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My electric cooling fans do not operate and my coolant temperature gauge is intermittent

Tiny
DANIELJORDAN
  • MEMBER
  • 1990 CHEVROLET CORVETTE
  • 17,250 MILES
I have replaced the fan relay and checked the wires and can't find any faults. The first fan is currently hard wired to a toggle switch in the car.
Wednesday, August 22nd, 2012 AT 2:37 PM

8 Replies

Tiny
RACEFAN966
  • MECHANIC
  • 5,029 POSTS
Have you tested the coolent temp sensor? Do you have digital multi meter? I can help you run some tests if you up for it.
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Wednesday, August 22nd, 2012 AT 2:55 PM
Tiny
DANIELJORDAN
  • MEMBER
  • 16 POSTS
I do have a multimeter. I found out that it comes on with the A/C running, but with nothin else. I am a diesel mechanic so these systems are a little different to me but with the same basic concept.
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Wednesday, August 22nd, 2012 AT 5:17 PM
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
You are right about basic principles. Check out the wiring schematics.

Since the fans are working with A/C, that would mean either of the following:

1. Bad PCM.
2. A fault with the ECT or its circuit.
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Wednesday, August 22nd, 2012 AT 8:00 PM
Tiny
DANIELJORDAN
  • MEMBER
  • 16 POSTS
What is the ECT? Is there a way I can test the PCM or to repair it myself? I have a multimeter and pleanty of electrical repair items.
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Wednesday, August 22nd, 2012 AT 8:22 PM
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
ECT = Engine Coolant Temperature sensor. A fault with it would result in the gauge not working as well and that should be the first item on your list to check.

You can't test the PCM and as to repairs that would depend on if you are able to erify the fault in the PCM.
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Wednesday, August 22nd, 2012 AT 9:18 PM
Tiny
DANIELJORDAN
  • MEMBER
  • 16 POSTS
Ok, the wire on the ECT isn't staying completely connected like a bad ground. I need a new plug on the end of that. Could this cause my fans not to come on?
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Wednesday, August 22nd, 2012 AT 11:47 PM
Tiny
KHLOW2008
  • MECHANIC
  • 41,814 POSTS
Yes, it can cause that because the the sending circuit is sending the wrong signal to the PCM which would have no idea as to the engine temperatre condition.
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Thursday, August 23rd, 2012 AT 5:31 AM
Tiny
DANIELJORDAN
  • MEMBER
  • 16 POSTS
Ok, I'll replace the ECT and the wire and see if that fixes the problem. When should the fans come on, temperature wise.
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Thursday, August 23rd, 2012 AT 11:18 AM

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