RobertV

I have a 2001 Camaro SS and the cooling fan comes on when the ignition is off and the engine temp is cold. It runs constantly until I turn the ignition on and then it stops. If I don't catch it, my battery runs down. The only thing I can think of is that the ECM is bad. Other than that, there is something else that is running down the battery and causing the ECM to have a low voltage which in turn is making the ECM think that the temp is high therefore causing the cooling fan to come on. HELP!!!

LS6427

iTrader: (2)

You may need a new "Coolant Temperature Sensor". If its on its way out, it will read improperly..........and NO, it will not necessarily show that wrong reading on the temp gauge in the gauge cluster.

When the fan runs like you say it does.....is it one fan or BOTH fans?

Because with a properly running fan system.......BOTH fans always go "on" and "off" together as well as operate in both high/low settings together. So if you have just one fan coming on and not both when temps are definitely cold.....there's something else going on.....

You could pop the two pin row covers off the top of the PCM.....just loosen one bolt per cover and then wiggle the tops off till they pop off......check the pin rows in the covers to see if any of them are burnt or discolored. Then take a look at all the pin rows themselves on the PCM for burnt pins or discoloration.

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AmDWs6

could it be a messed up direct connection ?

lt1pwr1

iTrader: (1)

My initial assumption was a bad fan relay but I don't think you would get power there unless the ignition is on....unless one side is hot with the ignition off then maybe the relay is stuck.

You could try swapping with A/C or something to test.

RobertV

I replaced the temp sensor about a month ago because of the same problem. It seemed to fix the problem until a few days ago when it resurfaced. I also might mention that my traction control doesn't work either, but I considered that a good thing. I'll check the PCM pins and also check for any bleed through voltage at the relay with the ignition off. It's very puzzling.

LS6427

iTrader: (2)

Hmmmm. The temp sensor runs the show, via the PCM just to tell the fans when to turn on and off. Check the wiring that connects the temp sensor to the PCM.......which is gonna be a BITCH and a half.

Next time the fans come on when its cold....grab the bundle of wires coming right out of the PCM ( wiring harness) and move it back and forth and side to side.....see if the fans go off and on.

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RobertV

I didn't get a chance to look at it this weekend but did pull the fuse for the fans. When I get a chance, I thought I would check the resistance at the temp sensor and start tracing it back from there. I will let you know when I get that done and, hopefully, I will find something. It wouldn't be the first time a new sensor went bad. Thank you all for your input. I really appreciate it.