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HELP PO 118 Fans run constant

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Old 04-23-2010, 10:07 PM
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Default HELP PO 118 Fans run constant

Hey,

Little help please.

Have a po118 code and both fans on a 2004 GTO run the second it starts.
I assumed bad engine coolant temperature sensor. ECT.

Went to the local Chevy dealer and bought a new one. Did not solve the problem.

I have a service manual for this 2004 GTO. Its says I should read around 3520 ohms at the current temperature.

I cant read resistance from the old ect or the new one. pin to pin, or one pin to the body of the ECT.

Might add my 2004 GTO is highly modded. I have HPTuners pro. New at tuning. Could it be in the tune. Also the AC is empty right now..no ac charge..just got her running.

To the wires from the ECU. Mines a two wire connection. I get a momentary 2.6 vdc on the one pin. By momentary I mean as soon as I touch ground it reads, then immediatly goes to 0.
The other pin is to ground.

Any thoughts. I bought bad new parts but this thing is just a thermister. Not to fragile.
This is causing my car to run badly when it goes into closed loop. Also the fans run continuosly.

I have searched here. Other forums. Google. Not much on ECT's, and what there is has not helped me so far...so I post in hopes

Thanks
Blue

Last edited by blue2050; 04-23-2010 at 10:17 PM.
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Old 04-24-2010, 04:00 AM
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Originally Posted by blue2050
Hey,

Little help please.

Have a po118 code and both fans on a 2004 GTO run the second it starts.
I assumed bad engine coolant temperature sensor. ECT.

Went to the local Chevy dealer and bought a new one. Did not solve the problem.

I have a service manual for this 2004 GTO. Its says I should read around 3520 ohms at the current temperature.

I cant read resistance from the old ect or the new one. pin to pin, or one pin to the body of the ECT.

Might add my 2004 GTO is highly modded. I have HPTuners pro. New at tuning. Could it be in the tune. Also the AC is empty right now..no ac charge..just got her running.

To the wires from the ECU. Mines a two wire connection. I get a momentary 2.6 vdc on the one pin. By momentary I mean as soon as I touch ground it reads, then immediatly goes to 0.
The other pin is to ground.

Any thoughts. I bought bad new parts but this thing is just a thermister. Not to fragile.
This is causing my car to run badly when it goes into closed loop. Also the fans run continuosly.

I have searched here. Other forums. Google. Not much on ECT's, and what there is has not helped me so far...so I post in hopes

Thanks
Blue
No A/C pressure = fans on full time.
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Old 04-24-2010, 10:38 AM
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Thanks for that info. Really! I thought maybe, was it looking at system in HPT.
I could force them off buit rather err towards safe.
Get that ac vacuumed and charged Monday. Been a while hope all is well.

Now to find a new famale connector for the engine coolant sensor.

The copper wire was broken inside the insulation. Giving me the sckewed VDC readings. It was/is broken up inside the connector. Push on a pin it makes a very poor contact.

Cut it off...damaged the pins trying to getthem out.
Got 5vdc from the wire to the ECU/PCM. Check.
Other wire is ground.

Put a resistor across the wires for now if all else fails. Make it read 160 or so.
Mines got a 160 stat.

Thanks again!
Blue
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Old 04-28-2010, 06:00 PM
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Glad to see you got your answer. Thread closed.
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