I'm not removing the ecu/ecm but I won't be using wiring for the cc carb and dist. etc. when doing a performance build. Will I have lock up probs? If I don't do the converter switch is overdrive usable at all ? Did a search ,but could not find the info..thanks

we need more info. what year car?(biggest nessecity) which engine?(LG4/L69)

oops! Car is a 1986 trans am lg4

Yes, the ECM won't be able to control the TCC lock-up and you'll need to provide another means for it.

okay, but will I have overdrive at all ..locked or not? That's what I'm uncertain about.

You'll have overdrive. The ECM doesn't have any control over any of the shifting functions of the transmission, just the TCC lock-up.

Is there a measurable amount of mpg loss?

It'll depend on a number of factors. More important than the MPG loss though is the increase in transmission fluid heat you'll have when cruising unlocked in overdrive, especially if you cruise below the stall speed of the converter.

I recently added a summit trans cooler ..maybe a plus now?

It's a good idea, but having a working TCC as well would be even better.

Apeiron, Guess I'll do that mod when the time comes ..thanks for all the info help

Your car is what mine was originally. A 86 TA 700R4 LG4. Though you are not removing the ECM, the post and pic on the other thread I put up would work. At the Tranny Plug the wires are Purple which is 12V Ignition and comes from the brake switch. The power to that brake switch is via a Pink/Black wire and gets power at the fuse panel (Gagues 10Amp Fuse). The next wire at the tranny is Lt.Blue and is the signal going TO the ECM from the valve bodies 4th gear switch. That pressure switch is NormallyClosed and Opens when in 4th gear. The ECM reads that and other peramiters. The result is a ground signal back to the tranny through the Tan/Black wire. This wire is also split over to the ALDL connector and can be manually grounded there to lock up the TCC. There are Hydaulic Lockup Kits availible as an alternative to my method or the aftermarket 'KIT' to do the same thing. But the 4th switch that resides in there now (NormallyClosed) needs to be changed out for a NormallyOpen one. The one im there should have a white band around the pressure switch housing and the one you need is black. The black ones are used on the TCC port usually