TM 5-3805-290-23-1
THEORY OF OPERATION - CONTINUED
0003 00
TRANSMISSION - CONTINUED
N OT E
Because two input lines are used for each direction, ECM can diagnose problems with circuits for direction
lever. A solenoid for direction is not activated and transmission remains in neutral if the following actions
occur:
a.
Direction Switches. In normal operation, switches for transmission direction and shift lever
close direction inputs on ECM to ground. Closed switches tell ECM direction that is selected
by operator. ECM then activates appropriate directional solenoid. Direction lever does not
ground either of forward or reverse ECM inputs. Direction lever grounds both reverse and
forward input at the same time.
Speed Switches. In normal operation, switches for speed close speed inputs on ECM to
b.
ground. Closed switches tell ECM speed selected by operator. ECM then activates
appropriate solenoid for the selected speed.
Transmission Neutralizer Override Switch. When this switch is activated, transmission neutralizer over-
(5)
ride switch opens neutralizer input line of transmission ECM regardless of brake position. This switch is
used to disable neutralizer switch when neutralizing transmission during braking is not desired.
N OT E
A double-pole, single-throw switch is used for diagnostic purposes. If two poles are ever tied to +battery
voltage, control knows that a circuit failure is present. This fault is then shown on diagnostic indicator.
Ride Control Switch. Ride control switch signals mode selected by operator to ECM. Operator may select
(6)
AUTO, ON, or OFF modes.
(7)
Parking Brake Switch. Parking brake switch is used to signal status of parking brake to ECM. If parking
brake is applied and machine is in gear, machine remains in NEUTRAL. If machine is shifted into gear and
parking brake is applied, machine will stay in NEUTRAL. When parking brake is applied and machine
speed is above a preset speed, transmission will automatically downshift to slow machine.
Data Link. Machine ECM uses input from diagnostic connector via CAT data link. Machine ECM also uses input
b.
from engine ECM via CAN data link.
c.
Speed Sensors. All speed sensors are located on right side of transmission case. As gear teeth pass end of each sen-
sor, an ac voltage is produced. Frequency of voltage is proportional to gear teeth speed. ECM uses these signals
from these sensors to make decisions:
(1)
Torque converter output speed sensor
(2)
Intermediate speed sensors
(3)
Output speed sensors
0003 00-42
