The TAAT is equipped with 5 solenoids called actuators.
These transaxle control actuators are electrohydraulic
solenoid valves consisting of a housing, valvebody, sliding
armature and a electromagnetic coil. They are a three port
design with a pressure supply port, a pressure outlet or
control pressure port, and an exhaust port (See Figure 5).
The actuators have normally applied valves. When no
voltage is applied to the terminals, a return spring holds the
valve open and the actuator will allow oil to flow from the
supply port to the outlet pressure port. When current flows
through the coil, the magnetic field is energized pulling the
sliding armature against the return spring. When the
armature is in this position, the valve is closed, the pressure
port is blocked, and the outlet port is connected to the
exhaust port.
These 5 actuators are located in the transaxle mounted on
top of the valvebody (See Figure 6). Each actuator may be
completely energized (closed), de-energized (open), or
pulse width modulated (PWM). Figure 7 shows a basic
solenoid application chart illustrating both closed, open
and pulsed width modulated states. When an actuator is
being modulated, the valve opens and closes up to 70 times
per second. This allows a percentage of oil pressure
available at the supply port to pass to the outlet port. The
actual percentage time the actuator is pulsed, is determined
by an electrically controlled duty cycle from the PCM.
This is the ratio of the length of time the valve remains
open (pulse width) to the total length of time of each cycle
(one on and off cycle).
ACTUATORS:
GEAR TEETH COUNTS AND RATIOS
All SOHC engines use MP6 Transaxles
All DOHC engines use MP7 Transaxles
1993
2nd Design**
MP6 Base
91-93
1st Design*
MP6 Base
91-93
MP7
Performance
GEAR
1st Drive
1st Driven
2nd Drive
2nd Driven
3rd Drive
3rd Driven
4th Drive
4th Driven
Rev Drive
Rev Driven
Rev Idler
Final Drive
Output Shaft
Ring Gear
21
47
30
38
37
30
42
25
21
40
27
27
15
62
19
48
30
38
37
30
42
25
21
40
27
27
15
62
19
48
27
42
33
34
40
28
21
40
27
27
15
62
GEAR RATIO
GEAR
1st Gear
2nd Gear
3rd Gear
4th Gear
Reverse
Final Drive
2.53
1.56
1.03
0.70
2.39
4.1333
2.53
1.17
0.81
0.60
2.39
4.1333
2.24
1.17
0.81
0.60
2.39
4.1333
* Vehicles built prior to, and including VIN PZ156139
** Vehicles built after, and including VIN PZ156140
NOTE: An updated ratio chart can be
found on page 114
Figure 4
PRESSURE
SUPPLY PORT
PRESSURE
OUTLET PORT
EXHAUST PORT
Figure 5
7
AUTOMATIC TRANSMISSION SERVICE GROUP
Technical Service Information