Subaru 2002 Impreza Service Manual page 250

TRANSMISSION CONTROL MODULE (TCM)
Automatic Transmission
6. ABS CONTROL
When the TCM receives an ABS operation signal from the ABS unit, it adjusts the differential action
limiting torque to the predetermined level and selects the 3rd gear in which the one-way clutch
is freewheeling.
This function improves ABS control.
7. BASE BRAKE CONTROL
When the brake switch is ON and the throttle valve is fully closed, the TCM makes control to de-
crease the differential action limiting torque. The ABS control has priority over this control.
This function improves stability during braking.
8. 1 RANGE CONTROL
When the 1 range is selected, the TCM makes control to increase the differential action limiting
torque.
This function improves driving performance and traction.
9. CONTROL SYSTEM
The TCM is constantly monitoring the driving conditions of the vehicle using the eleven input sig-
nals. Based on the conditions it has determined, the TCM adjusts the duty ratio of current to the
transfer duty solenoid thus changing the engagement of the multi-plate clutch. The input signals
are used also for automatic transmission control.
Sensor TCM
I
Input
interface
circuit
!
'
Throttle position sensor
1 ' I 1 I
N D
+
converter
e
7 1
ATF temperature sensor
I !
*u u
L ' ! I
' I
(rear wheel rpm)
Front vehicle speed sensor
(front wheel rpm)
b
b
Brake switch
ABS signal
b
Input
interface
circuit
r
cz
CPU
A
v
t
Constant
voltage source
1
Output interface
I -
circuit
i
----
Actuator
i
solenoid
L-
Multi-plate
NF0493
AT-28