GM Service Manual Online
For 1990-2009 cars only

If electrical power is interrupted with the transmission in third range, shift solenoid C and torque converter clutch pulse width modulated (TCC PWM) solenoid , if the TCC is applied, is de-energized. Shift valve C will move up, changing the exhaust path of the 4-5 clutch to exhaust backfill and the exhaust path of the 2nd clutch to the B trim valve. Normally closed pressure control solenoid A continues to block the exhaust of the A trim signal pressure, and the trim signal remains control main. The solenoid signal pressure on top of trim valve A produces maximum A trim pressure, which is routed through shift valve D to the 3rd, 5th, and Reverse clutch, keeping the clutch applied. With the manual selector in a forward position, main pressure continues to feed the 1-2-3-4 clutch through the E shift valve and manual valve. The combination of the 1-2-3-4 clutch and the 3rd, 5th, and Reverse clutch applied keeps the transmission in third range for limp home capability. If the TCC is applied, the TCC PWM solenoid de-energizes, causing the TCC PWM trim valve to move up, exhausting pressure from the top of the converter flow valve. The converter flow valve moves up, redirecting main overage to converter in and converter out to the cooler. The TCC is now released.

Third Range - Limp Home


Object Number: 1546388  Size: FS