this is more complete.


Wrenchtech
Apr 25, 2011.
I can't get the whole diagram in one picture and make it readable.
To fan number one, gray wire is voltage, white wire is ground. You see the center relay, when that relay is not energized, the ground goes through that relay. See the blue wire, that goes through the second fan motor to chassis ground.


JDL
Apr 25, 2011.
My post shows the complete diagram


Wrenchtech
Apr 25, 2011.
I have it working now and automatically responding. I found two things (not very common) that was keeping it from working. First I saw there was no ground at right cooling fan black wire. I think there should be ground there all the time. Second I found that there was a bad relay at cooling fan relay 1, bad contacts. Diagrams really helped.


Tiny
J.stieg
Apr 26, 2011.
No, there shouldn't be a ground there all the time. That is the trigger wire connected to the PCM which controls the relay through that wire. There is nothing wrong with your fan. Disconnect the wire and let it run. The fan will cycle on and off without it going into the red zone. That is the way it's supposed to work.
AD


Wrenchtech
Apr 26, 2011.
I understand that the ground for the fan relay is completed by the -trigger ouput from PCM. I was talking about "5 BLK 1050" big thick black wire down by the right fan. It didn't have cotinuity to ground, so I tapped in and put a ground wire. Its responding automatically and shutting off. Just curious why that one big thick black wire was not grounded, its not like it went through a relay, I looked at the diagram. I followed that big BLK wire to the bottom of dist box and did not have cotinuety there ether.


Tiny
J.stieg
Apr 26, 2011.

AD