
37
24 - Electrical System
Understanding the Features of the Main Wiring Diagram
The main wiring diagram is sometimes referred to as a ladder diagram because it is historically rooted
in a type of schematic that resembled the rungs of a ladder Over time it has evolved into a hybrid ladder
diagram, specifically to accommodate the presence
of intelligent control modules that drive the system
components (Such as a main controller and power module,
for example ) Even as a hybrid diagram, it still maintains
some of the features of a true ladder diagram
Positive voltage source(s) are represented by vertical
“Rails” on the left side of the diagram, and the negative
voltages source (typically only 1, being battery negative)
is represented by a vertical Rail on the right side of the
diagram Devices are drawn between the two rails, and
current flows from the positive rail, through the load, and to
the negative rail
Unique to the hybrid ladder diagram are the intelligent
controllers that control if and when devices are connected
to either positive or negative power Even though not
technically accurate, circuit symbols have been drawn
inside the controller outlines to represent the electrical
function that takes place inside These represent the
function, but not an actual device For example, even though a symbol may look like a switch, it cannot be
tested as though it was a real switch
Some of the common controller internal symbols are described below:
B-
Output, Switch to positive or negative power.
The controller serves to complete the circuit to the respective power source, most
commonly battery negative.
B-
B+
Output, Bi-directional switch to power
These outputs are always in pairs, and are for reversible loads.
•
For forward direction, one output is positive and the other is negative.
•
For reverse direction, one output is negative and the other is positive.
•
For no movement, both outputs are the same, which may be positive, negative,
or zero, depending on the controller.
PWM
B-
Pulse Width Modulation (PWM) Switch
This is an electronic (transistor) switch that completes the circuit to either battery
positive or battery negative power. The duty cycle between on and off states
determines how much power the load receives.
SCLK
Digital Data Out
This symbol indicates that the output is a digital stream of data pulses.
+3.3V
Digital Data In, with Pullup
This symbol represents a digital data stream input signal that is active-low, and the
pullup resistor represents the open-circuit (inactive) signal voltage.
+5V
Discrete Input with Pullup
This symbol represents a binary (On/Off) input with a 5-volt pullup resistor. When
the switch or sensor is off (open circuit) the pullup resistor makes the input equal 5
volts. When the switch or sensor is closed, the input typically goes to 0 volts.
B-
J4-10
B+
J4-19
CURTIS 1229
DRIVE WHEEL CONTROLLER
J4-14
J4-1
J4-2
J4-17
J4-16
J4-4
J4-3
J4-20
KSI
J4-13
J4-11
J4-18
J4-6
J4-9
J4-12
M1
M2
M1
ORN
BLU/VIO
RED/GRN
YEL/BLK
YEL/WHT
GRN/ORN
VIO/BLK
BLK/WHT
BLU/BLK
GRN/GRY
BLK
YEL
GRN
POT 1
POT 2
J4-8
(V) TO 2A1
(W) TO 4A3
(B) TO 2A1
(C) TO 4A4
(AA) TO 1B2
(AB) TO 1B2
(AC) TO 4B3
(AD) TO 5B4
(AF) TO 2E1
(AG) TO 4E4
ANALOG GND
DRIVER 1
DRIVER 2
SWITCH 1
SWITCH 2
SWITCH 3
SWITCH 4
A3
BLU/RED
RED
RED
YEL/BLU
BLK
GRN/BLU
GRY
ORN/GRN
GRY
GRY
GRN
YEL
B+
STEERING READY
AUTO OK
KSI
B-
OPERATOR PRESENCE SW
E-STOP MAIN CONTROL BOARD
CAN1 L, (R) TO 2D2
CAN1 H, (Q) TO 2D3
CAN1 L, (T) TO 4A2
CAN1 H, (S) TO 4A2
B+
KSI
B-
B-
B-
+5V
F6
FUSE, 40 A.
1
2
K3
3
4
1
2
B-
B-
B+
+17V
SW14
X1
1
2
3
4
B-
B+
B-
Y1
EM BRAKE
1
2
R1
C
B
A
M
-
+
Sample