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EngineAJ-V8/5HP24
30
Operating Modes (Refer to the figure, page 31)
Normal
1. Throttle cable inputs driver demand
2. Input shaft turns mechanical guard
3. Sensors supply ECM with inputs of driver demand
4. ECM operates dc motor
5. Sensor supplies ECM with inputs of throttle valve position
6. Gap maintained between throttle valve and mechanical guard
Cruise Control
1. Vacuum actuator turns mechanical guard
2. Sensor supplies ECM with mechanical guard position
3. ECM operates dc motor
4. Sensor supplies ECM with inputs of throttle valve position
5. Gap maintained between throttle valve and mechanical guard
6. Input shaft at idle position, disengaged from mechanical guard
Mechanical Guard
1. Throttle cable inputs driver demand
2. Input shaft turns mechanical guard
3. Mechanical guard turns throttle valve
4. dc motor drive disengaged from throttle valve
At idle, the ECM controls engine speed using the
restricted throttle valve movement available
between the mechanical guard (open limit) and a
factory set stop on the dc motor drive gear
(closed limit).
When cruise control is engaged, the ECM
calculates the required throttle valve opening and
operates the vacuum system connected to the
vacuum actuator. The vacuum actuator then turns
the mechanical guard to a position that allows the
required throttle valve opening. The inputs from
their respective position sensors allow the ECM
to monitor and adjust the mechanical guard and
the throttle valve to maintain the set speed. As
the driver releases the accelerator pedal, the
input shaft disengages from the mechanical
guard. Note that during cruise control, when
accelerating above the set speed, the accelerator
pedal has a lighter "feel" until the input shaft
engages with the mechanical guard again.
Mechanical operation of the throttle valve occurs
if the ECM selects the mechanical guard mode of
operation after detecting a fault. The ECM de-
energizes the dc motor and the throttle valve
spring turns the throttle valve in the open
direction until it engages the mechanical guard.
The input shaft, mechanical guard and throttle
valve are then effectively locked together by their
springs, so that the throttle cable is in direct
control of the throttle valve. When the throttle
valve opens, it turns the dc motor drive gears. On
subsequent closing of the throttle valve the drive
gears remain in the open position, disengaged
from the throttle valve.