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99Mastercraft

Weird Radiator fan experience..

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2017 GMC Sierra

 

Today after pulling the boat home from the lake, I backed in.. turned the truck off, took the key out of the ignition.. got out and the radiator fan was still running... after about 1-2 minutes, it shut off.

 

no check engine light or anything... everything seems fine.

 

what gives? has anyone else experienced a fan that will run momentarily and then shut off with the key out of the ignition? 

 

Thanks

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Yeah its normal just not very common. I notice it  mostly after using tow/haul.

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 Yea this has happened to me both times I was out in Silver Lake Sand Dunes.  I end up popping the hood and restarting it and let it idle a minute or two so it can keep the coolant flowing around.

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When towing if the fans are on when I stop, I always pop the hood and let it run for a while.

On my way home from fishing pulling the boat the last several miles are steep grades. I back the boat into the garage then let it run with the hood up until my trans temp drops 10 degrees.

Shutting it off immediately can raise the fluid temps.

Try it.

Check your trans temp, shut it off.

Wait a few minutes and check the trans temp.

 

:)

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8 hours ago, 99Mastercraft said:

2017 GMC Sierra

 

Today after pulling the boat home from the lake, I backed in.. turned the truck off, took the key out of the ignition.. got out and the radiator fan was still running... after about 1-2 minutes, it shut off.

 

no check engine light or anything... everything seems fine.

 

what gives? has anyone else experienced a fan that will run momentarily and then shut off with the key out of the ignition? 

 

Thanks

This is how a temperature activated electric fan is supposed to operate. Is this truck new to you or is the tow load new?   If you just noticed this after a couple of years of ownership, then maybe it is worth a coolant system check!

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I believe there is a factory setting in the PCM that will command the fans to run for a certain amount of time after shutoff when certain conditions are met. I know there is an option even dating back to the gen 3 PCM's for this. 

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