I had this issue when if first did Efans..
i ended up goin with the 12212156 2002 OS and it never did it from then out.

 

Big Kid...I had actually read some of your posts but never found a resolution. Thanks for posting up!

If I apply a Custom OS in HPT will this fix the problem? Or will I have to use an 02 OS?

Thanks!

 

Unplugging 42 makes them not work.

 

ok so that means you do have a tuning issue..
Can you touch that pin to a ground and energize the fans?

 

I'll try this tomorrow and see what happens!

 

Worked perfectly when I manually grounded it.

So...I bit the bullet and bought more credits and upgraded the OS and it works perfect now. So yes, you can use the factory 05+ setup with a 99-02 and have everything function correctly.

 

this is good to know. Thanks

 

Curious which OS you upgraded to?

 

12212156 from a 2002 I found in the HPT Repository.

 

im using the 12212156 2002 OS and then updated that to the COS3 for EFI Live. its been working for years for me.

working on a 99 with Efans and trying to get them not to run when its cold and not up to temp