99 Sierra electric fan conversion problem

[cadams02]

Finally got around to doing the e-fan conversion. Wired the the fans to pin 42 in blue connector. Did not use the pin 33 in the red connector. Turned the fans on and set the settings similar to that of an 05 that came with e-fans. The problem I'm having is when the engine is running the fans run all the time. If I have the key on engine off, the fans do not come on. Searched all over and couldn't find any real answers. Any help would be greatly appreciated.

[odom1957]

Can you draw up a diagram of how exactly you wired it? What relay terminals go to what?

[Asylumwarp]

Just did this to my 2000 with the same programs. Fans will work with the bi-directional vcm controls. Fans stay on low when engine running. Settings in tune do zero.
Asked support for help, and it lead to the same dead end all the forums seem to also.. Anyone get this to work or is a os swap in order?
I have OS 12205612 ....

[Jon S.]

The 1999 and 2000 Truck OS (and some 2001) need a “patch” for the fans to work correctly. The best course of action is to update to 2002 OS 12212156. If this OS update isn’t an option for whatever reason, swapping in a Camaro system segment will often (but not always) get the fans working correctly.

[1FastBrick]

The 1999 and 2000 Truck OS (and some 2001) need a “patch” for the fans to work correctly. The best course of action is to update to 2002 OS 12212156. If this OS update isn’t an option for whatever reason, swapping in a Camaro system segment will often (but not always) get the fans working correctly.

Jon S. , What is the patch you are referring to? Is it done by HPT support?

I have never been able to get the early OS's to work properly after enabling E fans. Even if it's the latest calibration for that vehicle. I have had to use a 2002 truck 12212156 OS to get them to function properly after enabling the fan settings.

With the old/original OS, the fans would turn on and run as soon as the key was turned to the on position.

[1992-25th]

Now is swapping to the 12212156 OS necessary to get them to work even if I plan to a 3bar COS in the near future? Trucks not running yet, but the fans work fine with the bi-directional controls, but I have a feeling I will have this same issue when I fire the truck up

[1FastBrick]

Now is swapping to the 12212156 OS necessary to get them to work even if I plan to a 3bar COS in the near future? Trucks not running yet, but the fans work fine with the bi-directional controls, but I have a feeling I will have this same issue when I fire the truck up

In my case the bidirectional control works correctly how ever they run all the time as soon as the key is on even when the engine is cold.
While using the later OS, they worked properly at the temp they were commanded on in the tune and shut off accordingly.

[1992-25th]

Ok maybe I will just have to see, when I first wired them up the low side would come on and run anytime the key was on.
I did a little bit of digging and re-wired it and now neither fan will come on unless commanded by the bi-directional controls. But truck is yet to start so I don't know how they will act when the truck warms up.

[mgwood94]

I'm having the same problem on my 2004 Silverado that I just converted to efans from a 2005. I have a 2005 Tahoe and I'm wondering if I can copy the OS from it and load it into my Silverado. still new to this. anybody have any suggestions?

[2xLS1]

You can easily program your 04 Silverado OS for E-fans. No need to change the OS. Just copy the fan settings from the 05 Tahoe and with the right fan wiring harness it will work. I have a 04 Silverado 4.8L running E-fans.

[mgwood94]

I can go into the scanner and activate the fans, but they will not work even with the 05 Tahoe tune flashed into the Silverado

[mgwood94]

ive tried every combination on the fan settings..no luck...im gonna have to pull the efans and put the mechanical fan back in or get another ECM from a 2005

[Alvin]

The 99-02's do not have provisions to turn the fans on w/ AC. there isn't a AC pressure sensor like on later trucks. We build a fan harness for these that has a mixing circuit for AC High/Low operation. Basically low and high work just like it would from the factory and depending on the setup (a jumper wire you can cut or leave connected) turning on the AC will either bump the fans to the next higher level or turn them on in the first place.

http://www.pcmofnc.com/product/1999-...version-kit-3/

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[mgwood94]

I'm working on a 2004 Silverado

[2xLS1]

Again, I added E fans on my 04 Silverado and they work fine. You are doing something wrong.

[mgwood94]

I have a friend with EFILive that is coming by today. Apparently he knows how to fix it so we will see.

[mgwood94]

so I went to the junkyard and pulled an ECM out of a 2005. returned home and swapped it out with my 2004. I flashed it and everything works perfect. Guess my box just didn't want to cooperate.

[Brettworth]

In my case the bidirectional control works correctly how ever they run all the time as soon as the key is on even when the engine is cold.
While using the later OS, they worked properly at the temp they were commanded on in the tune and shut off accordingly.

Hello,

I have an 01 Computer, that the output controls operate both fans, and when the 6.0 is running, the Fan 2 will not operate. How do I upgrade my computer OS? Do I have to pay/use more credits?

Thank you!

[gofastwclass]

Make sure you have "2 fans" selected under "System, Fans, Hardware." If that says anything else, the second fan won't work with the temperature settings on that page.

[Brettworth]

I do.