Service manual

Electrical Service Manual V4.0
1
1-5
CENTRAL COMMAND I
THROTTLE SIGNAL
The throttle signal originates at the high and low throttle signal outputs of the Curtis Control.
The high and low output are sent to the coil circuit of a 5K ohm hermetically sealed poten-
tiometer. The potentiometer sums the signals and outputs a varied voltage signal from 0.2
volts (+/- 0.2 volts) to 4.8 volts (+/- 0.2 Volts) on the center terminal of the potentiometer.
Walk Behinds
The signal that comes out of the potentiometer is then sent to the common terminal on one
pole of a double pole double throw toggle switch. The terminal from on of the throws is then
wired to the throttle input of the controller.
On the same terminals of the switch that have the potentiometer output wire and the wire
that runs back to the controller there is an additional wire piggybacked in each terminal.
These wires go to the handle bar buttons. When either one of the handle bar buttons is de-
pressed or the reverse switch is depressed the varied voltage signal from the potentiometer
passes through the switch and then through the wire to the controller.
Riders
The signal that comes out of the potentiometer is then sent to the throttle input signal on the
controller.
The controller then calculates the voltage being sent by the potentiometer and adjusts the
machine’s travel speed accordingly.
On some walk-behinds, due to the way we interrupt the throttle signal to start and stop the
machine, the Curtis Controllers will flash a Diagnostic Flash Code of “1-2” when the throttle
is not depressed. This indicates there is an open circuit in the throttle circuit.
CURTIS SELF TESTS
When the throttle input moves above 0.2 Volts the Curtis Control turns on and immediately
checks the following.
#1 Relay coil circuit test – This test measures the resistance of the coil circuit on the #1 relay.
The relay coil circuit test must have a value of between 68 and 78 ohms or the controller will
not start.
#1 Relay contact test – This test checks to make sure there is no continuity from one side of
the relay’s contact to the other. This ensures that the relay is in an open state before apply-
ing power to it.
#2 Relay coil circuit test - This test measures the resistance of the coil circuit on the #2 relay.
The relay coil circuit test must have a value between 68 and 78 ohms or the controller will
not start.