Author Topic: electrical ?  (Read 2191 times)

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Offline Jerry

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electrical ?
« on: January 06, 2013, 03:32:04 PM »
I am tring to chase down why my fan does not come on. I believe my temp sensor is bad. Why do i think this. I checked the resistance (i think i did it right help me out here). I set the ohm meter to 2000 touched the to leads to the two prongs on the sensor and got a reading of 1270, the wiring dia says that the nominal res should be 2.5 at 20 degres celius which is 68 degree f +or- 6%. Sounds like it is bad to me. I am not sure if the meter is set correct or if i need to remove the sensor from the block to test it?  I believe the senor is the issue because i am not getting any power thur any wire that is suppose to turn the fan on, i know that fan works and i know the fuse is good.   Any thoughts would be great i know very little about electric.  I never had the orginal system working because the temp sensor that was there was a spall  and when it grounded out the fan would work, the problem with that system was that it kept the engine from reving past 4700 rpm.

Offline Lance-W

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Re: electrical ?
« Reply #1 on: January 06, 2013, 03:40:48 PM »
The sensor has 2 wires or 1? 

If 2 just take the connector off and on the connector put a small piece of wire and jump the terminals.  If it's the sensor that keeping the fan from working than when you jump the terminals it will come on.

If it only has 1 wire going to it you just simply ground out that wire to the frame or something and the fan once again will turn on if it's a bad sensor.

Offline Jerry

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Re: electrical ?
« Reply #2 on: January 06, 2013, 04:01:57 PM »
The system is 2 wires.  Itried that and got nothing.  In checking the sytem with a test light i got nothing to light up. It looks like there is no power coming from the computer to tell the load controller to power the fan. I thought the sensor was bad which in turn would not let anything down the line work

Offline Yummi

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Re: electrical ?
« Reply #3 on: January 06, 2013, 05:22:57 PM »
My understanding of most ECM's is that they fire / trigger a ground to close the loop.  If you are looking for power you maybe checking two grounds? 
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Offline Lance-W

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Re: electrical ?
« Reply #4 on: January 06, 2013, 05:33:19 PM »
If your checking for power at the fan you have to have that little jumper in the connector at the sensor or the ECU won't send any power to the fan cause it's gonna figure it not hot enough to need the fan.  If it thinks it needs to turn on the fan the ECU sends power to a relay that controls the amount of power that the fan would draw.

Offline Jerry

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Re: electrical ?
« Reply #5 on: January 06, 2013, 07:04:35 PM »
I am going to have to go back and make sure all the grounds are connected. The jump wire did nothing. If i can not get it working thur the ecu. I am going to put the old spall sensor in about 9inchs from the sensor.

Offline Dunebound69

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Re: electrical ?
« Reply #6 on: January 07, 2013, 09:39:57 PM »
My ecm switches to ground. I lost a motor to this problem. I had the ecm calling for the fan. It was hit and miss. I now can turn it on manually, ecm, and a thermal switch another backup. Plus a indicator light that the computer wants the fan. Another indicator light that the fan is on! Tired of killing motors.

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