World Transmission (Wt) Electronic Controls(For Automatic Transmission With Push Button Shift Selector); Jacobs Engine Brake - PREVOST H3-41 Manual

WORLD TRANSMISSION (WT)
ELECTRONIC CONTROLS
(For Automatic Transmission
with Push-Button Shift Selector)
The World Transmission (WT) electronic controls
comprises four major elements:
Control Unit (ECU), Throttle Position Sensor
(TPS), speed sensors, and shift selector. Refer to
"Controls & Instruments"
components work together to electronically control
the transmission functions. The throttle sensor,
speed sensors, and shift selector transmit
information to the ECU. The ECU processes this
information and then sends signals to actuate
specific solenoids located on the control valve
body in the transmission.
solenoids affects hydraulic circuits, which in turn
control the upshifts, downshifts, and lock-up
functions. In addition to controlling the operation
of the transmission, the WT electronic controls
monitor the system for abnormal conditions.
When one of these conditions is detected, WT
electronic control system is programmed to
automatically respond in a manner which is safe
for the driver, the vehicle, and the transmission.
The WT electronic control system turns on the DO
NOT SHIFT light on the central dashboard which
serves as a fault indicator.
To enhance troubleshooting, and to allow
interrogation of the ECU (Electronic Control Unit)
for valuable service information, the shift selector
display or a diagnostic tool (not supplied) by the
manufacturer) can be used.
about reading and interpreting diagnostic codes,
refer to "Technical Information" section under
"World Transmission (WT) Diagnostic Codes".
Electronic
section. These
The action of the
For information
4-6

JACOBS ENGINE BRAKE

The Jacobs engine brake is a diesel engine
retarder that uses engine compression to aid in
slowing and controlling the coach.
activated, (refer to "Controls & Instruments"
section) the Jacobs brake alters the operation of
the engine's exhaust valves so that the engine
works as a power-absorbing air compressor. This
provides a retarding action to the wheels.
The engine brake is a vehicle-slowing device, not
a vehicle-stopping device. It is not a substitute for
the service braking system. The coach's service
brakes must be used to bring the coach to a
complete stop.
Effectiveness of the engine brake system will vary
according to the transmission range in use. The
engine brake system is more effective in lower
ranges and at higher engine speeds.
WARNING: WHEN
SIGNIFICANT GRADES,
BRAKES AS LITTLE AS POSSIBLE. IF ENGINE
DOES NOT SLOW COACH TO A SAFE SPEED,
APPLY SERVICE BRAKES AND SHIFT TO A
LOWER RANGE. LET THE ENGINE (AND
ENGINE BRAKE) SLOW THE COACH. KEEP
BRAKES COOL
EMERGENCY STOPPING.
NOTE: Each time the engine brake system is in
operation, the stoplights
illuminate.
OTHER FEATURES
When
DESCENDING
USE SERVICE
AND READY FOR
will automatically