SENR6127
November 1993
312 Excavator
Electrical System
6BL1-UP
B
2
3
3
1
2
3
5
B
1
2
4
1
1
2
3
4
AREA E
AREA F
A
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
3
4
5
6
8
9
10
11
12
14
15
11
16
B
C
D
E
1
2
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
7
F
6
30
17
18
19
20
21
22
23
24
25
29
10
9
A
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
3
4
5
8
9
10
11
12
14
15
13
16
B
C
D
E
1
2
17
18
19
20
21
22
23
24
25
26
27
28
29
30
32
33
34
7
F
17
18
19
20
21
22
23
24
25
N
MACHINE HARNESS CONECTOR AND COMPONENT LOCATIONS
1
2
3
4
3
4
D
E
1
2
F
A
1
2
3
4
5
6
3
4
5
6
G
H
1
2
7
A
AREA A
AREA B
A
1
2
3
A
K
1
2
A
1
2
3
4
5
6
7
8
3
4
5
6
8
9
KK
L
HH
B
1
2
7
B
AREA C
AREA D
Component Location
Machine
Location
Component
Schematic
Location
Machine
Location
Component
Schematic
Location
1
Actuator - Governor A-12
7D
Relay - Washer E-8
3A
Alarm - Action D-2
7D
Relay - Wiper E-8
2
Alarm - Travel D-11
1C
Resistor - Backup E-5
3
Alterator B-12
8D
Resistor - Air Heater D-8
4
Antenna C-6
22
Sensor - Engine Coolant Temp B-12
5
Batteries C-9
23
Sensor - Fuel Level B-5
1D
Block - Terminal D-9
1F
Sensor - Hydraulic Oil Temp B-8
4D
Breaker D-9
24
Sensor - Speed B-10
6
Controller F-12
25
Solenoid - A/C Compressor Clutch C-12
7
Converter B-7
26
Solenoid - Engine Shutdown B-10
3B
Dial - Engine Speed C-2
5F
Solenoid - Level Finish A-8
6D
Fuse - Block F-7, 8, 9
3F
Solenoid - Travel Speed A-8
8
Heater - Air B-10
2F
Solenoid - Trenching A-8
9
Horn A-2, B-2
27
Speaker B-6
10
Lamp-Boom A-1, B-1
3E
Switch - Boom Raise Pressure B-8
11
Lamp - Cab E-1, F-1
5D
Switch - Disconnect D-9
12
Lamp - Chassis A-2
28
Switch - Engine Oil Pressure B-12
13
Lamp - Dome D-6
4B
Switch - Governor Backup C-5
1A
Lighter - Cigar E-3
3B
Switch - Horn F-3
2A
Meter - Service E-2
1E
Switch - Implement Swing Pressure C-8
4A
Monitor E-2
2B
Switch - Low Idle D-3
14
Motor - Lower Washer F-12
6B
Switch - Lower Washer B-3
15
Motor - Lower Wiper F-2
7B
Switch - Lower Wiper C-3
16
Motor - Starter A-12
29
Switch - Neutral Start F-2
17
Motor - Upper Washer F-12
2C
Switch - Pump Backup E-4
18
Motor - Upper Wiper F-2
30
Switch - Refrigerate Low Pressure B-8
19
Pump - Refueling A-3
31
Switch - Refueling A-5
20
Radio C-6
32
Switch - Refueling Pump A-3
7D
Relay - Boom Lamp E-8
5B
Switch - Speed Change B-4
7D
Relay - Chassis/Cab Lamp E-8
1B
Switch - Key Start C-2
8D
Relay - Heater D-8
15
Switch - Windshield D-2
7D
Relay - Horn E-7
2E
Switch - Travel Pressure C-8
3D
Relay - Main D-7
33
Unit - Air Conditioner D-6
7D
Relay - Refueling Pump E-7
34
Unit - Heater E-6
9D
Relay - Safety E-9
4F
Valve - Proportional Reducing A-8
2D
Relay - Start B12
A = Components in monitor panel. D = Components in relay panel.
B = Components in right console. E = Components located near control valve.
C = Components in left console. F = Components located near manifold block.
Connectors
Connector
No. And
Machine
Harness And/Or Components
Schematic
Location
Connectors
Connector
No. And
Machine
Location
Harness And/Or Components
Schematic
Location
40 Contacts
CONN1
*
A - 113-1159
Controller
D-12
CONN25
A - 113-1159
G - 113-7621
D-3
24 Contacts
CONN2
*
A - 113-1159
Controller
F-12
CONN60
A - 113-1159
G - 113-7621
D-3
CONN9
A - 113-1159
B-110-2546
D-11
CONN23
A - 113-1159
J - 7Y-3868
F-3
CONN8
A - 113-1159
B-110-2546
D-10
CONN39
A - 113-1159
Refrigerate Switch
D-12
CONN13
A - 113-1159
F - 6C-9361
C-5
CONN45
A - 113-1159
Travel Alarm
D-11
CONN24
A - 113-1159
G -113-7621
D-3
CONN50
B - 110-2546
Boom Raise Pressure Sw
B-8
CONN18
A - 113-1159
H - 41-5463
D-4
CONN49
B - 110-2546
Fuel Level Sensor
B-5
CONN17
A - 113-1159
K - 4I-5411
E-5
CONN51
B - 110-2546
Implement Swing PressureSw
C-8
CONN3
A - 113-1159
L - 105-9958
E-9
CONN53
B - 110-2546
Level Finish Solenoid
A-8
CONN5
A - 113-1159
L - 105-9958
F-9
CONN38
B - 110-2546
N - 4I-5460
B-2
CONN6
A - 113-1159
L - 105-9958
F-9
CONN48
B - 110-2546
PP - 5I-8358
A-6
CONN4
B - 110-2546
L - 105-9958
E-9
CONN56
B - 110-2546
Proportional Reducing Valve
A-8
9 Contacts
CONN57
C - 7Y-8139
Radio
C-6
CONN41
B - 110-2546
Refueling_Pump
A-3
7 Contacts
CONN14
A - 113-1159
E - 6C-9117
C-5
CONN34
B - 110-2546
Refueling Pump Sw
A-3
CONN10
A - 113-1159
B - 110-2546
D-10
CONN42
B - 110-2546
Speed_Sensor
B-10
CONN11
B - 110-2546
Safety Relay
E-9
CONN52
B - 110-2546
Travel Press Sw
C-8
CONN28
F - 6C-9361
Z - 6C-9362
E-2
CONN58
B - 110-2546
Travel Speed Solenoid
A-8
CONN15
A - 113-1159
A/C Unit
D-6
CONN54
B - 110-2546
Trenching Solenoid
A-8
CONN19
A - 113-1159
H - 4I-5463
D-4
CONN63
??
E - 6C-9117
F - 6C-9361
D-2
CONN15
A - 113-1159
Heater Unit
E-6
CONN31
E - 6C-9117
Action Alarm
D-2
CONN44
B - 110-2546
Governor Actuator
A-11
CONN61
G - 113-7621
Air Heater Sw
C-2
CONN27
G - 113-7621
Engine Speed Dial
C-2
CONN26
G - 113-7621
Low Idle Sw
D-3
CONN58
A - 113-1159
A - 113-1159
D-12
CONN22
H - 4I-5643
Lower Washer Sw
B-3
CONN62
A - 113-1159
Not Used
E-2
CONN20
J - 7Y-3868
Horn Sw
F-3
CONN33
Z - 6C-9362
Lower Wiper Motor
F-2
CONN7
R - 7Y-8105
Converter
B-7
CONN12
C - 7Y-8139
F - 6C-9361
C-6
CONN37
B - 110-2546
A/C Clutch Solenoid
E-1
CONN30
E - 6C-9117
Monitor
E-2
CONN59
S - 113-0506
Eng Shutdown Solenoid
A-10
CONN36
F - 6C-9361
Y - 6C-8839
E-1
CONN32
F - 6C-9361
Upper Wiper Motor
F-2
CONN12
F - 6C-9361
R - 7Y-8105
C-7
CONN43
C - 7Y-8139
Speaker
B-6
CONN21
H - 4I-5463
Lower Wiper Switch
C-3
CONN29
R - 7Y-8105
Converter
B-7
* = Connectors located in controller compartment. C = Connectors located in operator’s left console.
A = Connnectors located in lower cab. D = Connectors located in relay panel.
B = Connectors located in operator’s right console. E = Connectors located near pilot manifold.
HARNESS CONNECTOR LOCATION CHART
3 Contacts
2 Contacts
10 Contacts
6 Contacts
5 Contacts
4 Contacts
T
Normally open switch that will close with an increase of a specific condition (temp-press-etc.).
Normally open switch that is closed due to an applied condition, and will open again with a
specific decrease in that condition.
Normally closed switch that will open with an increase of a specific condition.
Normally closed switch that is open due to an applied condition, and will close again
with a specific decrease in that condition.
The circle indicates that the component has screw terminals and a wire can be disconnected
from it.
No circle indicates that the wire cannot be disconnected from the component.
This indicates that the component has a wire connected to it that is connected to ground.
This indicates that the component does not have a wire connected to ground. It is grounded
by being fastened to the machine.
Electrical Schematic Symbols And Definitions
Pressure
Symbol
Temperature
Symbol
Level
Symbol
Flow
Symbol
A AA
2
A AA
1
2
325-PK-14
C
A
325-PK-14
200-BK-14
T
FUSE - A component in an electrical circuit that will open the circuit if too much current flows
through it.
REED SWITCH - A switch whose contacts are controlled by a magnet. A magnet closes the
contacts of a normally open reed switch; it opens the contacts of a normally closed reed switch.
SENDER - A component that is used with a temperature or pressure gauge. The sender
measures the temperature or pressure. Its resistance changes to give an indication to the
gauge of the temperature or pressure.
RELAY (Magnetic Switch) - A relay is an electrical component that is activated by electricity.
It has a coil that makes an electromagnet when current flows through it. The electromagnet
can open or close the switch part of the relay.
CIRCUIT BREAKER (C/B) - A component in an electrical circuit that will open the circuit if too
much current flows through it. This does not destroy the circuit breaker and it can be reset to
become part of the circuit again.
SOLENOID - A solenoid is an electrical component that is activated by electricity. It has a coil
that makes an electromagnet when current flows through it. The electromagnet can open or
close a valve or move a piece of metal that can do work.
Harness And Wire Electrical Schematic Symbols
Socket
Pin
Pin or Socket
Number
Wire, Cable, or Harness
Assembly Identification
Single Wire
Connector
Circuit Number
Identification
Wire
Gauge
Wire
Color
Plug
Receptacle
9X-1123
Component
Part Number
Electrical Schematic Symbols And Definitions
1
1
1
2
2
Typical representation of a
Sure-Seal connector. The
plugand receptacle contain
both pins and sockets.
Typical representation of a
Deutsch connector. The
plug contains all sockets
and the receptacle contains
all pins.
MAGNETIC LATCH SOLENOID - A magnetic latch solenoid is an electrical component that is
activated by electricity and held latch by a permanent magnet. It has two coils (latch and unlatch)
that make electromagnet when current flows through them. It also has an internal switch that places
the latch coil circuit open at the time the coil latches.
©
1993 Caterpillar
All Rights Reserved
Printed in U.S.A.
L6
210-BK
135-BU
200-BK
120-YL
2
4
1
3
365-YL
325-PK
200-BK
323-WH
200-BK
607-PK
616-BU
322-GY
200-BK
235-BK
200-BK
200-BK
607-PK
200-BK
323-WH
200-BK
365-YL
325-PK
200-BK
200-BK
113-OR
B751-YL
513-OR
A763-GY
A768-BU
A769-GY
309-GY
403-GN
323-WH
365-YL
327-PK-10
101-RD-4
109-OR-6
616-BU
877-YL-4
607-PK
142-BU-14
200-BK
D746-PK
309-GY
403-GN
D746-PK
309-GY
403-GN
403-GN
309-GY
A769-GY
A768-BU
A763-GY
513-OR
B751-YL
D764-GN
B965-GY
B964-YL
B737-GN
A771-PU
113-OR
D746-PK
A762-PU
A761-PU
788-YL
763-BU
495-GN
492-GY
BK-00200-BK
200-BK
267-BK
266-BK
235-BK
235-BK
308-YL
310-PU
105-BR
120-YL
185-YL-14
129-BU
124-GN-14
320-OR
500-BR
501-GN
103-YL
118-GY
152-BU
615-YL
113-OR
A768-BU
B731-WH
B730-OR
B740-OR
B739-WH
B790-OR
B789-BR
B955-YL
B956-PK
B786-BU
A755-PK
A756-BU
A757-GY
A758-BR
410-WH
308-YL
578-BU
519-PK
513-OR
513-OR
519-PK
578-BU
308-YL
410-WH
A758-BR
A757-GY
A756-BU
A755-PK
B786-BU
B956-PK
B955-YL
B789-BR
B790-OR
B739-WH
B740-OR
B730-OR
B731-WH
A768-BU
235-BK
235-BK
266-BK
267-BK
200-BK
200-BK
D764-GN
D746-PK
A762-PU
788-YL
405-GY
492-GY
A761-PU
495-GN
763-BU
B964-YL
B965-GY
B737-GN
A771-PU
491-PK
506-PU
332-BU
786-GN
121-YL
791-PK
792-OR
A983-BU
184-BU
877-YL
519-PK
513-OR
321-BR
121-YL
121-YL
321-BR
513-OR
519-PK
321-BR
121-YL
519-PK
513-OR
235-BK
267-BK
786-GN
308-YL
410-WH
A758-BR
A757-GY
A756-BU
A755-PK
B786-BU
B956-PK
B955-YL
B789-BR
B790-OR
B739-WH
B740-OR
B730-OR
B731-WH
A768-BU
877-YL
184-BU
A983-BU
792-OR
791-PK
491-PK
A771-PU
B737-GN
B965-GY
B964-YL
763-BU
495-GN
491-PK
405-GY
124-GN-14
519-PK
615-YL
103-YL
200-BK-14
266-BK
578-BU
200-BK
200-BK
506-PU
332-BU
321-BR
D764-GN
D746-PK
A762-PU
788-YL
405-GY
492-GY
A761-PU
495-GN
791-PK
792-OR
A983-BU
184-BU
877-YL
A768-BU
B731-WH
B730-OR
B740-OR
B739-WH
B790-OR
B789-BR
B955-YL
266-BK
267-BK267-BK
266-BK
265-BK
264-BK
235-BK
763-BU
B956-PK
B964-YL
B786-BU
B965-GY
B737-GN
A771-PU
491-PK
A755-PK
A756-BU
A757-GY
A758-BR
410-WH
308-YL
786-GN
235-BK
RD-00
RD-00
235-BK
513-OR
D746-PK
109-OR-6
403-GN
309-GY
200-BK-6
492-GY
405-GY
101-RD-4
101-RD-4
405-GY
492-GY
200-BK-6
309-GY
403-GN
109-OR-6
D746-PK
513-OR
877-YL-4
A762-PU
788-YL
327-PK-10
200-BK
200-BK
200-BK
200-BK-6
113-OR
200-BK
A761-PU
A763-GY
B751-YL
RD-00
RD-00
101-RD-4
405-GY
492-GY
200-BK
200-BK
200-BK-6
309-GY
403-GN
109-OR-6
200-BK
200-BK
513-OR
B751-YL
A763-GY
A761-PU
200-BK
113-OR
200-BK-6
200-BK
200-BK
200-BK
327-PK-10
327-PK-10
788-YL
A762-PU
877-YL-4
877-YL-4
B737-GN
D764-GN
200-BK
A771-PU
491-PK
B964-YL
B965-GY
763-BU
A768-BU
A769-GY
101-RD-14
112-PU-14
112-PU-14
112-PU-14
308-YL
320-OR
152-BU
103-YL
152-BU
118-GY
121-YL
184-BU
103-YL
114-GN
120-YL
113-OR
500-BR
118-GY
501-GN
615-YL
BK-00
149-PU
120-YL
113-OR
115-PK
142-BU-14
615-YL
501-GN
118-GY
500-BR
113-OR
184-BU
786-GN
332-BU
506-PU
121-YL
792-OR
791-PK
A983-BU
877-YL
616-BU
607-PK
323-WH
365-YL
322-GY
101-RD-14
112-PU-14
112-PU-14
112-PU-14
112-PU-14
112-PU-14
200-BK
200-BK
BK-00
BK-00
200-BK 101-RD-4 877-YL
877-YL-4
109-OR-10
109-OR-6
200-BK
112-PU-14
112-PU-14
112-PU-14
112-PU-14
BK
RD
877-YL
A983-BU
791-PK
792-OR
121-YL
506-PU
332-BU
786-GN
184-BU
113-OR
615-YL
152-BU
118-GY
103-YL
501-GN
500-BR
320-OR
124-GN-14
129-BU
185-YL-14
D746-PK
D746-PK
200-BK
330-YL
309-GY
309-GY
403-GN
403-GN
WH/YL
BK
WH/BU
YL
WH/GN
101-RD-6
101-RD-14
101-RD-14
120-YL
105-BR
310-PU
308-YL
323-WH
365-YL
168-GN149-PU 616-BU
786-GN
607-PK
120-YL
615-YL115-PK
114-GN 322-GY
320-OR
506-PU
A983-BU
118-GY
118-GY
501-GN
501-GN
501-GN
118-GY
792-OR
500-BR
118-GY
BK-00
BK-00 BK-00
365-YL
323-WH
607-PK
322-GY
616-BU
200-BK
491-PK
A769-GY
B964-YL
200-BK
A768-BU
B965-GY
A768-BU
A769-GY
763-BU
B965-GY
495-GN
A769-GY
A768-BU
B965-GY
142-BU
142-BU
B964-YL
142-BU
491-PK
200-BK
B964-YL
491-PK
200-BK
A771-PU
200-BK
D764-GN
B737-GN
200-BK
D764-GN
A771-PU
200-BK
200-BK
B737-GN
200-BK
200-BK
124-GN-14
519-PK
103-YL
615-YL
615-YL
103-YL
120-YL
500-BR
501-GN
118-GY
113-OR
129-BU
403-GN
410-WH
B955-YL
B956-PK
B731-WH
B730-OR
A769-GY
A768-BU
185-YL
185-YL
152-BU
A763-GY
B751-YL
B739-WH
B789-BR
B740-OR
B790-OR
578-BU
B786-BU
309-GY
308-YL
310-PU
105-BR
A758-BR
A757-GY
A756-BU
A755-PK
320-OR
306-GN
200-BK-14
103-YL
615-YL
519-PK
124-GN-14
200-BK
103-YL
200-BK
B740-OR
185-YL
B789-BR
B739-WH
B790-OR
B751-YL
578-BU
152-BU
152-BU
575-YL
576-PK
200-BK
200-BK
200-BK
200-BK
200-BK-14
GN
GY
235-BK
235-BK
200-BK
616-BU
322-GY
607-PK
323-WH
365-YL
325-PK
325-PK
325-PK
325-PK
325-PK
365-YL
118-GY
501-GN
500-BR
615-YL
200-BK
200-BK
200-BK
B956-PK
B955-YL
410-WH
403-GN
129-BU
113-OR
118-GY
501-GN
500-BR
615-YL
103-YL
120-YL
200-BK
200-BK
200-BK
763-BU
763-BU
578-BU
152-BU
575-YL
152-BU
576-PK
B789-BR
B739-WH
B790-OR
B740-OR
200-BK
185-YL
B751-YL
B789-BR
B789-BR
B739-WH
B790-OR
B790-OR
B740-OR
B751-YL
A763-GY
200-BK
185-YL
B790-OR
B790-OR
B789-BR
B790-OR
410-WH
113-OR
200-BK
403-GN
B956-PK
B955-YL
129-BU
129-BU
200-BK
200-BK
320-OR
576-PK
152-BU
575-YL
307-OR
306-GN
307-OR
306-GN
200-BK
575-YL
152-BU
576-PK
320-OR
200-BK
306-GN
307-OR
200-BK
B786-BU
308-YL
310-PU
105-BR
309-GY
A758-BR
A757-GY
A756-BU
A755-PK
307-OR
200-BK
410-WH
113-OR
200-BK
403-GN
201-BK
113-OR
B956-PK
B955-YL
495-GN
200-BK
575-YL
152-BU
576-PK
616-BU
200-BK
200-BK
200-BK
200-BK
200-BK
235-BK
200-BK
200-BK
200-BK
322-GY
322-GY
200-BK
322-GY
200-BK
607-PK
200-BK
616-BU
200-BK
200-BK
616-BU
616-BU
200-BK
235-BK
200-BK
322-GY
616-BU
578-BU
152-BU
322-GY
A761-PU
492-GY
405-GY
788-YL
A762-PU
D746-PK
D764-GN
321-BR
332-BU
506-PU
200-BK
200-BK
578-BU
495-GN
616-BU
322-GY
607-PK
323-WH
365-YL
615-YL
112-PU-14
327-PK-10
877-YL-4
101-RD-4
142-BU-14
322-GY
365-YL
323-WH
607-PK
616-BU
101-RD-6
109-OR-6
109-OR-6
124-GN-14
129-BU
185-YL-14
168-GN
105-BR
308-YL
B737-GN
200-BK
A763-GY
D764-GN
200-BK
A771-PU
B789-BR
142-BU-14
A770-PK
A763-GY
A770-PK
B730-OR
200-BK
323-WH
B789-BR
615-YL
120-YL
103-YL
200-BK
511-BR
512-GN
200-BK
200-BK
200-BK
200-BK
200-BK
365-YL
B786-BU
200-BK
615-YL
501-GN
200-BK
118-GY
200-BK
575-YL
152-BU
576-PK
105-BR
307-OR
308-YL
309-GY
A758-BR
A757-GY
A756-BU
A755-PK
200-BK
200-BK
F
E
D
12 11 10
C
B
A
12 11 10
9 8 7
9
8 7
6 5 4
6 5 4
3 2 1
F
E
D
185-YL
B731-WH
A769-GY
A768-BU
A769-GY
A768-BU
B731-WH
B730-OR
185-YL
200-BK
142-BU-14
142-BU-14
200-BK
3 2 1
C
B
A
200-BK
200-BK
200-BK
N
F
Y
A877-YL
N
A877-YL
1
2
A877-YL
A877-YL
G
308-YL
308-YL
R
R
R
R
ATCH CONVERTER
7T-8000
TO RADIO
ATCH
ANTENNA
7Y-3990
GROUND
+12 VOLT
+ BATTERY
GROUND
1
2
3
WH/BK-18
WH/RD-18
2
1 RD-18
BK-18
7Y-8105
HEATER UNIT
107-1995
1
2
3
4
5
B
1
2
B
B
B
P
P
N
NB
H
H
G
L3
L11
L2
L1
L3
L1
306-GN
B
START RELAY
113-2375
AIR HEATER RESISTOR
7W-1251
E
EE
E
G
G
A
A
G
G
E
L5
L2
6
7
5
4
3
2
1
FC
EF
AA
HHHH
L2
L1
L22
L11
L2
L1
L8
L10
RELAY PANEL
RELAY PANEL
RELAY PANEL
F
L10
H
A
H
A
A
K K
A
K
L4
L5
L4
L5
L9
L9
L6
L6
L8
L7
L5
L4
L12
L12
OPERATOR STATION
B B
B
B
B
B
B
B
B
L22
L22
L21
AA BB CC
FUSE
10A 9W-1442
15A 9W-1441
20A 9W-1446
SAFETY
RELAY
094-2080
DD
CC
FF
L
L
BATTERY
3T-5760
9X-3404(NOTE B)
A
JJ
L20
JJ
KK
L
L
L
L19
L19
L12
L16
L15
L14
L13
KK
LL
MM
FF
GG
LL
KK
KK
LB
B
L
B
B
B
B
A
L
LA
LA
L20
L18
L21
L21
B
B
EE
EE
B
AA
B
B
B
B
E
R
L
B
P
B
L15
L16
L16
L17L17
L17
L14
L13
L12
L12
DD
B A
AB
B A
AA
AA
A
AAAA
2
1
7
ATCH
TRAVEL
ALARM
3T-1444
ATCH
REFRIGERANT SW
(NOTE A)
A
CHASSIS
6
7
8
9
5
4
3
2
1
10
WASHER
7T-8890
ATCH
LOWER
WASHER
7T-8890
ENG PICKUP SENSOR -
ENG PICKUP SENSOR +
ENG OIL PRESS. SW
COOLANT SENSOR
GOV ACTR SENSOR
FUEL LEVEL SENSOR
TRAVEL SOLENOID
LEVEL FINISH SOLENOID
TRENCHING SOLENOID
TRAVEL SW
IMPLEMENT SW
MONITOR ALARM
THROTTLE DIAL S4
THROTTLE DIAL S3
THROTTLE DIAL S2
THROTTLE DIAL S1
LOW IDLE SW
RS485 -
RS485 +
BACKUP SW 2
BACKUP SW 1
GOV ACTR -
GOV ACTR +
EPR VALVE -
EPR VALVE +
32
22
12
33
34
21
31
15
OPTION SW 2
OPTION SW 1
OPTION SENSOR
HYD OIL LEVEL SW
ENG OIL LEVEL SW
HYD OIL TEMP SENSOR
COOLANT LEVEL SW
OPTION SOLENOID
ATTACHMENT
ENG SHUTDOWN RELAY
TRAVEL ALARM
BOOM RAISE SW
ALTERNATOR (P TERM.)
KEY SW
BOOM LAMP RELAY
PWM OUT -
PWM OUT +
OPTION RELAY 3
OPTION RELAY 2
OPTION RELAY 1
RS232C RxD
RS232C TxD
HARNESS CODE 4
HARNESS CODE 3
HARNESS CODE 2
HARNESS CODE 1
GND
GND
16
4
3
2
1
BACKUP SW 3
GLOW
+B (24V)
WASHER RELAY
8
9
6
7
20
14
24
WIPER MOTOR RELAY
CHASSIS LAMP RELAY
11
26
17
18
10
16
17
18
19
15
14
13
12
11
20
L18
YL
BU
PU
BK
5
4
3
2
1
SIG
GND
OR24V+
M
SIG
GND
5V+
ENG GOV
ACTR
4I-5496
STARTER
109-2361
ENG
OIL
SW
3T-4418
COOLANT
TEMP
SENDER
112-4009
ALTERNATOR
109-2362
RESISTOR
5L-2854
BLOCK AS.
7Y-5499
DISCONNECT SW
7N-0718 RELAY
PANEL
GG
MAIN
RELAY
3T-0376
HEATER
RELAY
085-5353
6
7
8
9
5
4
3
2
1
10
GROUND
P
S
R
L
10
1
2
3
4
5
9
8
7
6
6
7
8
9
5
4
3
2
1
10
ALT
BREAKER
9S-0174
60A
ATCH
REFUELING
RELAY
7Y-5490
BOOM
LAMP
RELAY
7Y-5490
CAB/CHASSIS
LAMP RELAY
7Y-5490
HORN
RELAY
7Y-5490
WASHER
RELAY
7Y-5490
WIPER
RELAY
7Y-5490
10A
20A
10A
L7
REDUCING
VALVE
5I-8368
TRAVEL
SPEED
4I-5674
TRENCHING
4I-5674
LEVEL
FINISH
4I-5674
HYD OIL
SENDER
4I-5394
AM RADIORADIO AM/FM
1
2
BOOM
RAISE SW
102-8042
PRESSURE SW
102-8041
TRAVEL SW
102-8041
2
1
1
2
PLATFORM
PLATFORM
PLATFORMCHASSIS
ATCH A/C
CLUTCH
SOL
7T-8600
5
4
3
2
1
5
4
10
1
2
3
4
5
PUMP
BACKUP SW
3T-4405
BACKUP
RESISTOR
102-8015
ATCH
REFUELING SW
5C-6108
FUEL
SENSOR
7Y-3848
ATCH
REFUELING
PUMP SW AS.
105-9894
-
+
L6
L7
1
2
3
4
5
9
8
7
6
OPERATOR STATION
C
4
3
2
1
10
1
2
3
4
5
9
8
7
6
LOWER
WIPER MOTOR
6C-9102
B
PP
PPB
B
C
SPEED
CHANGE SW
7N-8008
GOV
BACKUP SW
3T-4405
ONE TOUCH
LOW IDLE SW
6I-5088
CAB
CIGAR
LIGHTER
9W-0335
ACTION
ALARM
3E-6328
SERVICE
METER
6T-7337
MONITOR
7Y-5500
NEUTRAL
START SW
9W-2150
HORN SW
6I-5088
GROUND
+BATTERY
DATA -
DATA +
2
1
2
Z
200-BK
501-GN
306-GN
2
118-GY
OPERATOR STATION
+1
4
3
2
SW.
7X6387
306-PK
330-YL
306-PK
327-PK-10
306-PK
A
1
306-GN
5
A877-YL
4
3
2
1
200-BK
501-GN
1
2
OPERATOR STATION
118-GY
J
3
J
A
J
AA
ATCH
CAB LAMP
5I-8250
615-YL
200-BK
1
200-BK
615-YL
G
3
CHASSIS
LAMP
5I-8251
ATCH
BOOM
LAMP
5I-8250
ATCH
BOOM
LAMP
5I-8250
HORN
7Y-3920
HORN
7Y-3919
CHASSIS
GY
PU
BR
RED
WHITE
ORANGE
YELLOW
PINK
ABBREV COLOR
BLACK
GRAY
PURPLE
BROWN
DESCRIPTIONSYMBOL
CONNECTOR
ELECTRICAL CONNECTION
TO VEHICLE STRUCTURE
INTERNAL ELECTRICAL
CONNECTION TO SURFACE
OF COMPONENT
BLADE, SPADE, RING,
OR SCREW TERMINAL
BK
PK
YL
OR
WH
RD
GN
BU
GREEN
BLUE
CIRCUIT CONNECTED
CIRCUIT NOT CONNECTED
ATCH WIRE, CABLE,
COMPONENT
L#
CIRCUIT GROUPING
DESIGNATION
IDENT PART NO. LOC
HARNESS AS.
2
5
24
23
4
3
1
37
22
36
40
30
35
38
19
39
29
27
13
25
ENG/PUMP
CONT
4I-5383
21
23
28
10
1
2
3
4
5
9
8
7
6
MOTOR
ATCH
A/C UNIT
107-1994
A
2
MOTOR
1
2
3
4
5
6
200-BK
5
1
3
4
(113-5978)
10
1
2
3
4
5
9
8
6
6
2
1
2
1
1
6
4 4
6
1
3
ENG
SPEED SENSOR
3E-7886
AIR
HEATER
CHASSIS
B
200-BK-10
S
MOTOR
BAT
MOT
S
G
T
BB
BB
ALT
2
1
5
S
327-PK-10
306-PK
ENG SHUTDOWN
SOLENOID
2
1
F
Z
USE WITH COLD WEATHER.
NORMALLY OPEN BEFORE REFRIGERANT CHARGE.
NOTE B :
NOTE A :
UNLESS OTHERWISE SPECIFIED ALL WIRE IS 16 GAGE.
COMPONENTS ARE SHOWN INSTALLED ON AFULLY
OPERABLE MACHINE WITH THE KEY AND ENGINE OFF.
THIS SCHEMATIC IS FOR THE 312 EXCAVATOR.
7Y-3935
7Y-3936
8R-1461
7Y-3947
4I-5428
7Y-3946
110-2547
CABLE AS.
5I-8358
4I-5451
4I-5447
4I-5448
7Y-3937
WIRE AS.
7Y-3994
4I-5460
7Y-8245
105-9958
4I-5411
7Y-3868
4I-5463
113-7621
6C-9361
6C-9117
7Y-8139
110-2546
113-1159
10
1
2
3
4
5
9
8
7
6
15A
10A
10A10A
10A
15A
2
10A
10A
10A10A
10A
10A
10A
10A
A/C HEATER
CIGAR LIGHTER
BACKUP
REFUELING
KEY SW
LOWER WASHER/WIPER
WASHER/WIPER
TRAVEL ALARM
ENG/PUMP CONT
DOME LAMP
HORN
SOLENOID
MONITOR
RADIO
BOOM LAMP
CAB/CHASSIS LAMP
10A
D746-PK
NEG
POS
NEG
POS
2
1
2
1
2
1
1
2
T
PROVISION
200-BK
615-YL
4
GROUND STRAP
7G-1060
330-YL
K
A
2
1
L3
L5
L9
L4
2
1
2
1
ATCH
SPEAKER
7Y-5505
ATCH
ANTENNA
7Y-3990
ILLUMI (+)
ACC (+)
BACK UP
GND
SPEAKER (+)
SPEAKER (-)
ANTENNA
ATCH
RADIO
7Y-5433
CAB
ATCH
REFUELING
PUMP
6C-5572
MOTOR
S
-
+
ATCH
CAB LAMP
5I-8250
10
1
2
3
4
5
9
8
7
6
2
1
2
1
4
3
2
1
-
+
306-PK
4
2
UPPER
WIPER MOTOR
6C-8438
1
3
F
306-PK
A
2
1
KEY SW
7Y-3918
ENGINE
SPEED DIAL
7Y-5465
5 S4
S3
S2
S1
COM
4
3
B
C
R2
R1
ACC
START
ON
OFF
BR
PREHT
2
1
+
-
S
MOTOR
3
2
1
PROVISION
FOR ATCH
+1
6C-8839
113-0506
PROVISION FOR
ATCH SWITCH
7X6387
( RH CONSOLE )
PROVISION FOR
ATCH SWITCH
7X6388
( RH CONSOLE )
2
1
9
8
7
6
DOME
LAMP
096-0721
3
2
1
10
1
2
3
4
5
9
8
7
6
CONN 36
6C-9362
E-2
E-3
A-10
C-7
B-2
B-2
F-1
F-9
E-5
F-3
D-4
D-3
C-6
C-5
C-6
D-10
D-10
D-7
D-9
D-9
D-9
A-5
C-9
C-9
C-9
D-9
A-9
D-9
D-9GG
FF
EE
DD
CC
BB
AA
PP
MM
LL
KK
JJ
Z
Y
S
R
P
N
M
L
K
J
H
G
F
E
C
B
A
CONN 38
CONN 34 CONN 41
CONN 33
CONN 32
CONN 28
615-YL
501-GN
200-BK
118-GY
200-BK
200-BK
500-BR
E
1
2
F
CONN 63
WINDSHIELD
SW.
9G-2795
500-BR
501-CN
AIR HEATER
CONN 27
CONN 61
CONN 21
CONN 22
CONN 26
CONN 25
CONN 31
CONN 30
CONN 62
CONN 20
CONN 23
CONN 17
CONN 15
CONN 15
CONN 57
CONN 12
CONN 43
CONN 14
CONN 13
CONN 49
CONN 48
L22
ALL DASHED LINES ARE ATTACHMENTS.
WIRES THAT HAVE BATTERY VOLTAGE
WHEN THE KEY SWITCH IS OFF.
WIRES THAT HAVE BATTERY VOLTAGE
WHEN THE KEY SWITCH IS ON.
STARTING CIRCUIT.
GAUGE CIRCUIT.
ENGINE/PUMP CONTROLLER CIRCUIT.
WIPER/WASHER CIRCUIT.
HEATER AND AIR CONDITIONER CIRCUIT.
GROUND CIRCUIT.
ENGINE SHUTDOWN CIRCUIT.
AIR INLET HEATER CIRCUIT.
PROPORTIONAL
CONN 56
CONN 53
CONN 54
CONN 55
IMPLEMENT SWING
CONN 51
CONN 52
CONN 50
CONN 29
CONN 7
CONN 12
CONN 5
CONN 6
CONN 3
CONN 11
CONN 4
CONN 44
101-3897
CONN 59
CONN 42
CONN 39 CONN 45
CONN 9 CONN 10 CONN 8
CONN 2
CONN 1
CONN 58
CONN 18CONN 19
CONN 60
CONN 24
CONN 37