Power window won't go down

Would that be the single switch on the passenger door? I presume "DOWN" did not work from either the master switch on the drivers door or the single switch on the passenger door. Since it's unlikely that both switches failed together, then one must conclude that a failure of either switch could result in both not working. I would check out the switch that has not been replaced if that is the case. It seems logical to me that the switches are wired together like this to prevent a short circuit in the event that one switch was "UP" while the other was "DOWN".

Not sure what you mean by this. What other wiring harness did you change to? Once you switched it back, does "UP" still work?

Jim,i went and got a complete panel with everythin on it,plugged it in the harness from the door jam and it did the same thing as the original Remeber everything's been basically changed with the same results,and yes this is the passenger side,i'm gonna go and try swithing the master on the drivers side and i'll get back to ya,ty

Have you checked that something is not causing the arms to bind when lowering the window. On my mother-in-laws Mercury had a rivet come out on the bottom of a piece which suppoerted the arm assembly. It moved ever so slightly causing the the system to slightly jam and not come down. I went crazy going through the same method you did with your truck, till I noticed the support moving.

R> i have a 1993 Siverado.......Passenger side window:

Jim,thank you so very much,problem solved. It was the main switch proably the whole time,i just wish i'd try this group i the beginning and i would have saved alot of time and money.But thank you again

on a pass side window both the drivers and pass switched must be good. I would bet being you already replaced the pass switch its prolly the drivers that is bad (or did I get that backwards:)?