SENR3144
October 1985
776B Tractor & 777B Truck
Power Train
TRACTOR #:
6JC1-UP
TRUCK #:
4YC1-UP
©
1985 Caterpillar
All Rights Reserved
Printed in U.S.A.
Electrical System
Circuit
Number
Color Description
Circuit
Number
Color Description
Power Distribution Circuits
Machine Basic Circuits
101
RD
BATTERY
301
BU
STARTER NO. 1 SOLENOID TO RESISTOR
102 BU HEAD LAMP
302 OR
STARTER NO. 1 TO DIAGNOSTIC /
RESISTOR TO DIAGNOSTICS
103
YL
DOME/DASH LAMP / PARK, TAIL LAMP
304
WH
STARTER RELAY NO. 1 OUTPUT
105
BR
KEY SWITCH
306
GN
STARTER RELAY COIL / NEUTRAL START SWITCH
106
WH
MAIN POWER RELAY / INPUT
308
YL
MAIN POWER RELAY COIL
107
WH
ENGINE SHUT DOWN
310
PU
ETHER SWITCH TO ETHER SOLENOID
108
BU
MISC WIPER, DOME LAMP, CIGAR LIGHTER
311
WH
ETHER SOLENOID TO TEMPERATURE SWITCH
109
OR
ALTERNATOR
312
PK
STARTER NO. 2 SOLENOID TO RESISTOR
110 GN WINDSHIELD WIPER SWITCH (RIGHT)
313 GY
STARTER NO. 2 TO DIAGNOSTIC /
RESISTOR TO DIAGNOSTIC
111
YL
WINDSHIELD WIPER SWITCH (LEFT)
314
PU
STARTER RELAY NO. 2 OUTPUT
112
PU
MAIN POWER RELAY / OUTPUT
321
BR
BACKUP ALARM/LAMP
113
OR
OPERATOR MONITOR PANEL
322
GY
WARNING HORN (FORWARD)
114
GN
WARNING HORN (FORWARD)
323
WH
FUEL TRANSFER PUMP POWER
115
PK
FLOOD LAMP (FRONT)
324
BU
DIFFERENTIAL LOCKUP SOLENOID
116
BR
FLOOD LAMP (REAR)
325
PK
FUEL PUMP RELAY OIL PRESS. SWITCH
117
YL
FLOOD LAMP (SIDE)
326
PU
KEY SWITCH "C" TERMINAL
118
GY
WINDSHIELD WIPER SWITCH (FRONT)
327
PK
SHUTDOWN SOLENOID
119
PK
WINDSHIELD WIPER SWITCH (REAR)
328
RD
SHUTDOWN MODULE “OFF”
120
YL
CONVERTER (24 V to 12 V)
Monitoring Circuits
121
YL
BACKUP ALARM/LAMP/TRAVEL ALARM TIMER
400
GN
SERVICE METER SWITCH
122
BU
AIR DRYER
403
GN
ALTERNATOR (R) TERMINAL
123
WH
GAGES (SERVICE METER, TORQUE CONV SOL)
404
YL
OPERATOR MON PANEL HYDRAULIC OIL TEMP
124
GN
AIR CONDITIONER
405
GY
OPERATOR MON PANEL OIL PRESSURE
125
OR
FUEL TRANSFER PUMP
406
PU
OPERATOR MON PANEL COOLANT TEMP
126 PK TRANSMISSION CONTROL
407 PK
OPERATOR MON PANEL CONV /
RETARDER OIL TEMP
127
OR
CAB FLOOD LAMP
408
WH
OPERATOR MON PANEL BRAKE PRESS. (AIR)
128
PK
KICKOUT SOLENOID SWITCH
409
OR
OPERATOR MON PANEL NEUTRAL
129
BU
CIGAR LIGHTER
410
WH
OPERATOR MON PANEL FAULT ALARM
130
GN
STOP LAMP
411
PK
OPERATOR MON PANEL MASTER FAULT LAMP
131
BR
FIRE CONTROL-OPERATOR WARNING
412
BU
OPERATOR MON PANEL COOLANT FLOW
132
PK
ANTISPIN CONTROL
413
BR
OPERATOR MON PANEL FUEL PRESSURE
133
OR
PROGRAMMED ELECTRONIC ENG CONT SOL
414
PK
OPERATOR MON PANEL LOW FUEL
134
PK
PROGRAMMED ELECTRONIC ENG CONT LOGIC
415
GN
OPERATOR MON PANEL TEST SWITCH
136
GN
SUPPLEMENTAL STEERING
416
OR
SECONDARY STEERING SWITCH
137
RD
STEERING MOTOR INDICATOR
417
GY
PRIMARY STEERING SWITCH
138 GN AUTOMATIC LUBE PUMP (TRUCK)
418 YL
OPERATOR MON PANEL OIL PRESSURE
(HIGH SETTING)
141
PK
AUXILIARY HEATER
419
YL
OPERATOR MON PANEL PARKING BRAKE
Ground Circuits
420 OR
OPERATOR MON PANEL FUEL FILTER /
LOW ACCUM PRESS.
200
BK
MAIN CHASSIS
421
BU
OPERATOR MON PANEL FAULT LAMP (SCRAPER)
201
BK
OPERATOR MONITOR PANEL
422
YL
OPERATOR MON WARNING HORN (SCRAPER)
202
BK
TRANSMISSION CONTROL
423
GY
OPERATOR MON PANEL TEST SWITCH (SCRAPER)
203
BK
CHASSIS DIAGNOSTIC
424
GY
OPERATOR MON PANEL POWER TRAIN TEMP
204
BK
OPERATOR MONITOR PANEL (SCRAPER)
425
PK
OPERATOR MON PANEL POWER TRAIN OIL LEVEL
205
BK
INSTRUMENT
426
BR
OPERATOR MON PANEL POWER TRAIN OIL FILTER
206 BK BATTERY SIDE OF DISCONNECT
427 GN
OPERATOR MON PANEL POWER TRAIN OIL FILTER
JUMPER
207
BK
STARTER DIAGNOSTIC
428
OR
OPERATOR MON PANEL TRANSMISSION OIL TEMP
212
BK
ANTISPIN CODING PIN 16
429
YL
OPERATOR MON PANEL BRAKE OIL TEMP
213 BK ANTISPIN CODING PIN 17
431 GN
OPERATOR MON PANEL LOW TRANSFER PUMP
PRESS.
214
BK
ANTISPIN CODING PIN 18
432
PK
OPERATOR MON PANEL BRAKE PRESSURE (OIL)
215 BK ANTISPIN CODING PIN 19
433 BU
OPERATOR MON PANEL BRAKE PRESS. (OIL)
JUMPER
216 BK ANTISPIN CODING PIN 20
434 BU
OPERATOR MON PANEL POWER TRAIN TEMP
JUMPER
217 BK TRANSMISSION COOING PIN 17
435 YL
OPERATOR MON PANEL POWER TRAIN TEMP
JUMPER
218 BK TRANSMISSION CODING PIN 18
436 OR
OPERATOR MON PANEL POWER TRAIN OIL FILTER
JUMPER
219 BK TRANSMISSION CODING PIN 19
437 BR
OPERATOR MON PANEL FUEL LEVEL TO FUEL
FILTER JUMPER
226
BK
OPERATOR MON PANEL SET POINT SELECT
438
YL
OPERATOR MON PANEL COOLANT TEMP JUMPER
227
BK
TRANSMISSION CODING PIN 37
440
BR
AIR PRESS. GAGE
231
BK
TRANSMISSION SW
441
OR
ENGINE COOLANT TEMP GAGE
236
BK
TRANSMISSION CODING PIN 36
442
GY
HYDRAULIC SYSTEM TEMP GAGE
241
BK
OPERATOR MON PANEL TIME DELAY PIN 3
443
YL
POWER TRAIN TEMP GAGE
242
BK
OPERATOR MON PANEL TIME DELAY PIN 4
444
BU
CONV/RETARDER OIL TEMP GAGE (TRACTOR)
243
BK
OPERATOR MON PANEL TIME DELAY PIN 5
445
GN
CONV /RETARDER OIL TEMP GAGE (SCRAPER)
446
PU
BRAKE OIL TEMPERATURE GAGE
449
BU
SPEEDOMETER SENDER (SIGNAL)
244 BK OPERATOR MON PANEL TIME DELAY PIN 6
Circuit
Number
Color Description
Circuit
Number
Color Description
Monitoring Circuits (Cont.)
Control Circuits
450
YL
TACHOMETER SENDER (+)
702
OR
TRANSMISSION BRAKE SWITCH JUMPER
451
BR
TACHOMETER SENDER (-)
703
BU
TRANSMISSION UP SOLENOID
452
PU
TORQUE CONVERTER
704
GY
TRANSMISSION DOWN SOLENOID
453
PK
SECONDARY STEERING FAULT LAMP
705
PK
TRANSMISSION LOCKUP CLUTCH SOL BASIC
454
GN
RETARDER INDICATOR LAMP
706
BR
TRANSMISSION RETARDER SWITCH
455
YL
CONVERTER TEMP SWITCH TO TIME DELAY
707
PU
TRANSMISSION BED RAISE SWITCH
Accessory Circuits
708
YL
TRANSMISSION HOLD SWITCH
500
BR
WINDSHIELD WIPER - FRONT (PARK)
709
OR
TRANSMISSION PICKUP POWER
501
GN
WINDSHIELD WIPER - FRONT (LOW)
710
GN
TRANSMISSION SPEED PICKUP SIGNAL
502
OR
WINDSHIELD WIPER - FRONT (HIGH)
711
BR
TRANSMISSION LEVER CODE 1
503
BR
WINDSHIELD WIPER - REAR (PARK)
712
WH
TRANSMISSION LEVER CODE 2
504
YL
WINDSHIELD WIPER - REAR (LOW)
713
OR
TRANSMISSION LEVER CODE 3
505
BU
WINDSHIELD WIPER - REAR (HIGH)
714
YL
TRANSMISSION LEVER CODE 4
506
PU
WINDSHIELD WASHER FRONT
715
GN
TRANSMISSION LEVER CODE 5
507
WH
WINDSHIELD WASHER REAR
716
BU
TRANSMISSION LEVER CODE 6
510
YL
WINDSHIELD WASHER-PRIMER
720
PU
TRANSMISSION BRAKE SWITCH
513
OR
AIR CONDITIONER COMPRESSOR
721
BR
TRANSMISSION GEAR CODE 1
514
PU
AIR CONDITIONER CONDENSER MOTOR
722
WH
TRANSMISSION GEAR CODE 2
515
GY
BLOWER MOTOR (HIGH)
723
OR
TRANSMISSION GEAR CODE 3
516
GN
BLOWER MOTOR (MEDIUM)
724
YL
TRANSMISSION GEAR CODE 4
517
BU
BLOWER MOTOR (LOW)
725
GN
TRANSMISSION GEAR CODE 5
519
PK
THERMOSTAT TO DRYER PRESSURE SWITCH
726
BU
TRANSMISSION GEAR CODE 6
520 WH
OPERATOR AIR CONDITIONER SWITCH TO
THERMOSTAT
727 GN STEERING MOTOR RELAY
521
YL
AIR COND SW TO RFGT SW
728
BU
SUPPLEMENTAL STEERING CONTROL SWITCH
522
WH
AIR COND COMPR TO THERMO SW
733
BR
SWITCHING GEAR CODE 1 FRONT
523
BR
WINDSHIELD WIPER-LEFT (PARK)
734
WH
SWITCHING GEAR CODE 2 FRONT
524
BU
WINDSHIELD WIPER-LEFT (LOW)
735
OR
SWITCHING GEAR CODE 3 FRONT
525
GY
WINDSHIELD WIPER-LEFT (HIGH)
736
YL
SWITCHING GEAR CODE 4 FRONT
526
YL
WINDSHIELD WIPER-RIGHT (PARK)
737
GN
SWITCHING GEAR CODE 5 FRONT
527
GN
WINDSHIELD WIPER-RIGHT (LOW)
738
BR
SWITCHING GEAR CODE 1 REAR
528
PK
WINDSHIELD WIPER-RIGHT (HIGH)
739
WH
SWITCHING GEAR CODE 2 REAR
529
WH
WINDSHIELD WASHER-LEFT
740
OR
SWITCHING GEAR CODE 3 REAR
530
OR
WINDSHIELD WASHER-RIGHT
741
YL
SWITCHING GEAR CODE 4 REAR
531
WH
FIRE WARNING HORN
742
GN
SWITCHING GEAR CODE 5 REAR
532
WH
FIRE WARNING LAMP
743
PU
SWITCHING NEUTRAL/RUN SWITCH
533
RD
HEAT SENSOR/TEST SWITCH
744
BU
SWITCHING UP SOLENOID
534
WH
HEAT SENSOR/TEST SWITCH
745
GY
SWITCHING DOWN SOLENOID
535
BU
TRAVEL ALARM TIMER PRESS SWITCH
746
PK
SWITCHING SYNCHRONIZE SOLENOID
536
OR
TRAVEL ALARM TIMER MANUAL OVERRIDE
747
WH
SWITCHING NO SYNCHRONIZE SOLENOID
537
GR
TURN SIGNAL SWITCH TO FLASHER
756
WH
TRANSMISSION LOCKUP CLUTCH SOLENOID
538
BR
HAZARD INDICATOR
761
GY
LIFT KICKOUT SOLENOID SWITCH
539
BU
TURN SIGNAL INDICATOR BASIC/RIGHT
762
YL
BUCKET POSITIONER SOLENOID SWITCH
540
WH
TURN SIGNAL INDICATOR LEFT
763
BU
TORQUE CONVERTER SOLENOID
Lighting Circuits
764 PU
SUPPLEMENTAL STEERING CONTROL SWITCH
(MOTOR GRADER)
600
BK
DASH BASIC
765
OR
APRON SOLENOID (SCRAPER)
601
BK
DASH HIGH
767
WH
ANTISPIN PICKUP POWER
602
BK
DOME
768
OR
ANTISPIN PICKUP TRANSMISSION
603
BK
ROTARY BEACON
769
BU
ANTISPIN PICKUP LEFT
604
BK
STOP
770
GN
ANTISPIN PICKUP RIGHT
605
BU
TURN LEFT
771
PU
ANTISPIN SERVICE BRAKE SWITCH
606
WH
TURN RIGHT
772
BR
ANTISPIN RETARDER SWITCH
607
GN
FLOOD FRONT
773
GY
ANTISPIN SERVOVALVE
608
OR
FLOOD REAR
774
YL
ANTISPIN SOLENOID - LEFT
609
YL
FLOOD SIDE
775
BR
ANTISPIN SOLENOID - RIGHT
610
PU
HEAD LAMP BASIC
611
WH
HEAD LAMP HIGH
612
BR
BACKUP
613
GY
LICENSE PLATE
614
PU
PARK/TAIL/DASH
615
BU
CAB FLOOD/ROPS
616
GN
BUCKET FLOOD
617
OR
TAIL/POSITION LAMP-LEFT (ROADING PACKAGE)
618
BU
TAIL/POSITION LAMP-RIGHT (ROADING PACKAGE)
619
GN
HEAD LAMP LOW
622
WH
FLOODLAMP 3 WAY SWITCH JUMPER
623
WH
FLOODLAMP 3 WAY SWITCH JUMPER
624
GN
FLOODLAMP BOWL
625
GY
COURTESY LAMP
B70453X1
AB
E
AB
E
AB
E
E
A
B
C
GROUND
+V
SIGNAL
TRANSMISSION
SPEED SENSOR
6T2156
LOCKUP
DOWNSHIFT
UPSHIFT
SOLENOID
9P0222
SOLENOID
9P0222
SOLENOID
9P0222
1
2
11
12
13
14
15
16
8
27
28
29
30
31
21
22
23
24
25
26
32
33
34
35
36
GEAR 1
GEAR 2
GEAR 3
GEAR 4
GEAR 5
GND VERIFY
19
18
17
37
9
10
5
4
3
ID CODE 0
ID CODE 1
ID CODE 2
ID CODE 3
+10V
XMSN SPEED
LKUP SOL
DOWN SOL
UP SOL
7
6
20
BODY RAISE
RETARDER
BRAKE
TRANSMISSION
CONTROL
9W0009
37
703-BU
202-BK
707-PU
706-BR
720-PU
202-BK
202-BK
202-BK
219-BK
218-BK
217-BK
227-BK
709-OR
710-GN
705-PK
704-GY
202-BK
726-BU
725-GN
724-YL
723-OR
722-WH
721-BR
1
2
3
4
5
6
20
12
9
8
7
17
19
10
15
14
13
20
408-DR
202-BK
716-BU
715-GN
714-YL
713-OR
712-WH
711-BR
202-BK
308-YL
4
1
2
6
1
2
3
4
5
6
9
7
14
D E
D
D
A
ZZ
+ BATTERY
GROUND
LEVER 1
LEVER 2
LEVER 3
LEVER 4
LEVER 5
GND VERIFY
TO EMS
PANEL
PIN 9
D
202-BK
202-BK
707-PU
D
J
1
2
2
SERVICE BRAKE
SWITCH
3L6306
SECONDARY BRAKE
SWITCH
3T3195
BODY RAISE
SWITCH
9D4734
703-BU
227-BK
709-OR
710-GN
705-PK
704-GY
202-BK
202-BK
726-BU
725-GN
724-YL
723-OR
722-WH
721-BR
721-BR-18
722-WH-18
723-OR-18
724-YL-18
725-GN-18
726-BU-18
202-BK-18
E
E
XX
XX
10
10
A
B
C
E
F
H
G
K
D
J
8
7
6
3
2
1
10
9
4
5
10
TRANSMISSION
GEAR 1
GEAR 2
GEAR 3
GEAR 4
GEAR 5
GND VERIFY
GROUND
NEUTRAL
GROUND
GND VERIFY
SWITCH
7T3419
202-BK
308-YL
711-BR-18
712-WH-18
713-OR-18
714-YL-18
715-GN-18
716-BU-18
202-BK-18
408-DR-18
ZZ
LEVER 1
LEVER 2
LEVER 3
LEVER 4
LEVER 5
3
4
5
8
9
1
2
6
7
10
710-GN
SYSTEM GROUND
DISTRIBUTOR
XMSN SPEED
+24V
SHIFT LEVER
SWITCH
9G8204
SHIFT LEVER SWITCH
R
N
1
2
3
4
5
10
9
8
6
5
4
3
2 1
6
7
8
TEST
N
N
R
1
2
3
4
1
2
5
6
10
9
8
7
6
4
3
2
1
TRANSMISSION SWITCH
D65600
3
4
5
6
8
9
1
2
7
3
4
5
6
8
9
1
2
7
1
2
3
4
5
6
7
8
9
10
11
1
2
3
4
5
6
7
8
9
10
11
777
B92458X1
Connector IDENT.
Harness And/Or
Components
37 Contacts
D - 8WO869
20 Contacts
D - 8W0869
E - 5T0596
Connector IDENT.
Harness And/Or
Components
6 Contacts
A - 5T8868
3 Contacts
E- 5T0596
Transmission Speed Sender
14 Contacts
D - 8W0869
10 Contacts
E- 5T0596
XX - 7T3418
2 Contacts
D - 8W0869
E- 5T0596
Lockup Solenoid
XX - 7T3418
ZZ - 8W0980
Shift Lever Switch
E- 5T0596
Transmission Switch
ZZ - 8W0980
Transmission Control
D - 8W0869
Upshift, Downshift Solenoids
J - 5T1659
1
2
3
4
5
6
7
8
9
10
11
COMPONENT IDENTIFICATION
1. Transmission Control.
2. Shift Lever Switch.
3. Transmission Switch.
4. Transmission Speed Sender.
5. Upshift and Downshift Solenoids.
6. Lockup Solenoid.
7. Service Brake Switch.
8. Secondary Brake Switch.
9. Body Raise Switch.
IDENT HARNESS AS.
A 5T8868
D 8W0869
E 5T0596
J 5T1659
XX 7T3418
ZZ 8W0980
