System Components - TorqShift(R)6
System Components
Electrical System
This transmission is controlled by the PCM in gas engine applications or a standalone Transmission Control Module (TCM) in diesel engine applications. This transmission is controlled by 7 solenoids. To control the transmission, the PCM or TCM uses inputs from the Transmission Fluid Temperature (TFT), Transmission Range (TR), Turbine Shaft Speed (TSS) and Output Shaft Speed (OSS). The PCM or TCM also uses engine inputs from the High Speed Controller Area Network (HS-CAN) signal for gear and Torque Converter Clutch (TCC) scheduling and control.
PCM Inputs
This transmission uses 2 types of solenoids, normally low and normally high. Normally low solenoids provide hydraulic pressure proportional to supplied current. A normally low solenoid will output very low pressure with low (50 mA) or no current, while it will supply high pressure with high current (850 mA). Normally high solenoids provide pressure inversely-proportional to supplied current. Normally high solenoids provide full output of pressure with low or no current (50 mA) and very low pressure with high current (850 mA).
Normally Low Solenoids
Normally High Solenoids
Solenoid Type
Hydraulic System Schematic
Hydraulic Circuit Identification Chart
Forward (1,2,3,4) Clutch Hydraulic Circuits
To apply the forward (1,2,3,4) clutch, the manual valve must be in the NEUTRAL, DRIVE, M, 2 or 1 position to provide line pressure to the forward (1,2,3,4) clutch regulator valve through the D432 and FCPF circuits.
Shift Solenoid A (SSA) provides regulated pressure from the SF hydraulic circuit to the forward (1,2,3,4) clutch regulator and latch valves through the PC1 and PC1Z hydraulic circuits to position the valves to apply the forward (1,2,3,4) clutch. As the forward (1,2,3,4) clutch regulator valve moves, it opens the FCPF hydraulic circuit to the C1234 circuit to supply regulated line pressure to the forward (1,2,3,4) clutch cylinder. For controlled forward (1,2,3,4) clutch engagement, the forward (1,2,3,4) clutch latch valve directs the regulated line pressure from the C1234 circuit to the opposite side of the forward (1,2,3,4) clutch regulator valve through the C1234FB circuit.
The forward (1,2,3,4) clutch is applied in 1st, 2nd, 3rd and 4th gear.
Forward (1,2,3,4) Clutch Hydraulic Circuit Diagram
Direct (3,5,R) Clutch Hydraulic Circuit Diagram
To apply the direct (3,5,R) clutch, the manual valve must be in the REVERSE, DRIVE, M, 2 or 1 position to provide line pressure to the direct (3,5,R) clutch regulator valve through the R/D432 circuit.
Shift Solenoid B (SSB) provides regulated pressure from the SF hydraulic circuit to the direct (3,5,R) clutch regulator and latch valves through the PC2 and PC2Z hydraulic circuits to position the valves to apply the direct (3,5,R) clutch. As the direct (3,5,R) clutch regulator valve moves, it opens the R/D432 hydraulic circuit to the C35R circuit to supply regulated line pressure to the direct (3,5,R) clutch cylinder. For controlled direct (3,5,R) clutch engagement, the direct (3,5,R) clutch latch valve directs the regulated line pressure from the C35R circuit to the opposite side of the direct (3,5,R) clutch regulator valve through the C35RFB circuit.
The direct (3,5,R) clutch is applied in REVERSE, 3rd and 5th gear.
Direct (3,5,R) Clutch Hydraulic Circuit Diagram
Intermediate (2,6) Clutch Hydraulic Circuits
To apply the intermediate (2,6) clutch, the manual valve must be in the DRIVE, M, 2 or 1 position to provide line pressure to the intermediate (2,6) clutch regulator valve through the D432 circuit.
Shift Solenoid C (SSC) provides regulated pressure from the SF hydraulic circuit to the intermediate (2,6) clutch regulator and latch valves through the PC3 and PC3Z hydraulic circuits to position the valves to apply the intermediate (2,6) clutch. As the intermediate (2,6) clutch regulator valve moves, it opens the D432 hydraulic circuit to the CB26 circuit to supply regulated line pressure to the intermediate (2,6) clutch cylinder. For controlled intermediate (2,6) clutch engagement, the intermediate (2,6) clutch latch valve directs the regulated line pressure from the CB26 circuit to the opposite side of the intermediate (2,6) clutch regulator valve through the CB26FB circuit.
The intermediate (2,6) clutch is applied in 2nd, 6th gear.
Intermediate (2,6) Clutch Hydraulic Circuit Diagram
Overdrive (4,5,6) Clutch Hydraulic Circuits
To apply the overdrive (4,5,6) clutch, the manual valve must be in the NEUTRAL, DRIVE, M, 2 or 1 position to provide line pressure to the overdrive (4,5,6) clutch regulator valve through the NDX hydraulic circuit.
Shift Solenoid E (SSE) provides regulated pressure from the SF hydraulic circuit to the overdrive (4,5,6) clutch regulator and latch valves through the PC5 and PC5Z hydraulic circuits to position the valves to apply the overdrive (4,5,6) clutch. As the overdrive (4,5,6) clutch regulator valve moves, it opens the NDX hydraulic circuit to the C456 circuit to supply regulated line pressure to the overdrive (4,5,6) clutch cylinder. For controlled overdrive (4,5,6) clutch engagement, the overdrive (4,5,6) clutch latch valve directs the regulated line pressure from the C456 circuit to the opposite side of the overdrive (4,5,6) clutch regulator valve through the CB456FB circuit.
The overdrive (4,5,6) clutch is applied in 4th, 5th and 6th gear.
Overdrive (4,5,6) Clutch Hydraulic Circuit Diagram
Low/Reverse (1,R) Clutch Hydraulic Circuits
To apply the low/reverse (1,R) clutch, the manual valve can be in any position. Line pressure is supplied by the pump to the low/reverse (1,R) clutch regulator and latch valves through the LP circuit. The low/reverse (1,R) clutch has 2 application circuits, CBLRS (static apply) and CBLRD (dynamic apply). The static apply circuit is supplied line pressure through the low/reverse latch valve. The dynamic apply circuit is supplied regulated line pressure from the low/reverse regulator valve. For the low/reverse (1,R) clutch to apply in REVERSE, the manual valve provides line pressure to the direct (3,5,R) clutch latch valve through the R hydraulic circuit. With the direct (3,5,R) clutch latch valve in position to apply the direct (3,5,R) clutch, it opens the R hydraulic circuit to the PC4R circuit. When the low/reverse (1,R) clutch latch valve moves, it opens the LP hydraulic circuit to the CBLRS circuit for static application of the low/reverse (1,R) clutch. As the low/reverse (1,R) clutch regulator valve moves, it opens the LP hydraulic circuit to the CBLRD circuit to supply regulated line pressure for dynamic application of the low/reverse (1,R) clutch. The low/reverse (1,R) clutch latch valve directs regulated line pressure from the CBLRD hydraulic circuit to the opposite side of the low/reverse (1,R) clutch regulator valve through the CBLRFB circuit for controlled low/reverse (1,R) clutch engagement.
Low/Reverse (1,R) Clutch Hydraulic Circuit Diagram (Applied in Reverse)
For the low/reverse (1,R) clutch to apply in PARK, NEUTRAL or manual 1st gear position, the operation is basically the same as in REVERSE except the PC4R circuit is supplied from a different circuit. Shift Solenoid D (SSD) provides regulated solenoid pressure from the SF hydraulic circuit to the direct (3,5,R) clutch latch valve through the PC4Z hydraulic circuit. With the direct (3,5,R) clutch latch valve in position to release the direct (3,5,R) clutch, it opens the PC4Z hydraulic circuit to the PC4R circuit to position the low/reverse (1,R) clutch regulator and latch valves to apply the low/reverse (1,R) clutch.
Low/Reverse (1,R) Clutch Hydraulic Circuit Diagram (Applied in Park, Neutral or Manual 1st)
Torque Converter Hydraulic Circuits
When the TCC is released, the TCC charge limit valve opens the LPX hydraulic circuit to the CCL circuit through the CRLX circuit. The CCL circuit provides fluid to the torque converter. Transmission fluid exits the torque converter through the COUT circuit and circulates through the transmission cooling system.
Torque Converter Hydraulic Circuit Diagram (TCC Released)
To apply the TCC, the TCC solenoid applies regulated solenoid pressure to the TCC charge control valve and the TCC apply regulator valve to move the valves. Line pressure is supplied by the manual control valve to the TCC apply regulator valve through the NDX circuit. As the TCC apply regulator valve moves, it opens the NDX circuit to supply the CAPY circuit with regulated line pressure to apply the TCC.
Line pressure is supplied to the TCC apply regulator valve. The TCC apply regulator valve directs regulated line pressure to the TCC through the CAPY circuit to apply the TCC. CAPY also supplies regulated line pressure to the opposite side of the TCC apply regulator valve for controlled TCC engagement.
Torque Converter Hydraulic Circuit Diagram (TCC Applied)
Fail-Safe
If an electronic, hydraulic, or mechanical transmission malfunction occurs, the PCM or TCM defaults to Fail-Safe mode and turns off any current to the transmission. This leaves PARK, REVERSE, NEUTRAL and 5th gear with an unlocked TCC as the only available gears. With SSB,SSE and the LPC solenoid being normally high solenoids, 5th gear with full line pressure is achieved hydraulically when current is removed from the transmission.
Mechanical System
Planetary Gearsets
This transmission has 2 planetary gearsets (front and rear) to provide operation in reverse and 6 forward speeds.
The front planetary gearset is a single planetary gearset and has the following components:
- Front planetary No. 1 sun gear
- Front planetary carrier
- Front planetary ring gear (part of the input shaft assembly)
The input shaft rotates the front ring gear as a driving member. The front sun gear is connected to the fluid pump and is held stationary. The front ring gear rotates the front planetary carrier assembly with a reduction ratio of 1.52:1
The front planetary carrier assembly is the only output member of the front planetary gearset in reverse, 1st gear, 2nd gear and 3rd gear. The front planetary gearset provides a 1.52:1 gear reduction ratio to the rear planetary gearset.
In 4th gear and 5th gear, both the input shaft and front planetary carrier assembly are output members of the front planetary gearset. The front planetary gearset provides both a 1:1 and 1.52:1 gear ratios to different members of the rear planetary gearset.
In 6th gear, the input shaft is the only output member of the front planetary gearset. The input shaft provides a 1:1 gear ratio to the rear planetary gearset.
The rear planetary gearset is a ravigneaux planetary gearset and has the following components:
- Rear planetary No. 2 sun gear
- Rear planetary No. 3 sun gear
- Rear planetary carrier assembly (2 sets of pinion gears)
- Rear planetary ring gear assembly
Powerflow through the rear planetary gearset is as follows:
- In reverse, rear sun gear No. 2 is driven, the rear planetary carrier is held and the ring gear is the output at an overall transmission reduction gear ratio of 3.128:1
- In 1st gear, sun gear No. 3 is driven, the rear planetary carrier is held and the ring gear is the output at an overall transmission reduction gear ratio of 3.974:1
- In 2nd gear, sun gear No. 3 is driven, sun gear No. 2 is held and the ring gear is the output at an overall transmission reduction gear ratio of 2.318:1
- In 3rd gear, sun gear No. 3 and sun gear No. 2 are driven and the ring gear is the output at an overall transmission reduction gear ratio of 1.516:1
- In 4th gear, sun gear No. 3 and the rear planetary carrier are driven and the ring gear is the output at an overall transmission reduction gear ratio of 1.149:1
- In 5th gear, sun gear No. 2 and the rear planetary carrier are driven and the ring gear is the output at an overall transmission overdrive gear ratio of 0.858:1
- In 6th gear, the rear planetary carrier is driven, sun gear No. 2 is held and the ring gear is the output at an overall transmission overdrive gear ratio of 0.674:1
Forward (1,2,3,4) Clutch
The forward (1,2,3,4) clutch connects the front planetary carrier to the rear No. 3 sun gear. The forward (1,2,3,4) clutch is applied in 1st, 2nd, 3rd and 4th gears.
Direct (3,5,R) Clutch
The direct (3,5,R) clutch connects the front planetary carrier to the rear No. 2 sun gear. The direct (3,5,R) clutch is applied in reverse, 3rd and 5th gears.
Intermediate (2,6) Clutch
The intermediate (2,6) clutch is located in the center support and holds the rear planetary No. 2 sun gear stationary to the transmission case. The intermediate (2,6) clutch is applied in 2nd and 6th gears.
Low/Reverse (1,R) Clutch and Low One-Way Clutch (OWC)
The low/reverse (1,R) clutch holds the rear planetary carrier stationary to the transmission case. The low/reverse (1,R) clutch is applied in PARK, REVERSE, NEUTRAL, manual 1st gear and DRIVE 1st gear, below 8 kph (5 mph). The low OWC is a brake clutch that also holds the rear planetary carrier in one direction and allows it to freewheel in the opposite direction eliminating engine braking in 1st gear when the transmission is in drive. The low OWC is also a pressure plate for the low/reverse (1,R) clutch.
Overdrive (4,5,6) Clutch
The overdrive (4,5,6) clutch connects the input shaft with the rear planetary carrier and is applied in 4th, 5th and 6th gears.
External Sealing
The pump housing has a cassette-type seal for the torque converter impeller hub that is pressed into the pump and bonds itself to the torque converter hub surface during operation. The pump assembly uses a large rubber seal that seals the pump housing to the transmission case. The pump body uses a rubber seal that seals the pump body to the pump housing.
The manual control shaft has a lip seal that is pressed in the transmission case.
The transmission fluid pan and the Power Take-Off (PTO) cover use a reusable gasket.
The Four-Wheel Drive (4WD) and Rear Wheel Drive (RWD) fixed flange applications use a lip-type seal that seals the transmission case to the output shaft nut. There are also 2 plugs in the back of the transmission case that have a seal that is part of the plug.
The RWD slip yoke application uses an O-ring seal that seals the extension housing to the transmission case and a lip-type seal that seals the extension housing to the driveshaft.
On the left side of the transmission case, there is a line pressure tap plug with a seal that is part of the plug.
The large transmission case housing plug provides access to the park pawl shaft and has an O-ring seal.
The internal wiring harness bulkhead connector has an O-ring seal for the transmission case bore.
The transmission fluid filler tube uses an O-ring seal.
The transmission fluid cooler tubes use 4 O-ring seals to seal the tubes to the transmission case.
The transmission fluid drain plug has a bonded rubber seal.
