LT1-LT4 Modifications 1993-97 Gen II Small Block V8

Fans turning on with acc switch

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Old Sep 10, 2009 | 01:05 PM
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Question Fans turning on with acc switch

Recently my fans started turning on when i turn the key to the on position (engine not running). Anyone know what could be causing this?
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Old Sep 10, 2009 | 01:12 PM
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Have you changed anything? I wired mine up to do this.
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Old Sep 10, 2009 | 01:34 PM
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When does it do it.. like how long after you shut down the car..
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Old Sep 10, 2009 | 01:36 PM
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Originally Posted by the_merv
When does it do it.. like how long after you shut down the car..
I think he means when he turns the key to the ON position before he starts it.
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Old Sep 10, 2009 | 01:50 PM
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Originally Posted by 94Z28rag
I think he means when he turns the key to the ON position before he starts it.
exactly
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Old Sep 10, 2009 | 02:07 PM
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Originally Posted by 94Z28rag
Have you changed anything? I wired mine up to do this.
not really. it happened at the same time some wires got messed up under the car causing my fuel pump not too work. fixed those and the car starts up now. but the fans turn on automatically and i cant connect to my ecm using my laptop.
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Old Sep 10, 2009 | 02:37 PM
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Originally Posted by 94Z28rag
I think he means when he turns the key to the ON position before he starts it.
I figured that but I was just asking.. if the Temp Sensor temp is still above whatever they are set to come on at then they will come on when the Engine is off.
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Old Sep 10, 2009 | 03:41 PM
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Originally Posted by the_merv
I figured that but I was just asking.. if the Temp Sensor temp is still above whatever they are set to come on at then they will come on when the Engine is off.
good point. where's the sensor that reads the temperature to trigger the fans? i tried it when the car was cold and they still turned on so maybe its a bad sensor.
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Old Sep 10, 2009 | 03:48 PM
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Originally Posted by C_Rules
good point. where's the sensor that reads the temperature to trigger the fans? i tried it when the car was cold and they still turned on so maybe its a bad sensor.
The sensor is in the water pump.
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Old Sep 10, 2009 | 03:56 PM
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I doubt it's a bad Sensor..sounds like you have a PCM issue..you said that some wires got tore up, maybe it's stuck into some kind of limp mode.
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Old Sep 10, 2009 | 06:28 PM
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i drove it today for the first time after getting it back and it runs like ****. the service engine light is on and i cant connect to the pcm. i have a spare computer too and when i swap it in same thing cant connect to the pcm. its idling high running pig rich and lazy under 2.5K rpms. when you take you foot off the gas and it goes into DFCO it runs even more rich. WTF happened to this thing

not even my mechanic can connect with his scan tool. its like one day i drove it home turned it off then tried to turn it back on and it all turned to ****.

Last edited by C_Rules; Sep 11, 2009 at 02:38 PM.
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Old Sep 10, 2009 | 06:44 PM
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What wires are messed up?
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Old Sep 10, 2009 | 07:04 PM
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hate to say it, but my fans did this when i had an opti failing. goes along with it running like poo too
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Old Sep 11, 2009 | 08:24 AM
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Originally Posted by the_merv
What wires are messed up?
the damaged wires were the fuel pump relay ones inside the car.
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Old Sep 11, 2009 | 08:29 AM
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Originally Posted by itSSlowZ28
hate to say it, but my fans did this when i had an opti failing. goes along with it running like poo too
so your opti went out and your fans would automatically come on when you turned the switch into the on position? weird. i have an msd unit but its quite possible its failing. i wish my obd1 port was working so that i could connect datamaster to the car to see wtf is going on.

what else would your car do?
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Old Sep 14, 2009 | 08:41 AM
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okay anybody else got any ideas. my obd1 port is not working so i cant scan the pcm. tried swapping pcms, using a different scanner/cable, using cleaner on the ports and nothing. car still runs like crap.
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Old Sep 17, 2009 | 08:47 AM
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okay problem fixed. my computer crapped out, the computer i bought didnt work, and the third computer i bought cleared it all up.
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