Quote:
I'm planning to do some upgrades to my '87 d100 in the near future (HEI ignition and super-six),and I have a question. I understand that the lock-up convertor is controlled by the lean burn computer,what would I do to control the lock-up if I were to by-pass the computer? I have heard of using a toggle switch but I don't really want to do that.
I don't understand what you are looking for. It's either automatic (computer) or manual control, what other option is there? 
Actually, I think there is a company that sells a kit that works off a speed sensor to control the lock-up and OD in later transmissions. I tried to consult with them a few years back regarding the OD upgrade in my '88 truck, but there communication skills are lacking.I can tell you this. In that year, lock-up is handled hydraulically by the valve body. There should be one wire entering the case from the rear (not the neutral safety switch, this one's farther back). With this wire disconnected, the trans will no longer lock-up. I think I remember that the computer sends a current through the wire that ALLOWS THE LOCK-UP to occur. It is still regulated through the valve body. So it's not like you would have to be flipping switches constantly. Just one way if you want it to automatically lock up, and the other if you want to override lock-up, which is very helpful with a heavy load.
D/W
