Is therea way i can do some basic diags of the od units without tge car running. Ie put voltage to the solenoid. Someone cut the wires to shifter and removed actuation device.

 

There's nothing you can do not running other than pull the pan and checking for fluid condition and debris. The pump is driven by the rear wheels. If you connect 12V to the white connector next to the fill plug (fuse suggested) and take it for a ride, the OD should kick in at 5-10MPH. You can definitely feel it. If you have reverse it's a sign that the OD unit *might* be OK.

 

I put one in my 57 chevy truck.
there is a first gear lockout switch that can go bad. Test it by putting an ohm meter on the connector part and have someone put trans in first, then out of first. Do it twice to confirm.
the reason it’s there is you can destroy the overdrive in first.
so if u bypass that switch, just know that u can damage it.
what u can do is rig up a switch to energize it.
first, i used old telephone wire because it’s thin.
clip one end on the positive terminal of the battery, and in 4 inches, cut the wire and solder a 10 amp fuse to the 4” piece, and the rest of the wire to the other side of the fuse.
then find a convenient place on the console (because it’s plastic), tape it there with duct tape so it stays and u can work the switch and run the wire into the car behind the seat onto the console, cut the wire and attach both ends to the switch, then run the rest of the wire to the blade terminal on the left side of the overdrive unit.
go through first and second normally , then instead of third , disengage the clutch and flip the switch. Let out the clutch and u should be in second overdrive. Then go to third about the speed u would go in 4th, and then go for 4th. You should be st 55-50 mph.
don’t forget to turn it off when u come to a stop.
how it works normally, is the computer is programmed to engage the overdrive.
you become the computer.
so the overdrive relay engages, then sends power to first gear lockout switch.
then when u shift to second, power goes to the side terminal just above the pan.
then power goes to the internal pressure switch and when pump pressure is sufficient , the pressure switch powers the solenoid on the internal valve body, and then the servo squeezes the clutches and then the drum rotates the planetary gears, putting u in overdrive.
don’t worry about the wire, it’s thin enough the door will close normally,
Or u can just close the door and have the wire go through the window opening to the console.
you will need about 25 feet of wire