I'm about to swap out the 4+3 for a 700R4 in my 87 and have been going over the wiring diagrams for the auto and manual equipped cars. It looks like to me that the overdrive relay on my manual car can be deleated and the pnk/blk wire in the terminal from the fuse block can be routed to the TCC/Cruise brake switch and then back to the Grn. wire on the relay harness that runs down to the tranny. It looks like that needs to plug into the A terminal on the 700R4 which goes to the converter clutch and then from the D terminal on the trans, back up to the ECM's manual overdrive relay control wire.
In the case of the Manual ECM I'd assume that the ECM controls the grounding of that circuit to turn the OD on and off depending on throttle input.
On the Auto Trans car it looks like the same curcuit controls the converter lock up.
The first gear switch on the manual car is closed in first gear, open in all others, the same terminal on the auto cars goes to the tranny and is only open in fourth,closed in all others.
Will swapping out the Manual chip to an Auto chip change the control of these circuits? Can the Manual chip be modified to work?
Am I on the right track? Or way off base?
:smash: :confused: :smash: :confused: :smash: :confused: :cry

 

You can modify the Manual PROM, but it is easier to swap in the Auto. The shift points in the PROM control the action of the manual and auto. They just do different things. TCC vs OD, etc.

Look in the bin library for the auto version of yours,.... same rear gears, etc.

 

Thanks for you input! :D