[rfmaster]

Originally Posted by 250cows

But will my manual shift ecm work -- can I just install a c7 wire and hook it to my tan/blk wire from trans.?

C3 ECM (1227747 - you have a later service replacement p/n ECM) was designed to handle all drive train combination's. There are no ECM hardware differences between 'manual' and 'auto' ECMs. What sets them apart is the 32k EPROM chip which provides configuration tables and instructions to a microprocessor in the ECM how to handle different engine - trany combination. Different configurations stored in EPROM's are identified with GM lingo - aka broadcast code - BCC.

Before tying TCC line from transmission into ECM it is a good idea to verify the actual TCC lockup and release operation by manually enabling and disabling (i.e. pulling this line to ground). In some applications 700R4 were configured with positive logic vs. common negative logic - ECM pulls C7 low to enable TCC. For the life of me I do not know why GM did this, but it was done. As 68 TT mentioned you'll have to get a dual poll brake switch - GM 25524845. One set of contacts is normally closed (NC) this will be used with TCC wiring to provide +12 volts to the trany. When you step on the brake paddle NC switch contacts open and de-energize TCC circuit thus kicking out TC lockup. The normally open (NO) set of contacts will be used with brake light circuit in a normal fashion.

If you need a schematic - ask.



//RF