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Rad Fans Not Coming on Engine over-heats

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Old Sep 3, 2012 | 11:52 AM
  #21  
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Originally Posted by Mike1995
Obviously the pcm is turning the fans on either when the a/c is called for or when the temp sensor is disconnected. So, with those 2 tests completed and working correctly, then any mechanic would tell you that the pcm is fine.

Your next step is to either replace the thermostat or the temp sensor.
I will replace the temp sensor as far as the stat goes that would be a real horror story. Thank-you for your input I will update once I replace the sensor
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Old Sep 6, 2012 | 04:06 AM
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I do have a new temp sensor But decided not to change it. If my temp gauge works ok I have to assume my temp sensor is ok.

I did go to the local bone yard and I did find a 2003 Venture mine is a 2005. Can anyone tell me if the PCM will work from the 2003 in my 2005. The options seem to be the same on both vans.
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Old Sep 6, 2012 | 04:34 AM
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Why are you still hooked on replacing the PCM?
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Old Sep 6, 2012 | 09:55 AM
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Yes I am due to the fact that the other items such as that Stat, temp sensor, Rad Cap, do not make much sense. Also note I did have the same problem on my 99 Olds 3.8L and non of the above helped when I replaced the items.
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Old Sep 6, 2012 | 10:26 AM
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Originally Posted by rolm
Yes I am due to the fact that the other items such as that Stat, temp sensor, Rad Cap, do not make much sense. Also note I did have the same problem on my 99 Olds 3.8L and non of the above helped when I replaced the items.

Thermostat and rad cap have nothing to do with the fans not coming on, but you need to replace the temp sensor before you replace the PCM.
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Old Sep 6, 2012 | 02:25 PM
  #26  
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Well against my better judgement I did replace the temp sensor and as I thought no change. Looks like the ECU or a wire that transmits the ground from the ecu to the fan relays is shot. My guess it'* the ecu vs a wire. Before I change that ecu I will look for a 12-inch pusher fan I can install in front of the rad and have it controlled by it'* own temp and relay controller that may be the cheaper way to go. In this way I will not have to deal with re-flashing the new unit.
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Old Sep 6, 2012 | 07:19 PM
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I don't understand why your not getting the fact that the PCM controlling the fans is working. Just because it didn't work on another vehicle does not mean it won't work here. And changing to a different year PCM is REALLY not going to work either. Tool up, and change out that thermostat. Otherwise, your wasting our time by assuming and changing out parts that don't need to be changed.
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Old Sep 6, 2012 | 07:37 PM
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Why do you think it'* the stat. If I were a betting man I would give you 2 to 1 odds.

Is there anyone out there that has a temp and relay controller I can buy at a reasonable price. I can buy a 12-inch fan for $30 or so and that will solve my problem.

I will bet you 50% of warped heads and blown intake gaskets is due to a gm flaw in their cooling systems.
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Old Sep 6, 2012 | 07:49 PM
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1. A 12 inch fan is NOT going to keep your engine cool.

2. 50% of warped heads is due to engines overheating because the driver NEVER pays attention to the gauges. Ask any wife.

3. Based on no repair history with your current vehicle, I bet you 10 to 1 odds that your t-stat is not opening like it should.
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Old Sep 8, 2012 | 12:41 PM
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Ok I fixed the fans at least to my satisfaction. I placed a ground on relay 1 where the ecu should be sending the ground and the fans work in low speed. I also installed a kill switch for the winter no need to run the fans especially when the heater is on. This fix does not cause any error codes. This seems the best fix I can come up with. I may consider an ECU swap if I want to go to that expense. later
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