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Please help!! Coolant temperature sensor problem

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Old 07-30-2012, 09:14 AM
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Default Please help!! Coolant temperature sensor problem

Alright guys, I need help figuring this out. I have a 2000 R/T and my fan clutch got to where it would stay engaged at all times when the engine is running. I checked to see if it was locked up but it turns freely when the motor is not running. I took it to autozone and they told me it was probably the CTS so they unplugged it and put an ohm meter on it and it was fine so they tested the plug with the ohm meter and they said that there was a short in the wires or a loose ground. When I got home, I went over the wire cluster and couldn't find a loose ground or anything. I later cranked it up and the fan wasn't roaring any more. The next day it started roaring again so the only thing I could think of is that there is a loose ground somewhere but I have no idea where it would be. Please let me know your thoughts on this and if it is a loose ground, where is it grounded at. Thanks for your help.
 
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Old 07-30-2012, 10:19 AM
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Your fan clutch is not electrically controlled, it's all mechanical.

You also can't just use your meter to check the circuit unless you disconnect the other end from the PCM.

The clutch fan will engage when it gets hot. If you're stuck in traffic, a/c on, you'll probably here it roaring. As you go down the highway it should stop.

It's also normal for it to "roar" at first when starting. It shouldn't last long though.

Other than the "roar" what problems do you have? How's the temp?
 
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Old 07-30-2012, 10:50 AM
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The fan clutch is constantly engaged unless the engine is off. The fan roars at all times when the engine is cold, warm, or hot. The guy at Autozone disconnected the plug from the wire and put the meter on the pins of the sensor to test it. Other than the fan being constantly engaged when the engine is on, there are no other issues. The gauge works fine nor does it over heat.
 
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Old 07-30-2012, 12:41 PM
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It sounds like the fan clutch has failed, replace it.
 
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Old 07-30-2012, 12:55 PM
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If it has failed, would you be able to turn the fan when the engine is off? From what I understand if it had failed, it would be locked up when the engine is off or on but with mine, it is only locked up when the engine is on. The clutch is also not too old either. I replaced it about 10k miles ago.
 
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Old 07-30-2012, 06:43 PM
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You should be able to spin it by hand when cold, the book says it should stop within 5 revolutions.

To test hot, there is a procedure in the book. In a nutshell.

Insert a thermometer in the shroud between the radiator and fan, drill a hole for it. If you block off the air with a piece of cardboard and start the truck. Run it at 2400 rpm and within 10 minutes the fan should start to engage, and get very loud. The air temp should be between 190 and 205. Then, remove the cardboard. When the air temp is between 135 and 175 you should hear a definite decrease in noise.

FYI, aftermarket fan clutches suck. Lots of people have problems with them.
 
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Old 07-30-2012, 11:31 PM
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Originally Posted by 00DakDan
FYI, aftermarket fan clutches suck. Lots of people have problems with them.
+1

I had the exact same problem with a fan clutch I bought at Autozone. Stayed locked up and roaring like a jet plane all the time, especially in hot weather. The Autozone manager was very good about it, gave me a full refund in cash even though the part was over 90 days old. I bought a used OEM fan cluctch off a wrecked Dakota at a junk yard, it worked fine but only lasted a year, then it went bad too. I bit the bullet and paid $120.00 for a new OEM fan clutch at the Dodge dealership in August last year. It has been working fine ever since. It does have some roaring noise to it on a cold start but that goes away after I drive about half a block down my street, which is how the clutch is supposed to work anyway. Some parts you just have to use OEM to get it to work right.

Jimmy
 



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