Technical Bulletin # 1186 Copyright © 2008 ATRA. All Rights Reserved. JR> Page 1 of 2 Transmission: Subject: Application: Issue Date: 4T65E & 4T40/45E TCC Applying on Top of 2nd Gear and P0742 GM, Buick July, 2008 When encountering this problem, you may be dealing with a faulty TCC release pressure switch. This switch is the only pressure switch located on the Pressure Switch Manifold (PSM) on the late 4T65E and one of six switches on the 4T40/45E and early (97-03) 4T65E Pressure Switch Manifolds. The TCC release switch is a normally closed switch. Anytime lock up is disengaged, the switch will be in the open position and “TCC release” PID on your scanner will display “on” with the release oil against the switch contact. When the TCC release oil is exhausted, (Lock Up) the switch moves to the closed position as the release oil is exhausted and “TCC release” on your scanner will display “off”. It is common for a switch to fail in the closed position and trick the computer into thinking that the release oil is exhausted and that lock up is stuck on. The PCM strategy for this code is to ground the TCC solenoid which results in lock up on top of second gear and freeze the adaptive strategies. 4T65E & 4T40/45E TCC Applying on Top of Second Gear and P0742