Chevy II

I am installing a 5.3 from an 04 Tahoe into a 55 Chevy Suburban. The engine came with a mechanical fan which I am changing out and running dual Spal fans. My question is can I use the CPU from the Tahoe to operate the fans or do I have to get the wiring harnesses and relays and hook the fans up separately from the engine wiring? I plan to get a new engine wiring harness, but use the CPU that I have. I'm thinking the fans could be added in with the new harness.

Griffin (radiator and fan/shroud supplier) has told me both fans need to always run at the same time. I thought I saw somewhere on this site where people were having one fan on at one temp and then the other comes on at a higher temp, or when the AC is on. Any input would be appreciated.

Thanks for the help and any ideas.

superdave84

I haven't wired up my fan yet, but I did have to have the computer retuned to turn on the fans. (I also have a 5.3 which came with a mechanical fan)

G-Body

iTrader: (4)

You just need to have that PCM reflashed to work the electric fans and set it for what temp you want them to come on.

74modified

The ECM can be programed to have two different fan outputs. The temps can be programed. You could run both fans from one output, but no matter how you do it, you still need at least one relay in the wiring. The ECM just sends low current to a relay to switch it on or off, it cant handle the power needed to run a fan. It would be less complicated to let the computer do the switching, because it already has a temp sensor in the drivers side head.