Transmission Description - System Operation and Component Description
System Diagram
Network Message Chart
| Broadcast Message | Originating Module | Message Purpose |
|---|---|---|
| Engine Speed | PCM | Directly affects shift scheduling, TCC control, line pressure and transmission diagnostics. Indirectly affects shift pressure control. |
| Engine torque estimate | PCM | Directly affects shift pressure control, TCC control and transmission diagnostics. Indirectly affects shift scheduling and TCC scheduling. |
| APP | PCM | Directly affects shift scheduling, TCC scheduling and transmission diagnostics. Indirectly affects TCC control and shift control. |
| Commanded engine torque | PCM | Directly affects shift scheduling, TCC scheduling and transmission diagnostics. Indirectly affects shift control. |
| BPP | PCM | Directly affects shift scheduling and TCC scheduling |
System Operation
This transmission is controlled by the PCM in gas engine applications or a standalone TCM in diesel engine applications. This transmission is controlled by 7 solenoids. To control the transmission, the PCM or TCM uses inputs from the TFT, TR, TSS and OSS. The PCM or TCM also uses engine inputs from the High Speed Controller Area Network (HS-CAN) signal for gear and TCC scheduling and control.
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.
Component Description
Sensors and Switches
The PCM/ TCM controls the electronic functions of this transmission. The PCM/ TCM receives input signals from engine and transmission sensors and uses these inputs to control line pressure, shift time, TCC and shift solenoids.
Turbine Shaft Speed (TSS) Sensor
The TSS is a Hall-effect type sensor that provides a signal to the PCM/ TCM that changes in frequency as the rotating speed of the forward (1, 2, 3, 4) clutch cylinder varies.
The PCM/ TCM compares the TSS sensor signal with the engine speed information to determine the amount of slip occurring in the torque converter.
The PCM/ TCM also compares the TSS sensor signal with the OSS sensor signal to determine the gear ratio provided by the rear planetary gearset.
The PCM/ TCM uses the TSS sensor signal as an input for its strategies for shifts and TCC operation. The PCM/ TCM also uses the TSS sensor signal for transmission fault detection and diagnostics.
Output Shaft Speed (OSS) Sensor
The OSS sensor is a Hall-effect type sensor that provides a signal to the PCM/ TCM that changes in frequency as the rotating speed of the output shaft ring gear varies.
The PCM/ TCM also compares the OSS sensor signal with the TSS sensor signal to determine the gear ratio provided by the rear planetary gearset.
The PCM/ TCM uses the OSS sensor signal as an input for its strategies for shifts and TCC operation. The PCM/ TCM also uses the OSS sensor signal for transmission fault detection and diagnostics.
Transmission Fluid Temperature (TFT) Sensor
The TFT sensor is a temperature dependent resistor that is in contact with transmission fluid in the transmission sump area.
The PCM/ TCM monitors the voltage across the TFT sensor, which changes as transmission fluid temperature varies.
The PCM/ TCM uses the TFT sensor signal as an input for its strategy for shifting and TCC operation. The PCM/ TCM also uses the TFT sensor signal for transmission fault detection and diagnostics.
Transmission Range (TR) Sensor
The TR sensor has a set of Hall-effect sensors that have a pattern of ON/OFF states which are dependent on the PARK, REVERSE, NEUTRAL, DRIVE, 3,
2 or 1 position of the manual valve.
The TR sensor also provides signals for the starting system and the reverse lights.
The PCM/ TCM uses the TR sensor signal as an input for its strategy for shifting and TCC operation. The PCM/ TCM also uses the TR sensor signal for transmission fault detection and diagnostics.
Transmission 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 PTO cover use a reusable gasket.
The 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 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.
| Item | Description |
|---|---|
| 1 | Torque converter hub seal |
| 2 | Pump body seal |
| 3 | Pump housing seal |
| 4 | PTO gasket |
| 5 | Line pressure tap plug |
| 6 | Manual control shaft seal |
| 7 | Internal wiring harness bulkhead connector O-ring |
| 8 | Transmission fluid pan gasket |
| 9 | Drain plug |
| 10 | Output shaft seal (slip yoke applications) |
| 11 | Extension housing seal (slip yoke applications) |
| 12 | Output shaft seal (fixed flange applications) |
| 13 | Output shaft nut |
| 14 | Slip yoke bushing oil feed plugs (2 required, for fixed flange applications) |
| 15 | Park pawl shaft plug O-ring |
| 16 | Transmission fluid cooler tube O-rings (4 required) |
| 17 | Transmission fluid filler tube O-ring |
| 18 | Transmission vent tube |
Hydraulic System Diagram
Shift Solenoids
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 /Clutch | Type |
|---|---|
| SSA /Forward (1, 2, 3, 4) | Normally Low |
| SSB /Direct (3, 5, R) | Normally High |
| SSC /Intermediate (2, 6) | Normally Low |
| SSD /Low/reverse (1, R) | Normally Low |
| SSE /Overdrive (4, 5, 6) | Normally High |
| LPC solenoid | Normally High |
| TCC solenoid | Normally Low |
Park
Clutch Application Chart
| Gear | Forward (1, 2, 3, 4) | Direct (3, 5, R) | Intermediate (2, 6) | Low / Reverse (1, R) | Overdrive (4, 5, 6) | Low-OWC |
|---|---|---|---|---|---|---|
| Park | H | |||||
| Planetary Components | Front planetary carrier-to-No. 3 sun gear | Front carrier-to-No. 2 sun gear | No. 2 sun gear | Rear planetary carrier | Input shaft-to-rear planetary carrier | Rear planetary carrier |
H = Holding
Solenoid Operation Chart
| Selector Lever Position | Commanded Gear | SSA NL (1, 2, 3, 4) | SSB NH (3, 5, R) | SSC NL (2, 6) | SSD NL (1, R) | SSE NH (4, 5, 6) | TCC NL |
|---|---|---|---|---|---|---|---|
| P | P | Off | On | Off | On | On | Off |
NH = Normally High
NL = Normally Low
Powerflow
In the PARK position, SSD is commanded ON by the PCM/ TCM to apply the low/reverse (1, R) clutch. The low/reverse (1, R) clutch is applied to hold the rear planetary carrier. In PARK, power is not transferred from the input shaft to the rear planetary gearset. The output shaft is held stationary to the transmission case by the park pawl.
Reverse
Clutch Application Chart
| Gear | Forward (1, 2, 3, 4) | Direct (3, 5, R) | Intermediate (2, 6) | Low / Reverse (1, R) | Overdrive (4, 5, 6) | Low-OWC |
|---|---|---|---|---|---|---|
| Reverse | D | H | ||||
| Planetary Components | Front planetary carrier-to-No. 3 sun gear | Front carrier-to-No. 2 sun gear | No. 2 sun gear | Rear planetary carrier | Input shaft-to-rear planetary carrier | Rear planetary carrier |
H = Holding
D = Driving
Solenoid Operation Chart
| Selector Lever Position | Commanded Gear | SSA NL (1, 2, 3, 4) | SSB NH (3, 5, R) | SSC NL (2, 6) | SSD NL (1, R) | SSE NH (4, 5, 6) | TCC NL |
|---|---|---|---|---|---|---|---|
| R | R | Off | Off | Off | On | On | Off |
NH = Normally High
NL = Normally Low
Powerflow
In the REVERSE position, SSB is commanded OFF by the PCM/ TCM to apply the direct (3, 5, R) clutch. SSD is commanded ON by the PCM/ TCM to apply the (1, R) clutch. The low/reverse (1, R) clutch is applied to hold the rear planetary carrier and the direct (3, 5, R) clutch is applied to transfer power from the front planetary carrier to the No. 2 sun gear. With the rear carrier held stationary by the low/reverse (1, R) clutch, the input to the No. 2 sun gear causes the rear ring to rotate in the opposite direction at a 3.128 to 1 ratio, providing reverse.
Neutral
Clutch Application Chart
| Gear | Forward (1, 2, 3, 4) | Direct (3, 5, R) | Intermediate (2, 6) | Low / Reverse (1, R) | Overdrive (4, 5, 6) | Low-OWC |
|---|---|---|---|---|---|---|
| Neutral | H | |||||
| Planetary Components | Front planetary carrier-to-No. 3 sun gear | Front carrier-to-No. 2 sun gear | No. 2 sun gear | Rear planetary carrier | Input shaft-to-rear planetary carrier | Rear planetary carrier |
H = Holding
Solenoid Operation Chart
| Selector Lever Position | Commanded Gear | SSA NL (1, 2, 3, 4) | SSB NH (3, 5, R) | SSC NL (2, 6) | SSD NL (1, R) | SSE NH (4, 5, 6) | TCC NL |
|---|---|---|---|---|---|---|---|
| N | N | Off | On | Off | On | On | Off |
NH = Normally High
NL = Normally Low
Powerflow
In the NEUTRAL position, SSD is commanded ON by the PCM/ TCM to apply the low/reverse (1, R) clutch. The low/reverse (1, R) clutch is applied to hold the rear planetary carrier. Power is not transferred from the input shaft to the output shaft.
1st Gear
Clutch Application Chart
| Gear | Forward (1, 2, 3, 4) | Direct (3, 5, R) | Intermediate (2, 6) | Low / Reverse (1, R) | Overdrive (4, 5, 6) | Low-OWC | |||
|---|---|---|---|---|---|---|---|---|---|
| 1st Gear D | D | H (1) | H | ||||||
| Planetary Components | Front planetary carrier-to-No. 3 sun gear | Front carrier-to-No. 2 sun gear | No. 2 sun gear | Rear planetary carrier | Input shaft-to-rear planetary carrier | Rear planetary carrier | |||
|
|||||||||
D = Driving
H = Holding
Solenoid Operation Chart
| Selector Lever Position | Commanded Gear | SSA NL (1, 2, 3, 4) | SSB NH (3, 5, R) | SSC NL (2, 6) | SSD NL (1, R) | SSE NH (4, 5, 6) | TCC NL | ||
|---|---|---|---|---|---|---|---|---|---|
| D | 1 | On | On | Off | On | On | On/Off (1) | ||
|
|||||||||
NH = Normally High
NL = Normally Low
Powerflow
In 1st gear, SSA is commanded ON by the PCM/ TCM to apply the forward (1, 2, 3, 4) clutch. In manual 1st gear, SSD is commanded ON by the PCM/ TCM to apply the low/reverse (1, R) clutch. In 1st gear, the forward (1, 2, 3, 4) clutch connects the front carrier to the No. 3 sun gear. With the rear carrier held stationary by the low One-Way Clutch (OWC) clutch, power is transferred from the No. 3 sun gear through the rear planetary gears to the ring gear/output shaft at a 3.974 to 1 ratio. Because the One-Way Clutch (OWC) is the holding element, there is no engine braking. The low/reverse (1, R) clutch is applied in manual 1st gear to provide engine braking.
2nd Gear
Clutch Application Chart
| Gear | Forward (1, 2, 3, 4) | Direct (3, 5, R) | Intermediate (2, 6) | Low / Reverse (1, R) | Overdrive (4, 5, 6) | Low-OWC |
|---|---|---|---|---|---|---|
| 2nd Gear D | D | H | ||||
| Planetary Components | Front planetary carrier-to-No. 3 sun gear | Front carrier-to-No. 2 sun gear | No. 2 sun gear | Rear planetary carrier | Input shaft-to-rear planetary carrier | Rear planetary carrier |
D = Driving
H = Holding
Solenoid Operation Chart
| Selector Lever Position | Commanded Gear | SSA NL (1, 2, 3, 4) | SSB NH (3, 5, R) | SSC NL (2, 6) | SSD NL (1, R) | SSE NH (4, 5, 6) | TCC NL | ||
|---|---|---|---|---|---|---|---|---|---|
| D | 2 | On | On | On | Off | On | On/Off (1) | ||
|
|||||||||
NH = Normally High
NL = Normally Low
Powerflow
In 2nd gear, SSA is commanded ON by the PCM/ TCM to apply the forward (1, 2, 3, 4) clutch. SSC is commanded ON to apply the intermediate (2, 6) clutch. The forward (1, 2, 3, 4) clutch connects the front carrier to the No. 3 sun gear. The intermediate (2, 6) clutch is applied to hold the No. 2 sun gear, transferring power through the rear planetary carrier to the rear ring gear/output shaft at a 2.318 to 1 ratio.
3rd Gear
Clutch Application Chart
| Gear | Forward (1, 2, 3, 4) | Direct (3, 5, R) | Intermediate (2, 6) | Low / Reverse (1, R) | Overdrive (4, 5, 6) | Low-OWC |
|---|---|---|---|---|---|---|
| 3rd Gear D | D | D | ||||
| Planetary Components | Front planetary carrier-to-No. 3 sun gear | Front carrier-to-No. 2 sun gear | No. 2 sun gear | Rear planetary carrier | Input shaft-to-rear planetary carrier | Rear planetary carrier |
D = Driving
Solenoid Operation Chart
| Selector Lever Position | Commanded Gear | SSA NL (1, 2, 3, 4) | SSB NH (3, 5, R) | SSC NL (2, 6) | SSD NL (1, R) | SSE NH (4, 5, 6) | TCC NL | ||
|---|---|---|---|---|---|---|---|---|---|
| D | 3 | On | Off | Off | Off | On | On/Off (1) | ||
|
|||||||||
NH = Normally High
NL = Normally Low
Powerflow
In 3rd gear, SSA is commanded ON by the PCM/ TCM to apply the forward (1, 2, 3, 4) clutch. SSB is commanded OFF by the PCM/ TCM to apply the direct (3, 5, R) clutch. The forward (1, 2, 3, 4) clutch connects the front carrier to the No. 3 sun gear and the direct (3, 5, R) clutch is applied to transfer power from the front planetary carrier to the No. 2 sun gear, providing a 1.516 to 1 gear ratio.
4th Gear
Clutch Application Chart
| Gear | Forward (1, 2, 3, 4) | Direct (3, 5, R) | Intermediate (2, 6) | Low / Reverse (1, R) | Overdrive (4, 5, 6) | Low-OWC |
|---|---|---|---|---|---|---|
| 4th Gear D | D | D | ||||
| Planetary Components | Front planetary carrier-to-No. 3 sun gear | Front carrier-to-No. 2 sun gear | No. 2 sun gear | Rear planetary carrier | Input shaft-to-rear planetary carrier | Rear planetary carrier |
D = Driving
Solenoid Operation Chart
| Selector Lever Position | Commanded Gear | SSA NL (1, 2, 3, 4) | SSB NH (3, 5, R) | SSC NL (2, 6) | SSD NL (1, R) | SSE NH (4, 5, 6) | TCC NL | ||
|---|---|---|---|---|---|---|---|---|---|
| D | 4 | On | On | Off | Off | Off | On/Off (1) | ||
|
|||||||||
NH = Normally High
NL = Normally Low
Powerflow
In 4th gear, SSA is commanded ON by the PCM/ TCM to apply the forward (1, 2, 3, 4) clutch. SSE is commanded OFF by the PCM/ TCM to apply the overdrive (4, 5, 6) clutch. The forward (1, 2, 3, 4) clutch connects the front carrier to the No. 3 sun gear and the overdrive (4, 5, 6) clutch is applied to transfer power from the input shaft to the rear planetary carrier, providing a 1.149 to 1 gear ratio.
5th Gear
Clutch Application Chart
| Gear | Forward (1, 2, 3, 4) | Direct (3, 5, R) | Intermediate (2, 6) | Low / Reverse (1, R) | Overdrive (4, 5, 6) | Low-OWC |
|---|---|---|---|---|---|---|
| 5th Gear D | D | D | ||||
| Planetary Components | Front planetary carrier-to-No. 3 sun gear | Front carrier-to-No. 2 sun gear | No. 2 sun gear | Rear planetary carrier | Input shaft-to-rear planetary carrier | Rear planetary carrier |
D = Driving
Solenoid Operation Chart
| Selector Lever Position | Commanded Gear | SSA NL (1, 2, 3, 4) | SSB NH (3, 5, R) | SSC NL (2, 6) | SSD NL (1, R) | SSE NH (4, 5, 6) | TCC NL | ||
|---|---|---|---|---|---|---|---|---|---|
| D | 5 | Off | Off | Off | Off | Off | On/Off (1) | ||
|
|||||||||
NH = Normally High
NL = Normally Low
Powerflow
In 5th gear, SSE is commanded OFF by the PCM/ TCM to apply the overdrive (4, 5, 6) clutch. SSB is commanded OFF by the PCM/ TCM to apply the direct (3, 5, R) clutch. The overdrive (4, 5, 6) clutch is applied to transfer power from the input shaft to the rear planetary carrier and the direct (3, 5, R) clutch is applied to transfer power from the front planetary carrier to the No. 2 sun gear, providing a 0.858 to 1 gear ratio.
Fail-safe Mode
Because both SSE and SSB apply the clutches they control when they are turned OFF, 5th gear is the fail-safe. This transmission defaults to 5th gear when certain failures are detected. 5th gear is provided hydraulically with no electrical input.
6th Gear
Clutch Application Chart
| Gear | Forward (1, 2, 3, 4) | Direct (3, 5, R) | Intermediate (2, 6) | Low / Reverse (1, R) | Overdrive (4, 5, 6) | Low-OWC |
|---|---|---|---|---|---|---|
| 6th Gear D | H | D | ||||
| Planetary Components | Front planetary carrier-to-No. 3 sun gear | Front carrier-to-No. 2 sun gear | No. 2 sun gear | Rear planetary carrier | Input shaft-to-rear planetary carrier | Rear planetary carrier |
H = Holding
D = Driving
Solenoid Operation Chart
| Selector Lever Position | Commanded Gear | SSA NL (1, 2, 3, 4) | SSB NH (3, 5, R) | SSC NL (2, 6) | SSD NL (1, R) | SSE NH (4, 5, 6) | TCC NL |
|---|---|---|---|---|---|---|---|
| D | 6 | Off | On | On | Off | Off | On/Off |
NH = Normally High
NL = Normally Low
Powerflow
In 6th gear, SSE is commanded OFF by the PCM/ TCM to apply the overdrive (4, 5, 6) clutch. SSC is commanded ON to apply the intermediate (2, 6) clutch. The overdrive (4, 5, 6) clutch is applied to transfer power from the input shaft to the rear planetary carrier and the intermediate (2, 6) clutch is applied to hold the No. 2 sun gear, transferring power through the rear planetary carrier to the rear ring gear/output shaft at a 0.674 to 1 ratio.