Webasto Product N.A., Inc. 38 www.techwebasto.com
CIRCUIT DIAGRAMS DBW 2010/2020/300 COOLANT HEATERS
7.4 DBW 2020 / 300 12 V AND 24 V - WITH NOZZLE PREHEAT
Figure 29: Schematic - DBW 2020 / 300 With Nozzle Preheat
BT BATTERY
DS INDICATOR LIGHT
E IGNITION ELECTRODES
F1 FUSE 15A
F2 FUSE 20A
F3 FUSE 15A
F4 OVERHEAT FUSE 138°C
F5 FUSE 30A
F6 FUSE 15A
HR HEATING ELEMENT (fuel pre-heater)
K1 RELAY (on / off switch)
K2 RELAY (fuel pre-heater)
L1 SOLENOID VALVE
L2 IGNITION COIL
M1 COOLANT CIRCULATION PUMP
M2 HEATER MOTOR
R FLAME DETECTOR
S1 ON / OFF SWITCH (heater)
S2 PREHEAT (FUEL) THERMOSTAT
(blue and blue wires)
S3 CONTROL THERMOSTAT
(green and red wires)
S4 TEMPERATURE LIMITER
(green and green wires)
X1 9-PIN HARNESS CONNECTOR (round)
X2 3-WAY CONNECTOR
X3 2-WAY CONNECTOR
BROWN
BROWN
BROWN
REDRED
RED
BT
E
F
G
J
C
B
A
S1
DS
F5
X1
H
WHITE
GREEN
RED
BLACK
WHITE
WHITE
WHITE
VIOLET
F4
t°
t° t°
WHITE
WHITE
BLACK
BLUE
VIOLET
GREEN
GREEN
GREEN
RED
ORANGE
WHITE
BROWN
BLACK
BLUE
GREEN
YELLOW
BROWN
BROWN
BROWN
BLUE
BLUE
BLACK
BLACK
GREEN
BROWN
ORANGE
GREEN
BROWN
BROWN
BROWN
BROWN
BROWN
BROWN
BROWN
RED
RED
BROWN
L1
R
L2
E
S4S3
M2
HR
S2
K2
M1
A
B
C
C
A
B
M
1
2
4
1
3
6
5
2
52 17
4
68
65
3
4
2
1
85
86
87
30
+
–
CONTROL UNIT
HEATER
1 2
3
45
62
1
1 2
3
4
5
6
7
8
BLACK
BROWN
M
BLUE
BLACK
GREEN
2
1
3
K1
85
86
87
30
X2
F1
F2
F3
E
F CDAB
RED
BLUE
ORANGE
GREEN
RED
RED
F6
A
B
ORANGE
WHITE
WHITE
D
X3
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