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5.7L Primary coolant fan inoperative, ecm is the problem

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Old 05-17-2011, 07:22 PM
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5.7L Primary coolant fan inoperative, ecm is the problem

Well my original post was a load of bogus diagnostics since I confused the primary fan with the auxillary fan. Today, armed with a Tech 1, and a clear head, I found my problem. This car operates as it should, and btw, the stock temp gauge read right on the money, according to the tech 1. Its a little difficult to follow since it is not a linear gauge. 100-260, 220 being the halfway mark makes it a little difficult. However when the Tech 1 said coolant temp was 220, the gauge was right in the middle, exactly on 220 from the drivers view. I drove around(very hard driving) until the coolant temp was 233, and at that point I pulled over and popped the hood, both fans were on. I continued driving, now easier driving on the car, and it remained in the 220-230 range.

Prior to this drive I also found the fan switch located just above the starter, and grounded that out. The fan kicked on as if the car were overheated.

I understand the reasons why manufacturers like to keep their vehicles at aprox 180-210 degrees, but I have never seen a car meant to be allowed to get in the 230 degree range. I wonder if it was done to help pass emissions? Unless someone knows something I dont..(and thankfully Henryd3, and Reid Fleming do), I decided to go ahead and order a hypertech 200 degrees on, 185 degrees off, fan switch. 230 is just too hot for my taste.

Last edited by Dark Ember; 05-18-2011 at 09:55 PM.
Old 05-17-2011, 07:38 PM
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Re: 5.7L Primary coolant fan inoperative, ecm is the problem

The sender you disconnected is not the one that tells the computer what the temp is, it only makes the temp gauge work. The CTS or coolant temp sensor on the front of the intake with two wires, I believe black and yellow, going to the connector that plugs into it is the one that does that. Replace the CTS FIRST
This is of course assuming that the wiring and connection to the CTS is not the problem

Last edited by henryd3; 05-17-2011 at 07:52 PM.
Old 05-17-2011, 08:17 PM
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Re: 5.7L Primary coolant fan inoperative, ecm is the problem

Yea, you are right. I was just lookin through my shop manual and found a component locator that said the auxillary coolant fan switch was on the right hand side of the engine(passenger), and the coolant fan switch was on the lower right hand side of the engine. I also noticed that one of the wires going to the auxillary relay is positive when it should be the ground.

I think I spent wayy to much time in the sun today, I'm at that point where I need to walk away from it and hit it again on a fresh mind. Thanks for then input. Look for updates to this thread.
Old 05-17-2011, 08:19 PM
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Re: 5.7L Primary coolant fan inoperative, ecm is the problem

You have your fans reversed. The primary is the driver side. The secondary fan is the passenger side. See my sig.
Old 05-17-2011, 08:22 PM
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Re: 5.7L Primary coolant fan inoperative, ecm is the problem

Originally Posted by Reid Fleming
You have your fans reversed. The primary is the driver side. The secondary fan is the passenger side. See my sig.
That would explain why the grey wire in the auxillary circuit, which should be ground, but instead is shorted to power. That would cause a fan to not work. Don't ask me what was up with the fan temporialy kicking on those few times though. I'm going to look into your sig link now.
Old 05-18-2011, 09:47 PM
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Re: 5.7L Primary coolant fan inoperative, ecm is the problem

updated. Thanks again guys. Im a little embarassed that I let this car kick my butt so badly, but with your help I got my head on straight and got it sorted. Still not sure what it was that got me thinking the auxilary fan was the driver side....
Old 05-19-2011, 07:55 AM
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Re: 5.7L Primary coolant fan inoperative, ecm is the problem

Where did you go to get the "hypertech 200 degrees on, 185 degrees off, fan switch. 230" ???? Thanks

Stone
Old 05-19-2011, 10:49 AM
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Re: 5.7L Primary coolant fan inoperative, ecm is the problem

Here's one source
http://www.summitracing.com/parts/HYP-4028/
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