The TV cable will force an unlock at WOT, and under low RPM/high throttle. It is comprehensive, depending on speed, gear selection, actual gear and throttle position (TV cable position). The TCC solenoid allows/disallows hydraulic pressure to engage the clutch, and the clutch actuator has a dump valve controlled by the tranny speed governor and valve body to prevent lockup under specific conditions, like the minimum speed. There are switches on the valve body that complete to ground. Both + and - are switched to control the solenoid by various inputs/conditions. There is also a forced engagement lead at pin "E" on the diagnostic test connector, which is a tan/blk wire.

I don't remember if the TCC unlocks during shifts in OEM configuration, but it stays locked with it bypassed like I have. The shifts are very firm, but it aparently has had no adverse effect on longevity in my case. I did the change over 15 years ago.


On edit:
The "no-lock" on the 'Vette may be due to not having the brake switch in the circuit. It is part of the batt. + circuit to the TCC. If the circuit is open, it will "see" the brake being applied all the time, and not lock up. I don't like the TCC to unlock (EPA thing) with brake application, compression braking is lost. This practice has been changed for the Allison, which pleases me that the TC stays locked on compression, even when braking, until the minimum speed is attained.

[ 02-15-2005, 12:37 PM: Message edited by: DmaxMaverick ]