Fan problem. Fans come on and stay on when I start the engine. Even with AC off. [Solved?]

[16RRGT]

Pretty much self explanatory. A couple seconds after the engine starts, the fans come on and stay on until the engines turned off. Even when the engine is cold.

2016 5.0 Roush 2.3 dealer installed, Roush tune, no changes in tune or any other modification.

What should I be checking?

UPDATE: Weeelllll.... it stopped. On it's own. I have no idea why it started and no idea why it stopped.

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[Dave2013M3]

Oh shit!!

J/K probably just a stuck switch. Any codes?

 

[RPDBlueMoon]

Have you checked pulling a fuse?

 

[K4fxd]

Is your A/C on?

 

[16RRGT]

Is your A/C on?

Nope. Off or on, stays the same.

 

[16RRGT]

Have you checked pulling a fuse?

Nope. So, does pulling a fuse reset it somehow?

 

[16RRGT]

Oh shit!!

J/K probably just a stuck switch. Any codes?

Nothing. Other than being an annoyance, there's no problem except it's likely to increase the time the engine needs to warm up.

 

[Arknsawchuck]

If I got this right the fans should kick on when the engine has hit a preset temp. So it seems something is telling the fans the engine has hit that temp. Thats my best armchair guess. Id start looking for a sensor or switch in that system.

 

[WildHorse]

What should I be checking?

The connection to the fan to see if it overheated, melted the connector and shorting.

 

[bauern]

Connect a scan tool/code reader to it and see what temp the sensors are telling the PCM.

 

[16RRGT]

Connect a scan tool/code reader to it and see what temp the sensors are telling the PCM.

I did that today. Nothing shows.

 

[16RRGT]

OK. No codes. So. I'm going to start with the coolant temp sensor.

If I can find it. So far, no joy. Any ideas?

 

[bauern]

I did that today. Nothing shows.

OK. No codes. So. I'm going to start with the coolant temp sensor.

If I can find it. So far, no joy. Any ideas?

Sorry didn't mean check for codes. You need to see the live data. Does your scanner provide live data?

 

[K4fxd]

Good luck finding a coolant sensor........

There is none, the PCM infers if from the cylinder head sensor. It will usually run 10 degrees cooler then the CHT dash display.

You need a live scanner.

 

[Super-Genius]

This probably won't help, but I had my GMC truck do the exact same thing. The vehicle wasn't getting hot either. Turns out it was the thermostat. I thought that was really weird, but hey, it's fixed, and hasn't done it again.

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