Quick test for engine fans

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  #11  
Old 09-23-2011, 10:19 PM
JGuy07's Avatar
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Why would you jump them from the relay box instead of just testing the relays themselves? My fans had problems when I first got my car; put power directly to fan motors to test those, then moved on to testing the relays and fuses which were the problem.
 
  #12  
Old 09-23-2011, 10:35 PM
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By pulling the ECT plug, you caused the PCM to set a code, and turn on the fans to protect the engine. This means that all circuitry, including relays and fan motors are good. You still need to jumper the leads from the ECT to the PCM with a resistor, to see if the PCM reacts to the high temp signal.
 
  #13  
Old 09-23-2011, 11:13 PM
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Originally Posted by JGuy07
Why would you jump them from the relay box instead of just testing the relays themselves? My fans had problems when I first got my car; put power directly to fan motors to test those, then moved on to testing the relays and fuses which were the problem.
I thought I mentioned testing the fan motors.. must've forgotten to type that part.. fuses are ok, don't know how to test relays.. care to help?

Originally Posted by z28pete
By pulling the ECT plug, you caused the PCM to set a code, and turn on the fans to protect the engine. This means that all circuitry, including relays and fan motors are good. You still need to jumper the leads from the ECT to the PCM with a resistor, to see if the PCM reacts to the high temp signal.
You mean ground one of the ECT wires? It's been done, the temp gauge sky rockets to 260 degrees and above in a blink of an eye. Ok, so maybe you can enlighten me.. IF everything is good (circuitry, relays, fuses, and fan motors) why do I only find a ground on the A/C fan (DS side fan is A/C fan if I'm not mistaken?) and nothing else on the rest of the wires (2 wires from the other fan and no power from the A/C fan)?

thanks for chiming in and lending a helping hand btw, I'm already starting to like this place.
 
  #14  
Old 09-24-2011, 12:46 AM
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Not a good idea to short any sensor wires to ground as this is a good way to damage the PCM. The instruction state you must attach a proper size resistor between the two wire going from the ECT to the PCM. The PCM uses isolated ground circuits, which are separate from the engine ground.
Since both fans went on, it means that all circuitry between the PCM and the fans is good, so there is no need to test anything from the PCM to the fans. The problem lies between the ECT and the PCM. I hope you realize that the fans are programmed to come on between 220 and 230 degrees, and you are not shooting a balloon.
 

Last edited by z28pete; 09-24-2011 at 01:00 AM.
  #15  
Old 09-24-2011, 02:10 AM
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I got that grounding skit from the service manual, it clearly stated to ground(something to that manner) the wire. Either way, I probably won't be doing that anymore haha. Yes, I've read about that, where exactly does the needle stop before the fans are suppose to kick in? between 1/2 and 3/4 of the way up there? or passing 3/4 of the way?

Also, what is there to check other than the wiring between the ECT and the PCM? Where is the PCM located by the way?
 
  #16  
Old 09-24-2011, 10:30 AM
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The connectors are common failure points, as are shorted, skinned, or pinched wires.
 
  #17  
Old 09-24-2011, 02:53 PM
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Where is the PCM located?
 
  #18  
Old 09-24-2011, 04:32 PM
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Inside the engine compartment, by the passenger side frnder.
 
  #19  
Old 09-24-2011, 07:37 PM
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Success! It turns out the damn temp gauge was giving a false temp reading! Thank god for having a personal scanner.. *phew* thanks for the help guys, hopefully this will help people in the future.
 
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