Transmission computer maybe?
 

'98 12 valve 4x4 auto.

The truck has shifted strange since day 1. It would shift from 1st to 3rd at 5 MPH, then OD about 20. If I pulled the lever to 2nd on the column, it would shift from 1st to 2nd at 5 MPH again. So it DOES have a 2nd gear, meaning it's not lost. But when I would shift it manually from "2" to "D", the RPMs would surge anytime, except at WOT. It also did it from 3rd to OD, unless I have the converter switch in the "locked" position. Recently, I bypassed the TPS with a rheostat on the kick panel, which solved the surging problem (bad TPS).

Now, I'm about to order a new transmission, but want to make sure the 1-3 shifts aren't because of the computer, or whatever controls the shifts. So, does anyone know what exactley shifts the transmission? I realize it's electronic, but are there internal components (electrical) that could be bad? Bypassing the TPS is SUPPOSED to allow me to control the shift points. Unfortunatley, the only thing it lets me control is the speed at which OD kicks in. Not good.

I dunno bout these but

bump ............maybe someone else does?

the electric govenor and electric pressure switches in the valve body, about 200 bucks for both, easy fix, takes about an hour :c:

Is there a way to check and see if they are indeed the problem? Or is this a case where 99% of the time, they are in fact the culprit?