To the top of the document
Captiva
To Previous PageTo Next Page
GMDE Start PageLoad static TOCLoad dynamic TOCHelp?

GENERAL DESCRIPTION AND SYSTEM OPERATION

Transaxle Description

The new automatic transmission (AISIN 55-51LE) is an electronically controlled five-speed automatic transmission.
The transmission is mainly composed of the torque converter, the planetary gear unit, the hydraulic control system and the electric control system.

Electronical Components

Transmission Control Module (TCM)

The TCM primarily controls shift points and lockup engagement. It is located on the driver side under the instrument panel.
The transmission is controlled by an electronic shift system. The Transmission Control Module (TCM) processes input signals. From the information received, the TCM controls the transmission hydraulic system.
The electronic shift system consists of the following :

Transmission Range (TR) Switch

Transmission Range (TR) Switch transmits the information which range includes shift lever of A/T to Starter and TCM.
TR switch transmits the information by combination of starter and reverse circuit to vehicle side directly without TCM.

C7A15A15
Display graphicTranslations of text in graphics



L7B53A02
Display graphicTranslations of text in graphics


Shift Solenoid No 1, 2, 3, 4, 5 (SS1, SS2, SS3, SS4, SS5)

5 shift solenoids are installed directly in the valve body. The solenoids operate of ON and OFF by the control signal from TCM. Combinations of 5 solenoids, SS1, SS2, SS3, SS4 and SS5 changes gear ranges.

L7B53A03
Display graphicTranslations of text in graphics


Line Pressure Control Solenoid (SLT)

Line pressure control solenoid (SLT) controls linear throttle pressure by control signal from TCM and line pressure for clutches and brakes to reduce shift shock.

L7B53A08
Display graphicTranslations of text in graphics


TCC Lock-up Control Solenoid (SLU)

TCC lock up control solenoid (SLU) controls linear SLU pressure by control signal from TCM and hydraulic pressure for lock-up clutch to reduce shift shock.
<Direct control>
1st engine brake - 1st and reverse brake (B3)
2nd - 2nd brake (B2)

L7B53A10
Display graphicTranslations of text in graphics


Shift Pressure Control Solenoid (SLS)

Shift pressure control solenoid (SLS) controls linear SLS pressure by control signal from TCM.
<Direct control>
2nd, 3rd, 4th - 2nd coast brake (B1)
5th, Reverse - Direct clutch (C2)

L7B53A12
Display graphicTranslations of text in graphics


Transmission Fluid Temperature (TFT) Sensor

TFT sensor is located in the valve body.
TFT sensor provides TCM with information on the transmission fluid temperature.
The TCM uses information from the TFT sensor to calculate the gear shift points and to engage the torque converter lockup function.

L7B53A06
Display graphicTranslations of text in graphics


Input Shaft Speed (ISS) Sensor

ISS sensor (1) is located on the upper position of the transaxle and detects A/T input speed from the rotation number of the direct clutch drum (2).
They transmit to TCM as a signal.

L7B53A05
Display graphicTranslations of text in graphics


Output Shaft Speed (OSS) Sensor

OSS sensor (1) is located on the upper position of the transaxle and detects the vehicle speed from the rotation number of the parking gear (2).

L7B53A04
Display graphicTranslations of text in graphics


Hydraulic Control System

Based on the hydraulic pressure created by the oil pump, TCM sends signals to solenoid and hydraulic control system governs the hydraulic pressure acting on the torque converter, planetary gear, clutches and brakes in accordance with the vehicle driving conditions.

T3B15AY4
Display graphicTranslations of text in graphics


Automatic Transaxle System

Function of Components


L7B53A15
Display graphicTranslations of text in graphics


Clutch & Brake
Operation
C1
Forward clutch (1)
Connects input shaft and rear ring gear.
C2
Direct clutch (2)
Connects input shaft to rear sun gear.
C3
Underdrive clutch (3)
Connect underdrive sun gear to underdrive front carrier.
B1
2nd coast brake (4)
Lock front sun gear.
B2
2nd brake (5)
Lock counterclockwise rotation of front sun gear.
B3
1st & reverse brake (6)
Lock front ring gear.
B4
Underdrive brake (7)
Lock underdrive sung gear.
B5
B5 brake (8)
Lock underdrive rear carrier.
F1
1 way clutch No.1 (9)
Lock counterclockwise rotation of front sun gear, when B2 operations.
F2
1 way clutch No.2 (10)
Lock counterclockwise rotation of front ring gear.

Operations of Clutches and Brakes


L7B15A09
Display graphicTranslations of text in graphics


Position
Solenoid
Clutch
Brake
1Way clutch
S1
S2
S3
S4
S5
C1
C2
C3
B1
B2
B3
B4
B5
F1
F2
P
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
ON
OFF
OFF
R
V<=7
OFF
OFF
ON
OFF
ON
OFF
ON
OFF
OFF
OFF
ON
OFF
ON
OFF
OFF
V>7
ON
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
ON
OFF
OFF
N
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
ON
OFF
OFF
D, M
D
1st
ON
ON
ON
OFF
OFF
ON
OFF
OFF
OFF
OFF
OFF
OFF
ON
OFF
ON
M
1st
ON
ON
ON
OFF
ON
ON
OFF
OFF
OFF
OFF
ON
OFF
ON
OFF
ON
2nd
OFF
OFF
ON
OFF
OFF
ON
OFF
OFF
ON
ON
OFF
OFF
ON
ON
OFF
3rd
OFF
OFF
ON
ON
OFF
ON
OFF
OFF
ON
ON
OFF
ON
OFF
ON
OFF
4th
OFF
OFF
OFF
ON
OFF
ON
OFF
ON
ON
ON
OFF
OFF
OFF
ON
OFF
5th
OFF
ON
OFF
ON
OFF
ON
ON
ON
OFF
ON
OFF
OFF
OFF
OFF
OFF
4
1st
ON
ON
ON
OFF
OFF
ON
OFF
OFF
OFF
OFF
OFF
OFF
ON
OFF
ON
2nd
OFF
OFF
ON
OFF
OFF
ON
OFF
OFF
ON
ON
OFF
OFF
ON
ON
OFF
3rd
OFF
OFF
ON
ON
OFF
ON
OFF
OFF
ON
ON
OFF
ON
OFF
ON
OFF
2
1st
ON
ON
ON
OFF
ON
ON
OFF
OFF
OFF
OFF
ON
OFF
ON
OFF
ON
2nd
OFF
OFF
ON
OFF
OFF
ON
OFF
OFF
ON
ON
OFF
OFF
ON
ON
OFF

D-1st Gear

Position
Solenoid
Clutch
Brake
1 way Clutch
S1
S2
S3
S4
S5
C1
C2
C3
B1
B2
B3
B4
B5
F1
F2
D
1st
ON
ON
ON
OFF
OFF
ON
OFF
OFF
OFF
OFF
OFF
OFF
ON
OFF
ON

L7B15A10
Display graphicTranslations of text in graphics


"D" - 1st Gear

  1. Input shaft rotates clockwise.
  2. Rear planetary ring gear rotates clockwise.
  3. Rear planetary pinion rotates itself clockwise.
  4. Front large planetary pinion rotates itself clockwise for rear planetary pinion and one.
  5. Front small planetary pinion rotates itself counterclockwise.
  6. Front ring gear is going to rotate counterclockwise.
  7. Front & rear planetary carrier revolves clockwise due to reaction force of front small pinion.
  8. Counter drive gear rotates clockwise for front & rear planetary carrier and one.
  9. Counter driven gear rotates counterclockwise.
  10. Front planetary ring gear rotates counterclockwise for counter driven gear and one.
  11. Front planetary pinion rotates itself counterclockwise.
  12. Front planetary sun gear rotates clockwise.
  13. Rear planetary sun gear rotates clockwise for front planetary sun gear and one.
  14. Rear planetary pinion rotates itself counterclockwise.
  15. Rear planetary ring gear rotates counterclockwise.
  16. Front carrier and differential drive pinion gear rotates counterclockwise for rear ring gear and one.
  17. Differential rotates clockwise.
( Engine Brake)
  1. Counter drive gear and main front & rear planetary carrier rotates clockwise.
  2. Rear planetary carrier rotates clockwise, but rear planetary pinion revolves clockwise while rotating itself counterclockwise due to resistance of rear planetary ring gear.
  3. Front large pinion revolves clockwise while rotating itself counterclockwise and front small pinion revolves clockwise while rotating itself clockwise. And front carrier revolves clockwise.
  4. Front ring gear rotates clockwise due to rotation itself clockwise of front small pinion, but driving force loses due to free of F2. Therefore engine brake does not operate.

D-2nd Gear

Position
Solenoid
Clutch
Brake
1 way Clutch
S1
S2
S3
S4
S5
C1
C2
C3
B1
B2
B3
B4
B5
F1
F2
D
2nd
OFF
OFF
ON
OFF
OFF
ON
OFF
OFF
ON
ON
OFF
OFF
ON
ON
OFF

L7B15A11
Display graphicTranslations of text in graphics


"D" - 2nd Gear

  1. Input shaft rotates clockwise.
  2. Rear planetary ring gear rotates clockwise.
  3. Rear planetary pinion rotates itself clockwise.
  4. Front large planetary pinion rotates itself clockwise for rear planetary pinion and one.
  5. Front & rear planetary carrier revolves clockwise due to reaction force of front large pinion.
  6. Counter drive gear rotates clockwise for front & rear planetary carrier and one.
  7. Counter driven gear rotates counterclockwise.
  8. Front planetary ring gear rotates counterclockwise for counter driven gear and one.
  9. Front planetary pinion rotates itself counterclockwise.
  10. Front planetary sun gear rotates clockwise.
  11. Rear planetary sun gear rotates clockwise for front planetary sun gear and one.
  12. Rear planetary pinion rotates itself counterclockwise.
  13. Rear planetary ring gear rotates counterclockwise.
  14. Front carrier and differential drive pinion gear rotates counterclockwise for rear ring gear and one.
  15. Differential rotates clockwise.
( Engine Brake)
  1. Driving force is connected to input shaft directly without 1 way clutch. Therefore engine brake operates.

D-3rd Gear

Position
Solenoid
Clutch
Brake
1 way Clutch
S1
S2
S3
S4
S5
C1
C2
C3
B1
B2
B3
B4
B5
F1
F2
D
3rd
OFF
OFF
ON
ON
OFF
ON
OFF
OFF
ON
ON
OFF
ON
OFF
ON
OFF

L7B15A12
Display graphicTranslations of text in graphics


"D" - 3rd Gear

  1. Input shaft rotates clockwise.
  2. Rear planetary ring gear rotates clockwise.
  3. Rear planetary pinion rotates itself clockwise.
  4. Front large planetary pinion rotates itself clockwise for rear planetary pinion and one.
  5. Front & rear planetary carrier revolves clockwise due to reaction force of front large pinion.
  6. Counter drive gear rotates clockwise for front & rear planetary carrier and one.
  7. Counter driven gear rotates counterclockwise.
  8. Front planetary ring gear rotates counterclockwise for counter driven gear and one.
  9. Front planetary pinion rotates itself counterclockwise.
  10. Front planetary carrier revolves counterclockwise due to reaction force of front planetary pinion.
  11. Rear ring gear and differential drive pinion gear rotates counterclockwise for front carrier and one.
  12. Differential rotates clockwise.
( Engine Brake)

D-4th Gear

Position
Solenoid
Clutch
Brake
1 way Clutch
S1
S2
S3
S4
S5
C1
C2
C3
B1
B2
B3
B4
B5
F1
F2
D
4th
OFF
OFF
OFF
ON
OFF
ON
OFF
ON
ON
ON
OFF
OFF
OFF
ON
OFF

L7B15a13
Display graphicTranslations of text in graphics


"D" - 4th Gear

  1. Input shaft rotates clockwise.
  2. Rear planetary ring gear rotates clockwise.
  3. Rear planetary pinion rotates itself clockwise.
  4. Front large planetary pinion rotates itself clockwise for rear planetary pinion and one.
  5. Front & rear planetary carrier revolves clockwise due to reaction force of front large pinion.
  6. Counter drive gear rotates clockwise for front & rear planetary carrier and one.
  7. Counter driven gear rotates counterclockwise.
  8. Front planetary ring gear rotates counterclockwise for counter driven gear and one.
  9. Front planetary pinion can not rotate itself, and underdrive unit rotates counterclockwise as one.
  10. Differential drive pinion gear rotates counterclockwise for underdrive unit and one.
  11. Differential rotates clockwise.
<Engine Brake>
  1. Driving force is connected to input shaft directly without 1 way clutch. Therefore engine brake operates.

D-5th Gear

Position
Solenoid
Clutch
Brake
1 way Clutch
S1
S2
S3
S4
S5
C1
C2
C3
B1
B2
B3
B4
B5
F1
F2
D
5th
OFF
ON
OFF
ON
OFF
ON
ON
ON
OFF
ON
OFF
OFF
OFF
OFF
OFF

L7B15A14
Display graphicTranslations of text in graphics


"D" - 5th Gear

  1. Input shaft rotates clockwise.
  2. Rear planetary pinion can not rotate itself, and rear planetary unit rotates clockwise as one.
  3. Front large planetary pinion can not rotate itself for rear planetary pinion and one, and front planetary unit rotates clockwise as one.
  4. Counter drive gear rotates clockwise for front planetary unit and one.
  5. Counter driven gear rotates counterclockwise.
  6. Front planetary ring gear rotates counterclockwise for counter driven gear and one.
  7. Front planetary pinion can not rotate itself, and underdrive unit rotates counterclockwise as one.
  8. Differential drive pinion gear rotates counterclockwise for underdrive unit and one.
  9. Differential rotates clockwise.
<Engine Brake>
  1. Driving force is connected to input shaft directly without 1 way clutch. Therefore engine brake operates.

Reverse Gear

Position
Solenoid
Clutch
Brake
1 way Clutch
S1
S2
S3
S4
S5
C1
C2
C3
B1
B2
B3
B4
B5
F1
F2
R
V<=7km/h
OFF
OFF
ON
OFF
ON
OFF
ON
OFF
OFF
OFF
ON
OFF
ON
OFF
OFF
V>7km/h
ON
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
OFF
ON
OFF
OFF

L7B15A15
Display graphicTranslations of text in graphics


Reverse Gear

  1. Input shaft rotates clockwise.
  2. Rear planetary sun gear rotates clockwise.
  3. Rear planetary pinion rotates itself counterclockwise.
  4. Front large planetary pinion rotates itself counterclockwise for rear planetary pinion and one.
  5. Front small planetary pinion rotates itself clockwise.
  6. Front & rear carrier revolves counterclockwise due to reaction force of front small pinion.
  7. Counter drive gear rotates counterclockwise for front & rear planetary carrier and one.
  8. Counter driven gear rotates clockwise.
  9. Front planetary ring gear rotates clockwise for counter driven gear and one.
  10. Front planetary pinion rotates itself clockwise.
  11. Front planetary sun gear rotates counterclockwise.
  12. Rear planetary sun gear rotates counterclockwise for front planetary sun gear and one.
  13. Rear planetary pinion rotates itself clockwise.
  14. Rear planetary ring gear rotates clockwise.
  15. Front carrier and differential drive pinion gear rotates clockwise for rear ring gear and one.
  16. Differential rotates counterclockwise.
<Engine Brake>
  1. Driving force is connected to input shaft directly without 1 way clutch. Therefore engine brake operates.

Control Functions of TCM

Shift Control and Lock-up Control

According to each shift schedule, TCM sends signals to the S1, S2, S3, S4, S5 which operates ON/OFF control "Shift Control" and the TCC lock up control solenoid (SLU) which operates linear control "Lock-up Control" on the basis of the vehicle speed and the throttle opening.
<Each solenoid operation>
Gear
S1
S2
S3
S4
S5
1st
ON
ON
ON
OFF
OFF
2nd
OFF
OFF
ON
OFF
OFF
3rd
OFF
OFF
ON
ON
OFF
4th
OFF
OFF
OFF
ON
OFF
5th
OFF
ON
OFF
ON
OFF
55-51LE for automatic transaxle does not have several driving mode that user can select. Basically TCM programmed for "Economy mode", but TCM changes to several shift schedule automatically according to specified condition. But, only "Winter mode" can be chosen by the switch.
  1. Driver's adaptive shift control (Economy, Medium, Sport mode)
    2. Economy mode is used for normal driving condition after ignition ON. And driver's liking is detected by using fuzzy logic from accelerator operation. This control changes shift points to Economy (low speed), Medium(middle speed) and Sport(high speed) according to the liking degree.
Start (1) & (2)
(1) "D"
(2) Vehicle speed >= 5 km/h (3 mph)
End (1) or (2) or (3)
(1) Except "D"
(2) Vehicle speed > 240 km/h (149 mph)
(3) Driver's liking detection is Economy mode
  1. Winter mode
    2. This mode is used for vehicle start on a slippery road due to pushing the winter mode switch. (Vehicle start in 3rd gear)
Range
Winter
D
3(L) ↔ 4(L) ↔ 5(L)
↔: Shift up/down, (L) : Lock-up Operation
  1. Upslope mode
    2. When TCM detects upslope from load of engine torque and decrease of acceleration, this mode changes shift points in high-speed side according to the upslope degree and avoids busy shift of A/T.
  2. Downslope mode
    3. When TCM detects downslope from increase of acceleration with accelerator full close, this mode operates moderate engine brake by changing shift points in high-speed side.
  3. Hot mode control
    4. This control lowers ATF temperature by changing shift points when the temperature is extremely high. (ATF temperature > 140°C (284°F))
  4. Altitude control
    5. This control makes up for low engine power by establishing shift points at a slightly higher vehicle speed range in high altitude where air pressure is low.
  5. Cold offset control
    6. This control makes up for low engine torque by establishing shift points at a slightly higher vehicle speed range when air temperature is extremely low. (Engine coolant temperature < -30°C (-22°F))

Manual Shift Control (Tap Mode)

Driver oneself can select favorite gear and enjoy sports driving of manual transmission sense by shifting shift lever from "D" to manual gear position and Manual+(Up shift) / Manual-(Down shift). But lock-up control is operated automatically. Shift control is operated again by shifting from manual gear position to "D".

Lock-up Cut Control

This control cuts lock-up operation at shift down or idle condition and avoid engine stall by depressing brake pedal at low speed driving.

Up/Down Learning Control

This control learns the pressure to each clutch or brake in order to reduce shifting shock at each shifting (Up, Down, Manual down, Coast down).
<Learning control method>
(1) 65°C (149°F) =< Oil temperature < 110°C (230°F)
(2) Constant low throttle opening (about 20-30%)
(3) Plenty shifting interval (about 3 sec)
(4) Repeat each shifting about 10 times

N-D Shift Control

This control improves the N-D shift quality due to controlling line pressure control solenoid according to forward clutch (C1) piston stroke learned in N-D learning control and applying best hydraulic pressure to forward clutch (C1) at N-D shift.

N-D Learning Control

This control learns the forward clutch (1) hydraulic pressure due to monitoring a forward clutch (1) engaging time and a rotation change rate.
Start (1) & (2) & (3) & (4)
(1) 500 rpm =< Engine speed < 1,200 rpm
(2) 65°C (149°F) =< Oil temperature < 110°C (230°F)
(3) 450 rpm =< forward clutch (C1) revolution < 1,200 rpm
(4) Throttle opening < 3.0 %
<Learning control method>
(1) When above start condition
(2) Shifting interval more than 3 sec
(3) Repeat N-D shifting about 10 times

N-R Shift Control

This control improves the N-R shift quality due to controlling shift pressure control solenoid according to direct clutch (C2) piston stroke learned in N-R learning control and applying best hydraulic pressure to C2 clutch at N-R shift.

N-R Learning Control

This control learns the direct clutch (C2) hydraulic pressure due to monitoring a C2 clutch engaging time and a rotation change rate.
Start (1) & (2) & (3) & (4)
(1) 500 rpm =< Engine speed < 1,200 rpm
(2) 65°C (149°F) =< Oil temperature < 110°C (230°F)
(3) 450 rpm =< forward clutch (C1) revolution < 1,200 rpm
(4) Throttle opening < 3.0 %
<Learning control method>
(1) When above start condition
(2) Shifting interval more than 3 sec
(3) Repeat N-R shifting about 10 times

Torque Reduction Control

This control improves the shift quality due to sending torque reduction request signal from TCM to ECM and cutting engine torque increase of shift at N-D shift, N-R shift and 1↔2↔3↔4↔5.
If accelerator pedal is depressed rapidly, this control establishes the upper limit value of engine torque and avoids "Engine flare" at 2↔3, 3↔4 and 4=>2 of "clutch to clutch shift".

Transmission Adaptive Learn Procedure

Perform the transmission adaptive learn procedure after any of the following service procedures :
  1. Drive the vehicle to warm the transaxle fluid until 65-110°C (150-230°F). The adaptive learn procedure will not work unless transaxle fluid is the correct temperature.
  2. Reset the transaxle adaptive learns using a scan tool.
  3. Perform the following steps for the garage shifts adaptive learn.
    1. Apply the parking brake and the foot brake.
    2. Shift from NEUTRAL to REVERSE and keep in REVERSE for 3 seconds.
    3. Shift from REVERSE to NEUTRAL.
    4. Repeat the above two steps five times.
    5. Shift from NEUTRAL to DRIVE and keep in DRIVE for 3 seconds.
    6. Shift from DRIVE to NEUTRAL.
    7. Repeat the above two steps five times.
  4. Perform the following steps for the Up/Down shifting adaptive learn.
    1. Drive the vehicle in DRIVE with light (15-20 percent) throttle until above 50 km/h (31 mph) in 4th gear.
    2. Decelerate and apply the brakes until vehicle comes to a stop. Brake the vehicle so that it takes at least 14 seconds.
    3. Repeat the above steps five times.
Perform the following steps for 4→2 Manual down shift adaptive learn (No Tap shift).
  1. Drive the vehicle in "4" until over 25 km/h (16 mph) in 2nd with any throttle position.
  2. Decelerate, shift from "4" to "2" manually and stop the vehicle.
  3. Repeat the above two steps ten times.
Perform the following steps for 2→1 Tap down shift adaptive learn (Tap shift).
  1. Drive the vehicle in "Tap 2" until over 25 km/h (16 mph) in 2nd with any throttle position.
  2. Decelerate, shift from "Tap 2" to "Tap 1" manually and stop the vehicle.
  3. Repeat the above two steps ten times.

Important : If shift quality does not improve, ensure the TCM has the correct transmission calibration.

  1. Confirm shift quality.


To Previous PageTo Next Page
© Copyright Chevrolet Europe. All rights reserved