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Fan stays on until battery is dead


Well-known member
Nov 24, 2003
Las Vegas, NV
2017 Grand Sport 90 ZR1 57 Bel Air
My radiator fan is coming on and staying on until the battery is dead. Has happened 3 times now, not every time I drive it. Having to pull the negative cable off when I park it. Can't find any relay that is marked for the fans. Is this a PCM controlled function? If not where is the relay for the fans? Temp sensor bad? I am going nuts with this car. Of course just made the last payment and it has 68k on the clock. eSLD has something wrong now also. I was thinking about a .45 slug to radiator but my wife said that wouldn't be the best solution but I have my doubts. I know it would make ME feel better. Any help is greatly appreciated.
I hope this answers your question.

"The engine cooling fan system is composed of one electric cooling fan and a cooling fan control module. The engine control module (ECM) controls the fan speed by sending a pulse width modulated (PWM) signal to the cooling fan control module. The cooling fan control module varies the voltage drop across the cooling fan motor in relation to the pulse width modulated signal, which enables cooling fan operation at variable speeds. The ECM will only operate the cooling fan at certain percentages to prevent undesirable noise and vibration. The cooling fan control module is thermally protected to prevent module damage in the case of a short circuit condition in the cooling fan motor"

The fan is only supposed to run at most for two minutes after engine is shut off. There may be a fuse associated with the fan circuit.
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Thanks for the reply. I haven't been able to find any fuse marked fan. I hope I won't be in the market for a new ECM.
Wow. I will have to check this out. As he said in the video this is merely a power bus. My problem seems to be power when it is not needed. I thank you for the link. I wasn't aware of the power bus, so as they said at Faber College "knowledge is good" Thanks again.
An update on this problem. As soon as I post this the problem will probably return but.......all of a sudden everything works again. I went to every ground I could find and took them off and put dielectric grease on them and retightened everything. Been about 2 months without having to pull the negative off the battery. Very strange stuff. Thanks for everyone's replies. Hapy motoring.
Grounds can be the fault of electrical gremlins that seen to not have any explanation.

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