mattpete105

I recently finished the 05-06 electric fan swap on my 99 sierra. It is wired with a Nelson fan harness, and my local tuner enabled the fans in the computer.

The problem I am having, or I should say, the problem that my tuner is having... is that the fans are always on when the truck is running. They don't turn on with just the key, but when the engine is running. From EFI Live, he can manually control the fan correctly, turning it on and off... but when the computer is controlling it, nothing changes. Whether it is below or above the temperature, it is always on low.

The wiring is correct I believe, A/C off. Tried both series parallel and aux fan modes. Only way they don't run is if he disables the fans in the tune.

He also tried taking the tune from his vette, which has electric fans, and loading it into my truck. Same thing, fans come on as soon as I start the engine. I will say again though, if he manually takes control of the fans from the laptop, he can turn them off and on correctly.

Anyone seen anything similar?

Thanks

greasemykey

iTrader: (5)

I'm not sure about efi live bUT I do know mine do the same thing. Over 25 mph they turn off.

1969x11

iTrader: (38)

upgrade to an 01-02 411 operating system=problem solved. My 99 did the same thing.