ok i have a TPI out of a 90 SD firebired i'm puttin it in another car and the wiring is a bit jacked where does the temperature switch(for fan/passenger side of the block tie into..(white wire)....the computer pinout only shows one spot that controls the fans and i know the fans are suppose to kick on at different temperatures so i thought there would be two locations on the computer is it all based on amout of voltage sent from the computer to the relays as to turning on just one or both of the fans?

 

There's a tech article about fan control and how to modify it.

Short version: One fan is under ECM control, the other is turned on by the swtich in the pass. side head or any time you have the A/C selected. Lots of people add a manual switch to that second fan so they can also activate it manually when needed.

 

Also, the second fan has a cool fan switch built into the block, in case the primary fan fails or the ecm fails to turn the fan on, the cool fan switch acts as a backup. The switch is located below the pass. side head. It has one connector running to it.