312 EXCAVATOR ELECTRICAL SCHEMATIC GRENOBLE USED IN SERVICE MANUAL SENR6120

Component Location
Component
Schematic
Location
Machine
Location
Component
Schematic
Location
Machine
Location
Actuator - Engine Governor A-12 3 Sensor - Eng. Speed Pickup A-10 21
Alarm - Action D-2 A Sender - Hydraulic Oil B-8 E
Alarm - Travel (ATCH) B-12 1 Sender - Engine Coolant C-10 22
Alternator B-10 3 Sensor - Fuel B-4 38
Battery D-12 5 Solenoid - Eng/Pump Cont. A-8 B
Block AS D-9 D Solenoid - Eng. Shutdown B-12 3
Breaker D-9 D Solenoid - Conb./Single (ATCH) A-5 F
Controller- Eng/Pump A-7 D Solenoid - Start Aid A-12 24
Converter - (ATCH) D-6 7 Solenoid - A/C Clutch (ATCH) B-10 34
Fuse - Block F-7,8,9 D Solenoid - Level Finish A-8 23
Heater - Air A-12 2 Solenoid - Trenching A-8 23
Horn B-2 8 Multi-Switch - Joystick RH C-3 C
Lamp - Boom (ATCH) B-2 31 Multi-Switch - Joystick LH F-3, F-2 B
Lamp - Cab (ATCH) E-1,F-1 13 Switch - Overload Warning Press B-5 F
Lamp - Chassis A-2 29 Switch - Overload Warning (ATCH) C-4 C
Lamp - Dome C-6 A Switch - Combined (ATCH) A-2 C
Lighter - Cigar D-2 A Switch - Windshield D-2 A
Meter - Service E-2 A Switch - Coolant A-12 35
Monitor E-2 A Switch - Press (ATCH) B-9 F
Motor - Lower Washer (ATCH) C-12 28 Switch - Accel. Backup C-4 C
Motor - Lower Wiper F-1 12 Switch - AS C-2 C
Motor - Starter A-10 14 Switch - Boom Raise C-8 E
Motor - Washer C-12 28 Switch - Disconnect D-9 D
Motor - Upper Wiper F-2 30 Switch - Engine Oil B-10 36
Pump - Refueling (ATCH) A-3 17 Switch - Governor Backup C-5 B
Relay - Boom Lamp E-8 D Switch - Implement B-8 E
Relay - Chassis/Cab Lamp A-2 D Switch - Neutral Start F-2 C
Relay - Start D-7 D Switch - PS Valve Backup F-4 C
Relay - Horn E-7 D Switch - Radio (ATCH) E-4 A
Relay - Main D-7 D Switch - Refrigerant B-12 9
Relay - Refueling E-7 D Switch - Throttle Pos. C-2 C
Relay - Start D-7 D Switch - Refueling (ATCH) A-4 38
Relay - Washer E-8 D Switch - Refueling Pump (ATCH) A-3 16
Relay - Wiper E-8, 9 D Switch - Key Start C-2 C
Resistor - Air Heater A-10 D Switch - Travel C-8 E
Resistor - Backup F-5 C Unit - A/C (ATCH) E-6 39
Resistor - (Relay Panel) D-8 D Unit - Heater E-6 10
Resistor B-12 3
A = Located inside cab.
B = Located inside of L.H. Console.
C = Located inside of R.H. Console.
D = Located in side compartment behind the cab.
E = Located around hyd. oil tank.
F= Located around pilot manifold.
Machine locations are repeated for components located close together.
Connector Location¹
Connector Number Schematic Location Machine Location
CONN 1 D-12 19
CONN 2 D-12 1
CONN 3 D-11 D
CONN 4 D-10 D
CONN 5 D-10 D
CONN 6 F-9 D
CONN 7 F-9 D
CONN 8 E-9 D
CONN 9 D-9 D
CONN 10 C-8 E
CONN 11 C-8 E
CONN 12 A-6 18
CONN 13 C-6 4
CONN 14 E-5 B
CONN 15 E-5 B
CONN 16 E-5 B
CONN 17 C-5 11
CONN 18 C-5 11
CONN 19 B-5 11
CONN 20 D-4 C
CONN 21 D-4 C
CONN 22 B-3 F
CONN 23 B-3 C
CONN 24 C-3 C
CONN 25 D-3 6
CONN 26 D-3 6
CONN 27 D-3 6
CONN 28 D-3 C
CONN 29 E-3 15
CONN 30 F-3 B
CONN 31 E-2 15
CONN 32 B-2 8
CONN 33 A-2 C
CONN 34 F-9 F
CONN 35 C-8 E
CONN 36 E-2 15
¹The connectors shown in this chart are harness to harness and
special use connectors. Connectors which join a harness to a
component are generally located at on near the component. See
the component location chart.
Related Electrical Service Manuals
Title Form Number
Engine / Pump Control SENR6038
Starter Motor SENR3550
Alternator SENR3685
Resistor, Sender, and Solenoid Specifications
Part No. Component Resistance (Ohms)¹
102-8015 Backup Resisitor 41 ± 0.6%
5L-2854 Resisitor 4 ± 5.0%
3E-7886 Engine Pickup Sender 100 - 200
112-4009 Engine Coolant Temp Sender 1100
6T-5859 Combination / Single (ATCH) Solenoid 33.7 ± 1.0%
3T-9493 Start Aid Solenoid 1.5
¹ At room temperature.
Real Time Error Codes
Code Description of Problems
E00 No Problem.
E01 Engine oil pressure is too low.
E02 Engine coolant temperature is too high.
E03 Hydraulic oil temperature is too high.
E04 Battery voltage is too high.
E05 Alternator terminal P is open.
E06 Engine speed sensor is not installed correctly or it's circuit is open.
E07 Engine speed is not normal.
E09 Voltage of governor actuator feedback sensor is too low.
E10 Governor actuator feedback sensor circuit is open or shorted to battery voltage.
E11 Governor actuator feedback sensor circuit is shorted to body ground.
E12 Governor actuator feedback sensor voltage is not stable.
E13 Governor actuator motor (+) circuit is shorted to body ground.
E14 Governor actuator motor does not rotate or motor circuit is shorted to battery voltage.
E15 Governor backup switch is in "Man" (BACKUP) position or governor actuator motor (+) circuit is open.
E16 Proportional reducing valve (+) circuit is shorted to body ground.
E17 Proportional reducing valve (+) circuit is shorted to battery voltage.
E18 Proportional reducing valve circuit is open.
E25 Engine coolant temperature sensor circuit is shorted to body ground.
E27 Hydraulic oil temperature sensor circuit is shorted to body ground.
E31 Controller receives signal of engine speed other than specified ten from engine speed dial.
E32 There is more than 100 rpm difference between engine speed dial setting and actual rpm.
E33 Digital output circuit is shorted to (+) battery Voltage.
E34 Governor actuator remains deactivated an elapsed time of 2.5 seconds after engine speed dial setting.
E36 Monitor takes at least one second to respond to controller's signal.
E37 Monitor RAM is not normal.
E38 Controller is informed of it's error signal by monitor.
E39 Controller detects its error signal by itself.
E40 Error in controller memory.
E41 A controller for a different machine is installed or there is a harness code problem.
E48 Engine stalls.
Off Machine Switch Specification
Part No. Function Actuate Deactuate Contact Position
114-5334 Refrigerant Pressure 275 to 1750 kPa N/A Normally
(40 to 255 psi) N/A Open
102-8042 Boom Raise Pressure 2450 ± 441 kPa 1470 kPa MIN Normally
(355 ± 64 psi) (213 psi MIN) Open
102-8041 Implement Pressure 1225 ± 343 kPa 735 kPa MIN Normally
Travel Pressure (178 ± 50 psi) (107 psi MIN) Open
107-0611 Engine Oil Pressure 93 ± 21 kPa 70 ± 21 kPa Normally
(13.5.0 ± 3.0 psi) (10.0 ± 3.0 psi) Open
Wire Description
Number
Color
Description
Number
Color
Description
Power Distribution Circuits
491 PK Hyd. Oil Temp Sensor
101 RD Bat (+) 492 GY Coolant Sensor
102 BU Hd Lmp 495 GN Fuel Level Sensor
103 YL Aux Ckt
Accessory Circuits
105 BR Key Sw 500 BR Wiper - Front (Park)
109 OR Alt Output (+) Term. 501 GN Wiper - Front (Low)
112 PU Main Power Rly Output 506 PU Washer - Front
113 OR Opr Mon Panel 513 OR A/C Compressor/Refrigerant Pressure Switch
114 GN Warning Horn (Forward) 519 PK Thermostat To Refrigerant Press. SW
115 PK Aux Ckt 575 YL Wiper - Aux (Park)
118 GY Aux Ckt 576 PK Wiper - Aux (Low)
120 YL Aux Ckt 578 BU Wiper - Aux
121 YL Back Alarm To Lamp 586 BR Aux Hyd - Close
122 BU Aux Ckt
Lighting Circuits
124 GN A/C 607 PK Flood Lamp - Front
129 BU Aux Ckt 615 YL Cab Flood Lamps / Rops
135 BU Aux Ckt 616 BU Bucket Flood Lamp / Boom Flood Lamp
142 BU Aux Ckt
Control Circuits
149 PU Aux Ckt 763 BU Torque Converter SW.
151 GN Aux Ckt 786 GN Eng Speed Cont. - Hi Press SW
152 BU Aux Ckt 788 YL Eng. Speed (+)
154 BU Aux Ckt 791 PK Eng. Speed Cont. - Lo Sol
168 GN Aux Ckt 792 OR Undisrupted Proportional Sol.
184 BU Aux Ckt A755 PK Throttle SW #1
185 YL Aux Ckt A756 BU Throttle SW #2
Ground Circuits
A757 GY Throttle SW #3
200 BK Main Chassis A758 BR Throttle SW #4
201 BK Operator Monitor Return A761 PU Electronic Pump Cont. Throttle Ground
210 BK Converter Output (24/12 Volt) A762 PU Electronic Pump Cont. Eng. Speed Ground
235 BK Electronic Pump Ctrl. Gnd A763 GY Electronic Pump Cont. Decel (-)
264 BK Electronic Pump Ctrl. Ident Code 3 A768 BU Pump Control Valve #1 (+)
265 BK Electronic Pump Ctrl. Ident Code 2 A769 GY Pump Control Valve #2 (-)
266 BK Electronic Pump Ctrl. Ident Code 1 A770 PK Electronic Pump Control Bypass SW to Resistor
267 BK Electronic Pump Ctrl. Ident Code 0 A771 PU Float SW
Basic Machine Circuits
A877 PU Left Console Stop / Go SW to Park Brake
304 WH Starter Relay No. 1 Output A983 BU Washer Relay
306 GN Starter Relay Coil To Neut Start SW Or Key SW B730 OR Electronic Pump Control Ps Valve (-)
307 OR Key SW To Neutral Start SW. B731 WH Electronic Pump Control Ps Valve (+)
308 YL Main Power Relay Coil B737 GN Electronic Pump Control to Pressure Switch
309 GY Alternator Regulator Term. B739 WH Electronic Pump Control Display Switch Hold Input
311 WH Start Aid Sol To Temp SW B740 OR Electronic Pump Control Display Switch Clr Input
320 OR Horn Relay Coil to SW B751 BU Centershaft Lock Sol
321 BR Backup Alarm Lamp Travel Alarm B786 BU Low Idle SW
322 GY Warning Horn B789 BR Governor Actuator (-) (Backup SW to Power Control)
323 WH Fuel Pump Power B790 OR Governor Actuator (+) (Backup SW to Power Control)
325 PK Fuel Pump Relay Call Out D746 PK Alt Signal to Anti-Start Relay
327 PK Shutdown Solenoid D764 GN Electronic Pump Control Boom Pressure Switch
332 BU Shutdown SW to Shutdown Ctrl. 877 YL Glow Plug Magnetic SW to Glow Plug
334 BU Start Aid Sol. #2 A877 PU Left Console Stop / Go SW to Park Brake SW
365 YL Fuel Pump Relay to Switch 952 OR Hammer SWAB
Monitoring Circuits
A983 BU Throttle Cont - Signal
403 GN Alternator (R) Term. B955 YL Excavator System Lock Limit Switch
405 GY Opr. Mon. Oil Press. (Low Setting) B956 PK Excavator System Lock Sol.
410 WH Opr Mon Fault Alarm B964 YL Trenching Sol.
439 YL Lamp Indicator B965 GY Level Finish Sol.
A
3
4
5
6
8
9
10
11
12
14
15
13
16
B
C
D
E
1
2
17
18
19
21
22
23
24
27
28
29
30
31
35
34
36
38
7
F
39
A
3
4
5
6
8
9
10
11
12
14
15
13
16
B
C
D
E
1
2
17
18
19
21
22
23
24
27
28
29
30
35
34
36
38
7
F
39
15
28
31
28
15
18
Machine Harness Connector And Component Locations
SENR6237-01
December 1999
312 Excavators Electrical System
6BL1-UP
©
1999 Caterpillar
All Rights Reserved
Printed in U.S.A.
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.
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.
START AID CIRCUIT.
304-WH-10
235-BK
327-PK
RESISTOR
5L-2854
327-PK
327-PK
D746-PK
B AIR
HEATER
035-8059
ATCH
START AID
SOL. 3T-9493
NOTE C
334-BU
1
1
2
1
2
2
BK-00
ALT
BB
ENG
SHUTDOWN SOL
101-3897
T~
B
G
S
MOTBAT
MOTOR
235-BK
RD
BK
878-WH
B
200-BK
B B
ENG
STARTER
CHASSIS
ENG
PICKUP
3E-7886
ATCH
COOLANT SW
8N-1693
NOTE C
2
1
ATCH A/C
CLUTCH
SOL
101-1759
NOTE D
B
B
2
1
200-BK
405-GY
ENG OIL PRESSURE SW
107-0611
A762-PU
788-YL
200-BK
200-BK
113-OR
200-BK
A761-PU
A763-GY
B751-YL
513-OR
200-BK
200-BK
109-OR-6
403-GN
309-GY
492-GY
200-BK
ALTERNATOR
109-2362
COOLANT TEMP SENDER
112-4009
STARTER
109-2361
ENG GOV
ACTR
4I-5496
5V+
GND
SIG
M
24V+ OR
GND
SIG
1
2
3
4
5
BK
PU
BU
YL
200-BK
L27
L26
A771-BU
L4
L27
L31
L27
AJ
L27
L27
L26
L26
L19
L22
L25
B
L24
L23
B
P
B+
W
D
B-
B
B
B
B
AA
B
EE
EE
B
L23
L3
L3
L3
L3
ATCH PRESS SW
119-9985
NOTE G
ATCH-PRESS SW
101-3082
NOTE G
BK
NOTE G
NOTE G
NOTE G
NOTE G
NOTE G: USE WITH ATCH MEDIUM PRESSURE
311-YL
122-BU
AK
AK
AJ
T~
E
501-GN
500-BR
WINDSHIELD
SWITCH
9G2795
A877-YL
A877-YL-14
1
2
200-BK
A771-PU
AK
A877-YL
2
1
200-BK
A877-YL
G
A771-PU
311-YL
200-BK
A771-PU
R
R
R
R
1
2
3
RD
ATCH MED. PRESS
VALVE GP
117-2989
NOTEG
AH
210-BK
135-BU
200-BK
103-GY
102-BU
CONVERTER
108-9968
ANTENNA
7Y-3990
3
2
4
1
3
GROUND
+12 VOLT
+ BATTERY
GROUND
1
2
3
WH/BK-18
WH/RD-18
2
1 RD-18
BK-18
2 OUTPUT
1 +BATTERRY
GROUND
1
C-7
HEATER UNIT
107-1995 / 118-8674
1
2
3
4
5
365-YL
325-PK
200-BK
323-WH
200-BK
607-PK
616-BU
322-GY
200-BK
235-BK
200-BK
200-BK
B
B
P
P
N
NB
H
H
G
2
L11
L9
L1
306-GN
E
EE
E
G
G
A
A
E
L5
L2
6
7
5
4
3
2
1
EF
AA
HHHH
ATCH
CAB LAMP
5I-8250
L2
L1
L22
L11
L2
L8
L10
RELAY PANEL
RELAY PANEL
RELAY PANEL
F
L10
H
A
H
A
A
K
200-BK
K
A
K
L9
L9
L6
L6
L8
L6
L5
L4
L12
615-YL
200-BK
200-BK
OPERATOR STATION
B B
B
B
B
B
B
B
B
L22
L21
AA BB CC
FUSE
10A 9W-1442
15A 9W-1441
20A 9W-1446
615-YL
DD
CC
200-BK
ATCH
CAB LAMP
5I-8250
D
F
BATTERY
3T-5760
9X-3404(NOTE B)
D
F
L20
L29
L29
L19
L16
L14
L13
KK
LL
LL
KK
KK
LB
AH
L
B
B
B
B
A
L
LA
LA
L20
L18
B
ATCH-RADIO AM/FM
3A-8966
200-BK
200-BK
L16
L17
L17
L14
L13
102-BU
L12
DD
B A
B
B A
AA
AA
A
AAAA
113-OR
B751-YL
513-OR
103-GY
A763-GY
A768-BU
A769-GY
309-GY
403-GN
323-WH
365-YL
101-RD-4
109-OR-6
616-BU
607-PK
142-BU-14
403-GN
309-GY
A769-GY
A768-BU
A763-GY
513-OR
B751-YL
D764-GN
B965-GY
B964-YL
B737-GN
A771-PU
2
L19
1
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
L25
105-BR
151-GN-18
952-OR-18
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
952-OR-18
200-BK-18
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
1
506-PU
2
786-GN
121-YL
791-PK
792-OR
A983-BU
184-BU
877-YL
7
519-PK
513-OR
321-BR
121-YL
ATCH
TRAVEL
ALARM
3T-1444
200-BK-18
121-YL
321-BR
513-OR
519-PK
321-BR
121-YL
519-PK
513-OR
151-GN-18
AD
PROVISION
FOR ATCH
AD
235-BK
267-BK
ATCH
COMB./SINGL
SOL
6T-5859
NOTE F
151-GN-18
AG
A
CHASSIS
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
6
7
8
9
5
4
3
2
1
10
491-PK
405-GY
124-GN-14
519-PK
615-YL
103-YL
200-BK-14
WASHER
7T-8890
ATCH
LOWER
WASHER
7T-8890
266-BK
578-BU
200-BK
200-BK
506-PU
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
321-BR
D764-GN
D746-PK
A762-PU
788-YL
405-GY
492-GY
A761-PU
IMPLEMENT SW
495-GN
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 +
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
32
22
12
33
34
21
31
15
763-BU
B956-PK
B964-YL
B786-BU
B965-GY
B737-GN
A771-PU
491-PK
OPTION SW 2
OPTION SW 1
A755-PK
A756-BU
A757-GY
A758-BR
410-WH
308-YL
OPTION SENSOR
HYD OIL LEVEL SW
ENG OIL LEVEL SW
HYD OIL TEMP SENSOR
COOLANT LEVEL SW
OPTION SOLENOID
ATTACHMENT
TRAVEL ALARM
BOOM RAISE SW
ALTERNATOR (P TERM.)
786-GNBOOM 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
576-GY
AG
AG
576-GY
L18
235-BK
235-BK
103-GY
AH
AH
102-BU
AG
L19
2
1
152-BU
576-GY
576-GY
152-BU
200-BK-18
NOTE F
607-PK
200-BK
NOTE F
323-WH
NOTE F: USE WITH ATCH COMBINED/ SINGLE
NOTE F
200-BK
AC
365-YL
325-PK
AC
AC
AD
ATCH CONTROL AR SINGLE 129-4701
AE
1
2
952-OR-18
154-BU-18
2
1
151-GN-18
ATCH- COMBINED SW
3T3132
NOTE F
151-GN-18
154-OR-18
AD
AE
AF
AF
200-BK-18
952-OR-18
AD
952-OR-18
200-BK-18
1
2
1
2
952-OR-18
G
G
G
A
1
2
3
4
B737-GN
D764-GN
200-BK
A771-PU
491-PK
B964-YL
B965-GY
763-BU
A768-BU
A769-GY
BLOCK AS.
7Y-5499
DISCONNECT SW
7N-0718
RELAY
PANEL
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
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
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
L
DIODE
121-1022
BK-00
200-BK
L12
501-GN
308-YL
200-BK
L
S
513-OR
6
7
8
9
5
4
3
2
1
10
519-PK
1
2
BK
RD
877-YL
A983-BU
791-PK
792-OR
121-YL
506-PU
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
109-OR-6
200-BK
308-YL
112-PU-14
101-RD-6
101-RD-14
101-RD-14
10
1
2
3
4
5
9
8
7
6
120-YL
112-PU-14
105-BR
308-YL
6
7
8
9
5
4
3
2
1
10
ALT
BREAKER
9S-0174
60A
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
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
792-OR
500-BR
118-GY
10A
20A
10A
BK-00
BK-00 BK-00
A-5
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
112-PU-14
ENG/PUMP
CONT
5I-8368
TRAVEL
SPEED
4I-5674
TRENCHING
4I-5674
LEVEL
FINISH
4I-5674
HYD OIL
SENDER
4I-5394
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
112-PU-14
BU
1
2
B737-GN
112-PU-14
BOOM
RAISE SW
102-8042
IMPLEMENT SW
102-8041
TRAVEL SW
102-8041
200-BK
D764-GN
2
1
1
2
A771-PU
200-BK
200-BK
B737-GN
PLATFORM
PLATFORM
PLATFORMCHASSIS
200-BK
124-GN-14
519-PK
103-YL
615-YL
615-YL
200-BK
103-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
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
5
4
3
2
1
200-BK
103-YL
5
4
200-BK
B740-OR
185-YL
B789-BR
B739-WH
B790-OR
B751-YL
578-BU
152-BU
152-BU
575-YL
576-PK
10
1
2
3
4
200-BK
200-BK
200-BK
200-BK
200-BK-14
5
PS VALVE
BACKUP SW
3T-4405
BACKUP
RESISTOR
102-8015
ATCH
REFUELING LEVEL SW
5C-6108
FUEL
SENSOR
7Y-3848
325-PK
325-PK
365-YL
GN
GY
235-BK
235-BK
200-BK
616-BU
322-GY
607-PK
323-WH
365-YL
325-PK
325-PK 325-PK
200-BK
607-PK
118-GY
501-GN
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
200-BK
2
1
AC
878-WH
FOR ATCH RADIO
AM RADIO 3A-8966
C
L6
L7
122-BU
120-YL
122-BU
120-YL
T
122-BU
F
122-BU
120-YL
763-BU
763-BU
200-BK
OPERATOR STATION
10
1
2
3
4
5
9
8
7
6
UPPER
WIPER MOTOR
6C-9102
PP
PPB
B
ACCEL
BACKUP SW
7N-8008
GOV
BACKUP SW
3T-4405
578-BU
152-BU
575-YL
152-BU
576-PK
B789-BR
B739-WH
B790-OR
B740-OR
200-BK
185-YL
1
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
2
A
B789-BR
B790-OR
CAB
CIGAR
LIGHTER
9W-0335
ALARM
9G-9813
SERVICE
METER
6T-7337
MONITOR
7Y-5500 / 111-9748
410-WH
113-OR
200-BK
403-GN
B956-PK
B955-YL
129-BU
129-BU
200-BK
320-OR
576-PK
152-BU
575-YL
307-OR
306-GN
A
2
NEUTRAL
START SW
9W-2150
307-OR
306-GN
200-BK
575-YL
152-BU
576-PK
306-GN
307-OR
200-BK
B786-BU
308-YL
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
GROUND
+BATTERY
DATA -
DATA +
B786-BU
G
1
495-GN
Z
200-BK
501-GN
306-GN
2
118-GY
OPERATOR STATION
+1
4
3
2
SWITCH AS
7X6387
PRESS. SW
118-7723
2
3
A
1
1
439-YL
586-BR
U
439-BU
586-BR
AB
AB
OVERLOAD WARNING PRESS. SW 118-7722
5
U
200-BK
575-YL
200-BK-18
576-PK
A877-YL
B-5
200-BK
2
154-BU
154-OR-18
952-GN-18
154-BU-18
4
3
2
1
NOTE E: USE WITH ATCH OVERLOAD WARNING
200-BK
501-GN
LOW IDLE SW
C-2
OPERATOR STATION
118-GY
RIGHT SW
3
HAMMER SW
G
200-BK
AA
615-YL
G
ATCH
BOOM
LAMP
5I-8250
ATCH
BOOM
LAMP
5I-8250
HORN
7Y-3920
HORN
7Y-3919
616-BU
200-BK
CHASSIS
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
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
323-WH
GY
PU
BR
RED
WHITE
ORANGE
YELLOW
PINK
ABBREV COLOR
BLACK
GRAY
PURPLE
BROWN
DESCRIPTIONSYMBOL
CONNECTOR
ELECTRICAL CONNECTION
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
NOTE D
A
2
MOTOR
1
2
3
4
5
6
304-WH-10
327-PK
334-BU
322-GY
5
1
3
4
10
1
2
3
4
5
9
8
6
6
A761-PU
492-GY
405-GY
788-YL
A762-PU
D746-PK
D764-GN
321-BR
308-YL
506-PU
200-BK
200-BK
578-BU
2
1
2
1
1
6
4 4
6
1
3
YL
495-GN
616-BU
322-GY
607-PK
GN
L2
BK
RD
RR
U
323-WH
365-YL
586-BR
311-WH
200-BK
200-BK
1
2
308-YL
BK-00
200-BK
200-BK-6
U
439-YL
308-YL
RR
200-BK
200-BK-6
200-BK
ATCH OVERLOAD
WARNING BUZZER
113-4683
NOTE E
200-BK
ATCH OVERLOAD
WARNING SW
7X-6386
NOTE E
NOTE E
B
200-BK
200-BK
101-RD-4
304-WH-10
101-RD-4
334-BU
492-GY
309-GY
D746-PK
5
403-GN
J
HORN SW
RIGHT SW
LEFT SW
A761-PU
J
320-OR
B
B751-YL
A763-GY
109-OR-6
334-BU
YL
GNJ
2
RD
1
BU
BK
GY
MULTISWITCH JOYSTICK-LH
113-2523
A
320-OR
200-BK
F-2
334-BU
513-OR
405-GY
B
327-PK
A762-PU
788-YL
113-OR
200-BK
F
Z
USE WITH COLD WEATHER.
NORMALLY OPEN BEFORE REFRIGERANT CHARGE.
NOTE B:
NOTE A:
THIS SCHEMATIC IS FOR THE 312 EXCAVATOR.
615-YL
A-9
D-9
C-9
C-9
C-9
8R-1461
7Y-3947
4I-5428
7Y-3946
110-2547
EE
DD
CC
BB
AA
CABLE AS.
A-5
D-7
D-9
D-9
D-7
WIRE AS.
B-2
B-2
F-1
F-9
E-5
F-3
D-4
D-3
C-6
C-5
E-5
D-10
500-BR
308-YL
A877-YL-14
RESISTOR
7W-1251
L
L
L
1
142-BU-14
322-GY
365-YL
323-WH
607-PK
616-BU
101-RD-6
109-OR-6
109-OR-6
2
JJ
10
1
2
3
4
5
9
8
7
6
15A
10A
15A10A
10A
15A
2
10A
10A
10A10A
124-GN-1410A
10A 129-BU
10A
10A
185-YL-14
168-GN
105-BR
A/C HEATER
CIGAR LIGHTER
BACKUP
REFUELING
LOWER WASHER/WIPER
WASHER/WIPER
TRAVEL ALARM
ENG/PUMP CONT
DOME LAMP
HORN
SOLENOID
MONITOR
RADIO
BOOM LAMP
CAB/CHASSIS LAMP
308-YL
10A
ATCH
REFRIGERANT
SW
114-5334
(NOTE A)
NOTE D
S
NOTE D
B-8
C-11
E-3
E-3
A-5
C-8
E-3
A-5
C-12
2
MAIN RELAY
3T-0376
L
L
L
L
1
MM
START RELAY
113-2375
304-WH-10
JJ
KK
2
1
A
306-GN
327-PK
334-BU-14
327-PK
NEGPOS
NEGPOS
2
1
2
1
2
1
B737-GN
1
2
200-BK
A763-GY
T~
304-WH-10
D764-GN
200-BK
A771-PU
B789-BR
L
878-WH
142-BU-14
334-BU-14
K
A
A770-PK
A763-GY
A770-PK
B730-OR
2
1
L9
2
1
B789-BR
1
ATCH
RADIO SW
7X-6386
1
2
CAB
200-BK
200-BK
200-BK
200-BK
200-BK
MM
C
B731-WH
122-BU
122-BU
120-YL
B730-OR
185-YL
E-5
122-BU
365-YL
B
1
2
B
ATCH
REFUELING
PUMP SW AS.
105-9894
-
+
B
CHASSIS
LAMP
5I-8251
2
1
ATCH
REFUELING
PUMP
6C-5572
10A 15A 20A
A877-YL
L2
L1
MOTOR
S
-
+
E-6
115-9149
5I-8358
122-1846
4I-5447
4I-5448
7Y-3937
7G-1060
NN
NN
G
2
1
F
E
E-1
10
1
2
3
4
5
9
8
7
6
2
1
4
3
2
1
L1
L30
-
+
D-10
NOTE D: USE WITH ATCH A/C UNIT
500-BR
501-GN
RD
BU
E
BK
GY
MULTISWITCTH JOYSTICK-RH
113-2524
4
2
ATCH- LOWER
WIPER MOTOR
6C-8438
1
3
F
615-YL
501-GN
200-BK
118-GY
200-BK
952-OR-18
575-YL
152-BU
576-PK
105-BR
307-OR
308-YL
309-GY
A758-BR
A757-GY
A756-BU
A755-PK
200-BK
2
1
200-BK
2
1
334-BU-14
7Y-3918
THROTTLE
POS SW
7Y-5465
5 S4
S3
S2
S1
COM
4
109-OR-10
327-PK
877-YL
3
B
C
R2
R1
ACC
START
ON
OFF
BR
PREHT
2
1
-
S
200-BK
MOTOR
3
2
1
+1
E-3
119-6933
117-3866
118-1991
129-5660
7Y-8105
128-4032
131-4970
126-3475
128-9403
122-8023
137-1429
6C-9362
7Y-3994
4I-5460
7Y-8245
123-0963
4I-5411
7Y-3868
4I-5463
113-7621
6C-9361
6C-9117
106-0026
113-1159
116-2407
106-0027
117-7028
142-0501
6C-8839
RR
PP
MM
LL
KK
JJ
NN
AK
AJ
AH
AG
R
AE
AD
AC
AF
AB
U
Z
P
N
M
L
K
J
H
G
F
E
C
A
S
T
D
B
Y
PROVISION FOR
ATCH SWITCH
7X6387
( RH CONSOLE )
PROVISION FOR
ATCH SWITCH
7X6388
( RH CONSOLE )
2
1
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
9
8
7
6
DOME
LAMP
096-0721
A768-BU
B731-WH
B730-OR
185-YL
200-BK
3
2
1
334-BU
142-BU-14
142-BU-14
200-BK
3 2 1
C
B
A
200-BK
200-BK
200-BK
L7
10
1
2
3
4
5
9
8
7
6
UNLESS OTHERWISE SPECIFIED ALL WIRE IS 16 GAUGE.
FOR START AID GP
NOTE C: USE WITH ATCH START AID
ACTION
TO MACHINE STRUCTURE
KEY START SW
KEY START SW
KEY START SW
COMPONENTS ARE SHOWN INSTALLED ON A FULLY OPERABLE
MACHINE WITH THE KEY START SW AND ENGINE OFF.
(113-5978 CHG H03)
CONN 1
CONN 2
CONN 3
CONN 4
CONN 5
CONN 34
CONN 6
CONN 7
CONN 8
CONN 9
CONN 11
CONN 10
CONN 35
CONN 13
CONN 17
CONN 18
CONN 19
CONN 14
CONN 15
CONN 16
CONN 20 CONN 21
CONN 25
CONN 26 CONN 27
CONN 28
CONN 24
CONN 23
CONN 30
CONN 29
CONN 36
CONN 31
CONN 12
CONN 22
CONN 32
CONN 33
CONN 33
+
NOTE E
A