5A-44 AUTOMATIC TRANSMISSION
CLUTCH PACKS
There are four clutch packs (refer to figure 4.3). All clutch packs are composed of multiple steel and friction plates.
C1 CLUTCHWhen applied, this clutch pack allows the input shaft to drive the planet carrier.
This occurs in third and fourth gears.
C2 CLUTCHWhen applied this clutch pack allows the input shaft to drive the forward sun gear via the 3-4 OWC.
This occurs in all forward gears.
C3 CLUTCHWhen applied this clutch pack allows the input shaft to drive the reverse sun gear. This only occurs in
reverse gear.
C4 CLUTCHWhen applied this clutch provides engine braking on overrun. This occurs in Manual 1, 2 and 3 and
also Drive 2 and Drive 3 to prevent objectionable free wheel coasting.
Figure 4.3 - Clutch Packs
5A-50 AUTOMATIC TRANSMISSION
POWER FLOW - MANUAL 1
In Manual 1, transmission drive is via the input shaft
to the forward clutch cylinder. The elements of the
transmission function as follows :
lThe C2 clutch is engaged to drive the forward sun gear, via the 3-4 OWC.
lThe B2 band is engaged to hold the planetary gear carrier stationary.
lThe forward sun gear drives the short pinion anti-clockwise.
lThe short pinion drives the long pinion clockwise.
lThe long pinion rotating about its axis drives the internal ring gear and the output shaft in a clockwise or
forward direction.
lThe C4 clutch provides engine braking through the 3-4 OWC on overrun.
Control
To maintain this arrangement in the steady state solenoids and valves are activated as follows:
lSolenoids S1 and S2 are switched ON.
lThe 1-2,2-3, and 34 shift valves are held in their first gear positions by line 500 pressure.
lDrive (line pressure) oil from the manual valve engages the C2 clutch.
lLo-1st (line pressure) oil is routed through the 1-2 shift valve to the C4 clutch, and to the inner apply area of
the rear servo piston for B2 band application.
Refer to figure 5.3 and table 5.4.
Table 5.4 - Engaged Elements - Manual 1
Gear State
Manual 1C1
-C2
XC3
-C4
XB1
-B2
X1-2
OWC
-3-4
OWC
XLU
CLUTCH
- ELEMENTS ENGAGED
AUTOMATIC TRANSMISSION 5A-51
POWER FLOW - DRIVE 1
In Drive 1, transmission drive is via the input shaft to the forward clutch cylinder. The elements of the transmission
function as follows :
lThe C2 clutch is engaged to drive the forward sun gear.
lThe forward sun gear drives the short pinion anti-clockwise.
lThe short pinion drives the long pinion clockwise.
lThe 1-2 OWC prevents the planetary gear carrier from rotating under reaction force and the long pinion
rotates on its axis driving the internal ring gear and output shaft in a clockwise or forward direction.
lThere is no engine braking on overrun.
Control
To maintain this arrangement in the steady state solenoids and valves are activated as follows:
lSolenoids S1 and S2 are switched On.
lThe 1-2, 2-3, and 3-4 shift valves are held in their first gear positions by line 500 pressure.
lDrive (line pressure) oil from the manual valve engages the C2 clutch.
Refer to figure 5.4 and table 5.5
Table 5.5 - Engaged Elements - Drive 1
Gear State
Drive 1C1
-C2
XC3
-C4
-B1
-B2
-1-2
OWC
X3-4
OWC
XLU
CLUTCH
- ELEMENTS ENGAGED
5A-52 AUTOMATIC TRANSMISSION
POWER FLOW - DRIVE 2 AND MANUAL 2
In Drive 2 and Manual 2, transmission drive is via the input shaft and forward clutch cylinder. The elements of the
transmission function as follows :
lThe C2 clutch is applied to drive the forward sun gear.
lThe forward sun gear drives the short pinion anti-clockwise.
lThe short pinion drives the long pinion clockwise.
lThe B1 band is applied holding the reverse sun gear stationary therefore the long pinion ‘walks’ around the
reverse sun gear taking the internal ring gear and output shaft with it in a clockwise or forward direction.
lThe C4 clutch is applied to bypass the 3-4 OWC and provide engine braking on overrun.
Control
To maintain this arrangement in the steady state solenoids and valves are activated as follows: Solenoid S1 is
switched Off. S2 is switched On.
lSolonoid S1 is switched Off. S2 is switched On.
lDrive (line pressure) oil from the manual valve engages the C2 clutch.
lWhen S1 switches off , S1 oil pressure, which is derived from line 500 pressure, moves the 3-4 shift valve to
the left. At the same time S1 oil is directed to the 1-2 shift valve which moves the valve to the second gear
position.
l2nd oil (line pressure) from the 1-2 shift valve is directed to the band apply regulator valve, and to the 2-3 shift
valve.
lThe band apply regulator valve supplies 2nd oil (regulated to line pressure multiplied by the valve ratio) to the
band apply feed (BAF) circuit.
lBand apply feed oil is directed to:
- The outer apply area of the front servo
- The 1-2 shift valve to provide an exhaust port when the transmission is shifted to first gear
- The 3-4 shift valve for use when the transmission is shifted into fourth gear
lDrive (line pressure) is routed through the 3-4 shift valve to apply the C4 clutch.
Refer to figure 5.5 and table 5.6.
Table 5.6 - Engaged Elements - Drive 2 and Manual 2
Gear State
Drive 2 and Manual 2C1
-C2
XC3
-C4
XB1
XB2
-1-2
OWC
-3-4
OWC
XLU
CLUTCH
- ELEMENTS ENGAGED
5A-54 AUTOMATIC TRANSMISSION
POWER FLOW - DRIVE 3 AND MANUAL 3
In Drive 3 and Manual 3, transmission drive is via the input shaft to the forward clutch cylinder. The elements of the
transmission function as follows :
lThe C2 clutch is engaged to drive the forward sun gear.
lThe C1 clutch is engaged to drive the planet carrier.
lThe forward sun gear and the planet carrier are driven clockwise at the same speed therefore there is no
relative motion between the sun gear and the pinions.
lThe ring gear and output shaft are driven in a clockwise or forward direction at input shaft speed.
lThe C4 clutch is applied to bypass the 3-4 OWC and provide engine braking on overrun.
Control
To maintain this arrangement in the steady state solenoids and valves are activated as follows:
lSolenoid S1 is switched Off. S2 is switched Off.
lWith S1 and S2 switched Off, the 2-3 and 3-4 shift valves are held in the third gear position by line 500
pressure.
lThe 1-2 shift valve is held in the third gear position by S1-S2 oil pressure.
l2nd oil (line pressure) from the 1-2 shift valve is directed to the band apply regulator valve. and to the 2-3 shift
valve.
lThe band apply regulator valve supplies 2nd oil (regulated to line pressure multiplied by the valve ratio) to the
band apply feed (BAF) circuit.
lBand apply feed oil is directed to:
- The outer apply area of the front servo
- The 1-2 shift valve to provide an exhaust port when the transmission is shifted to first gear
- The 3-4 shift valve for use when the transmission is shifted into fourth gear
l2nd oil at the 2-3 shift valve is directed to the 3rd oil circuit.
l3rd oil from the 2-3 shift valve is directed to the clutch apply regulator valve, and to the 4-3 Sequence Valve.
lThe clutch apply regulator valve supplies oil (regulated to line 500 pressure multiplied by the valve ratio) to the
clutch apply feed (CAF) circuit.
l The CAF oil is directed to:
- The C1 clutch
- The C1 bias valve
- The 4-3 sequence valve
lAt the 4-3 sequence valve the CAF oil becomes band 1 release feed (B1R-F) oil, and is directed through the
3-4 shift valve to the spring end of the 4-3 sequence valve, and to the release side of the front servo piston to
hold band 1 off.
lDrive (line pressure) is routed through the 3-4 shift valve to apply the C4 clutch.
Refer to figure 5.6 and table 5.7.
Table 5.7 - Engaged Elements - Drive 3 and Manual 3
Gear State
Drive 3 and Manual 3C1
XC2
XC3
-C4
XB1
-B2
-1-2
OWC
-3-4
OWC
XLU
CLUTCH
- ELEMENTS ENGAGED
5A-60 AUTOMATIC TRANSMISSION
DIAGNOSIS
DIAGNOSTIC SYSTEM
Recommended Test Equipment and Procedure
The test equipment is designed to be used with the control modules in all vehicles. The components used in the
transmission application are:
lMulti Function Tester, and
lAppropriate vehicle for testing.
Multi Function Tester (MFT)
The MFT is programmed with the special vehicle diagnostic software that allows selection of the unit under test.
The program allows the proper communication to the Transmission Control Unit (TCU).
It then requests information from the user via a menu system to select the required set up.
Examples are viewing codes, clearing error codes, and real-time operation. Set up and operation instructions are
detailed in the user manual.
This equipment can be used by trained personnel such as technicians and mechanics to diagnose electronic and
wiring problems relating to the vehicle transmission. Information that is available includes engine and road (shaft)
speed, transmission oil temperature, throttle position, solenoid/gear status and gear lever position. Current and
stored faults detected by the electronics are also available.
TCU Pin Description
The TCU pin descriptions are listed in table 6.1.1.
The wiring loom pins are shown in figure 6.1.1
Pin
No.
1
2
3
4
5
6
7
8Identification
Common Ground
Do not use
Mode Indicator Lamp -
‘Winter’
Gear Position ‘Park’
Lamp
Gear Position ‘Reverse’
Lamp
Gear Position ‘Neutral’
Lamp
Do not use
Engine Speed Input
Sensor (-Ve)Type
GND
-
OP
OP
OP
OP
-
IPDescription
Main power ground (or the module. Connects
directly to the battery negative terminal.
Indicates ‘WINTER’ mode shift schedule is se-
lected.
Drives the jewel in the instrument cluster to in-
dicate ‘PARK’ gear lever position.
Drives the jewel in the instrument cluster to in-
dicate ‘REVERSE’ gear lever position.
Drives the jewel in the instrument cluster to in-
dicate ‘NEUTRAL’ gear lever position.
Flywheel/Ring gear pulses to indicate engine
speed. 4WD
(Diesel)
O
O
l
l l l
l
4WD
(Gas)
O
O
O
l
l l l
l
l
Table 6.1.1 - TCU Pin Description
AUTOMATIC TRANSMISSION 5A-61
Pin
No.
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30Identification
Mode Indicator Lamp -
‘Power’
Throttle Position Sensor
Output as Pulse Width
Modulation for TOD
Air Conditioner Input Signal
Kickdown Switch
Mode Switch
Transfer Case Input
(High) -4WD Lamp High
Ignition Switch
Do not use
Gear Position ‘1’ Lamp/
Gear Position Code 1
*Gear Position ‘2’ Lamp/
Gear Position Code 2*
Gear Position ‘3’ Lamp/
Gear Position Code 3*
Gear Position ‘Drive’
Lamp/
Gear Position Code 4*
CAN (-ve)
CAN (+ve)
K-line Communication Link
Engine Speed Input
Sensor (+ve)
Road Speed Pulses
Shaft Speed Sensor
Signal
Throttle Position Sensor -
Ground
Throttle Position Sensor -
Reference
Throttle Position Sensor -
Input Signal
Transfer(or Case Input
(Low) - 4WD Lamp LowType
OP
OP
-
IP
IP
IP
IP
-
OP
OP
OP
OP
I/O
I/O
I/O
IP
OP
IP
GND
REF
IP
IPDescription
Indicates ‘POWER’ mode shift schedule is se-
lected.
Provides an analogue signal of the throttle po-
sition for the Torque on Demand (TOD) Con-
trol Module.
Input
Switch to indicate when a kickdown is required
at high throttle position.
Switch to select ‘NORMAL’, ‘POWER’ or ‘WIN-
TER’ shift schedule.
Voltage varies from OV to 12V.
Switch to indicate 4WD’HIGH RANGE’ is se-
lected.
Ignition power is used as the main power source
to drive the unit and the solenoids.
Drives jewel in the instrument cluster to indi-
cate
gear leverposition’1'. Drives jewel in the instru-
ment cluster to indicate
gear lever position’2'. Drives jewel in the instru-
ment cluster to indicate gear lever position’3'.
Drives jewel in the instrument cluster to indi-
cate
‘DRIVE’. gear lever position.
CAN low side bus communication (CANL).
CAN high side bus communication (CANH).
Diagnostic information and vehicle coding.
Flywheel/Ring gear pulses to indicate engine
speed.
Road speed signals derived from shaft speed
sensors.
This sensor transmit shaft speed signal to the
TCU.
Throttle position sensor ground.
This is the 5V reference voltage supply gener-
ated by the unit for the throttle position sensor.
This sensor is a resistance potentiometer indi-
cating throttle position.
Voltage varies 0V to 5V.
Switch to indicate 4WD’LOW RANGE’ is se-
lected. 4WD
(Diesel)
O
O
O
O
l
l
l
4WD
(Gas)
O
O
O
O
O
O
O
O
l
l
l
ll
ll
ll
ll
ll
ll
l
l
ll
l
ll
l
l
l
l
ll l
5A-64 AUTOMATIC TRANSMISSION
Default Transmission Operating Modes
The TCU relies on accurate information from its inputs and complete control of its outputs to effectively control the
transmission. To ensure that it has both valid inputs and functioning outputs, the TCU carries out both hardware and
software fault detection routines. The TCU will respond to any faults detected by adopting the operating modes which
are detailed below.
The following symptoms of faults are the most obvious results of each fault under ‘normal’ conditions.
There is always the possibility that a fault may not be detected. If undetected fault conditions are present, the
operation of the transmission is difficult to predict.
1 Throttle Fault
lAll shifts will occur as if a nominal throttle (approx. 44%) were applied for shift scheduling.
lAll shifts will be firm as full throttle and hence high engine torque is assumed.
lThe torque converter will be unlocked at all times.
lAll downshifts initiated by the shift lever will occur as though they were ‘automatic’ shifts. That is the engine
braking effect will not occur until near the end of the shift.
lLine pressure will always stay high (solenoid 6 OFF) to cope with assumed high throttle/torque.
If a fault is undetected, the percent throttle is most likely to be interpreted as higher than actual, resulting in late
upshifts, early downshifts, firm shifting and a harsh 3-1 shift when stopping.
2 Throttle Not Learnt Fault
The transmission operates from default throttle calibration values which results in the evaluation of the throttle being
higher (more open) than it is. There(ore at zero throttle settings, the transmission may calculate that sufficient throttle
opening is present to justify high line pressure and switch solenoid 6 to OFF.
Other symptoms are:
a. late upshifts and
b. lock-up maintained at zero throttle when the vehicle speed is sufficiently high.
3 Engine Speed Fault
lAll shifts will be firm because an engine speed corresponding to peak engine torques is assumed.
If a fault is undetected, the engine speed is likely to be interpreted as stalled resulting in soft shifting possibly with an
end of shift bump.
4 Vehicle Speed Sensor Fault
lAll shifts will be controlled by the shift lever with skip downshifts disabled and downshifts only allowed if the
engine speed is low. Fourth gear will be inhibited.
lThe torque converter will be unlocked at all times.
If a fault is undetected, the vehicle is likely to be interpreted as being stationary resulting in first gear operation at all
times. Note that speedometer transducer faults are likely to cause the vehicle’s speedometer to become inoperative.
5 Gear Lever Fault (Inhibitor/PRNDL Switch)
lThe gear lever is assumed to be in the Drive position.
lThe transmission is limited to 2nd,3rd, and R gears only.
lThe rear band will apply at all times when the lever is shifted to P, R or N. (B2 inhibition and reverse lockout
protection is disabled.)
lThe torque converter will be unlocked at all times.
lManually (gear lever) initiated downshifts will not be available.
If a fault is undetected, the gear lever position is likely to be interpreted as being higher than actual. Where Park is the
highest position and Manual 1 is the lowest, the result being the availability of higher gears than selected by the gear
lever.