It's very typical for my FAL efans to run for a 10 or 15 seconds after I shut off the truck. Yesterday, I found them still running about 15 minutes later! I started the truck and idled it for a minute, then shut it off. The fans didn't come on this time. Any thoughts?

 

Yes it is normal for the fans to run up to a minute after you turn the truck off to cool the system. But the 15 minutes is no and you have a problem. I think this is addressed in the instructions trouble shooting page.

 

Is your ignition trigger line on a constant on voltage supply?

It may think that the truck is still running. My FAL instructions said that it does have the possibility of the fans kicking on up to 15 or 30 secs after shut off. If the controller still thinks the truck is running if it was set on a constant line, it may run until the temp sensor falls below its threshold.