We own a 1990 Toyota 4X4 pick-up. it has a 3VZ-E V-6, and a 4 speed automatic transmission. Recently the transmission went out. We picked up a trans. from a 1990 4Runner. The I.D tag on the side of both transmissions show the same part number.
I noticed that the solenoid wire coming from the transfer case oil pan in the trucks transmission had one red wire going to the solenoid, But the transmission from the 4Runner has two wires going into this area. One red wire going to the solenoid and one blue wire. Here are a couple pictures showing these wires.
What is the item with the blue wire?? Do we need it?

 

its the temp sensor,one have it externaly the other internal.just rewired it.

 

Thanks Mandy Tuning. So, can I just utilize the red wire? Would the ECM in the truck even have the ability to read the temp sensor?

 

it should have a temp sensor at the transfercase in the RH near oil cooler lines.