For ICM (Individual Clutch Modulation) Type Transmission
SENR3302
January 1986
621E & 623E Wheel Tractor Scraper
Power Train Electrical System
621E:
Tractor 6AB1-UP
623E:
Tractor 6CB1-UP
Scraper 6BB1-UP Scraper 6DB1-UP
Electronic Powershift Transmission Control System
For 621E & 623E Wheel Tractor-Scrapers Equipped With
©
1986 Caterpillar
All Rights Reserved
Printed in U.S.A.
Circuit
Number
Color Description
Circuit
Number
Color Description
101
RD
BATTERY
313
GY
STARTER NO. 2 TO
102
BU
HEAD LAMP
DIAGNOSTIC/RESISTOR TO
103
YL
DOME/DASH LAMP/PARK, TAIL LAMP
DIAGNOSTIC
105
BR
KEY SWITCH
314
PU
STARTER RELAY NO. 2 OUTPUT
106
WH
MAIN POWER RELAY/INPUT
321
BR
BACKUP ALARM/LAMP
107
WH
ENGINE SHUT DOWN
322
GY
WARNING HORN (FORWARD)
108
BU
MISC WIPER, DOME LAMP, CIGAR
323
WH
FUEL TRANSFER PUMP POWER
LIGHTER
324
BU
DIFFERENTIAL LOCKUP SOLENOID
109
OR
ALTERNATOR
325
PK
FUEL PUMP RELAY OIL PRESS.
110
GN
WINDSHIELD WIPER SWITCH (RIGHT)
SWITCH
111
YL
WINDSHIELD WIPER SWITCH (LEFT)
326
PU
KEY SWITCH “C” TERMINAL
112
PU
MAIN POWER RELAY/OUTPUT
327
PK
SHUTDOWN SOLENOID
113
OR
OPERATOR MONITOR PANEL
328
RD
SHUTDOWN MODULE “OFF”
114
GN
WARNING HORN (FORWARD)
115
PK
FLOOD LAMP (FRONT)
400
GN
SERVICEMETER SWITCH
116
BR
FLOOD LAMP (REAR)
403
GN
ALTERNATOR (R) TERMINAL
117
YL
FLOOD LAMP (SIDE)
404
YL
OPERATOR MON PANEL HYDRAULIC
118
GY
WINDSHIELD WIPER SWITCH (FRONT)
OIL TEMP
119
PK
WINDSHIELD WIPER SWITCH (REAR)
405
GY
OPERATOR MON PANEL OIL
120
YL
CONVERTER (24 V to 12 V)
PRESSURE
121
YL
BACKUP ALARM/LAMP/TRAVEL
406
PU
OPERATOR MON PANEL COOLANT
ALARM TIMER
TEMPERATURE
122
BU
AIR DRYER
407
PK
OPERATOR MON PANEL
123
WH
GAGES (SERVICEMETER, TORQUE
CONV/RETARDER OIL TEMP
CONV SOLENOID)
408
WH
OPERATOR MON PANEL BRAKE
124
GN
AIR CONDITIONER
PRESS. (AIR)
125
OR
FUEL TRANSFER PUMP
409
OR
OPERATOR MON PANEL NEUTRAL
126
PK
TRANSMISSION CONTROL
410
WH
OPERATOR MON PANEL FAULT
127
OR
CAB FLOOD LAMP
ALARM
128
PK
KICKOUT SOLENOID SWITCH
411
PK
OPERATOR MON PANEL MASTER
129
BU
CIGAR LIGHTER
FAULT LAMP
130
GN
STOP LAMP
412
BU
OPERATOR MON PANEL COOLANT FLOW
131
BR
FIRE CONTROL-OPERATOR WARNING
413
BR
OPERATOR MON PANEL FUEL
132
PK
ANTISPIN CONTROL
PRESSURE
133
OR
PROGRAMMED ELECTRONIC ENG
414
PK
OPERATOR MON PANEL LOW FUEL
CONT SOLENOID
415
GN
OPERATOR MON PANEL TEST SWITCH
134
PK
PROGRAMMED ELECTRONIC ENG
416
OR
SECONDARY STEERING SWITCH
CONT LOGIC
417
GY
PRIMARY STEERING SWITCH
136
GN
SUPPLEMENTAL STEERING
418
YL
OPERATOR MON PANEL OIL
137
RD
STEERING MOTOR INDICATOR
PRESSURE (HIGH SETTING)
138
GN
AUTOMATIC LUBE PUMP (TRUCK)
419
YL
OPERATOR MON PANEL PARKING
141
PK
AUXILIARY HEATER
BRAKE
420
OR
OPERATOR MON PANEL FUEL
200
BK
MAIN CHASSIS
FILTER/LOW ACCUM PRESS.
201
BK
OPERATOR MONITOR PANEL
421
BU
OPERATOR MON PANEL FAULT LAMP
202
BK
TRANSMISSION CONTROL
(SCRAPER)
203
BK
CHASSIS DIAGNOSTIC
422
YL
OPERATOR MON WARNING HORN
204
BK
OPERATOR MONITOR PANEL
(SCRAPER)
(SCRAPER)
423
GY
OPERATOR MON PANEL TEST SWITCH
205
BK
INSTRUMENT
(SCRAPER)
206
BK
BATTERY SIDE OF DISCONNECT
424
GY
OPERATOR MON PANEL POWER
207
BK
STARTER DIAGNOSTIC
TRAIN TEMPERATURE
212
BK
ANTISPIN CODING PIN 16
425
PK
OPERATOR MON PANEL POWER
213
BK
ANTISPIN CODING PIN 17
TRAIN OIL LEVEL
214
BK
ANTISPIN CODING PIN 18
426
BR
OPERATOR MON PANEL POWER
215
BK
ANTISPIN CODING PIN 19
TRAIN OIL FILTER
216
BK
ANTISPIN CODING PIN 20
427
GN
OPERATOR MON PANEL POWER
217
BK
TRANSMISSION CODING PIN 17
TRAIN OIL FILTER JUMPER
218
BK
TRANSMISSION CODING PIN 18
428
OR
OPERATOR MON PANEL
219
BK
TRANSMISSION COOING PIN 19
TRANSMISSION OIL TEMP
226
BK
OPERATOR MON PANEL SET POINT
429
YL
OPERATOR MON PANEL BRAKE OIL
SELECT
TEMPERATURE
227
BK
TRANSMISSION CODING PIN 37
431
GN
OPERATOR MON PANEL LOW
231
BK
TRANSMISSION SW
TRANSFER PUMP PRESS.
236
BK
TRANSMISSION CODING PIN 36
432
PK
OPERATOR MON PANEL BRAKE
241
BK
OPERATOR MON PANEL TIME
PRESSURE (OIL)
DELAY PIN 3
433
BU
OPERATOR MON PANEL BRAKE
242
BK
OPERATOR MON PANEL TIME
PRESS. (OIL) JUMPER
DELAY PIN 4
434
BU
OPERATOR MON PANEL POWER
243
BK
OPERATOR MON PANEL TIME
TRAIN TEMP JUMPER
DELAY PIN 5
435
YL
OPERATOR MON PANEL POWER
244
BK
OPERATOR MON PANEL TIME
TRAIN TEMP JUMPER
DELAY PIN 6
436
OR
OPERATOR MON PANEL POWER
TRAIN OIL FILTER JUMPER
301
BU
STARTER NO. 1 SOLENOID
437
BR
OPERATOR MON PANEL FUEL LEVEL
TO RESISTOR
TO FUEL FILTER JUMPER
302
OR
STARTER NO. 1 TO
438
YL
OPERATOR MON PANEL COOLANT
DIAGNOSTIC/RESISTOR TO
TEMP JUMPER
DIAGNOSTIC
440
BR
AIR PRESS. GAGE
304
WH
STARTER RELAY NO. 1 OUTPUT
441
OR
ENGINE COOLANT TEMP GAGE
306
GN
STARTER RELAY COIL/NEUTRAL
442
GY
HYDRAULIC SYSTEM TEMP GAGE
START SWITCH
443
YL
POWER TRAIN TEMP GAGE
308
YL
MAIN POWER RELAY COIL
444
BU
CONV/RETARDER OIL TEMP GAGE
310
PU
ETHER SWITCH TO ETHER SOLENOID
(TRACTOR)
311
WH
ETHER SOLENOID TO TEMPERATURE
445
GN
CONV/RETARDER OIL TEMP GAGE
SWITCH
(SCRAPER)
312
PK
STARTER NO. 2 SOLENOID
446
PU
BRAKE OIL TEMPERATURE GAGE
TO RESISTOR
447
PK
FUEL LEVEL GAGE
Machine Basic Circuits
Power Distribution Circuits
Machine Basic Circuits (Cont.)
Monitoring Circuits
Ground Circuits
Ident. Components
1 Hold Switch.
2 Shift Lever Switch.
3 Tractor Transmission Control.
4 Tractor Transmission Switch.
5 Tractor Upshift and Downshift Solenoids.
6 Transmission Speed Sender.
Connectors Ident.
Harness and/or
Components
D-**
Transmission Control
D-**
WW-8W3380
14 Contacts
D-**
WW-6G9811
WW-6G9811
Shift Lever Switch
D-**
V-7T3418
V-7T3418
Transmission Switch (Tractor)
3 Contacts
D-**
Transmission Speed Sender
2 Contacts
D-**
Upshift, Downshift Solenoids
**USE 6G8082 ON 621E AND 5T1524 ON 623E FOR HARNESS D.
37 Contacts
10 Contacts
Circuit
Number
Color Description
Circuit
Number
Color Description
449
BU
SPEEDOMETER SENDER (SIGNAL)
709
OR
TRANSMISSION PICKUP POWER
450
YL
TACHOMETER SENDER (+)
710
GN
TRANSMISSION SPEED PICKUP SIGNAL
451
BR
TACHOMETER SENDER (-)
711
BR
TRANSMISSION LEVER CODE 1
452
PU
TORQUE CONVERTER
712
WH
TRANSMISSION LEVER CODE 2
453
PK
SECONDARY STEERING FAULT LAMP
713
OR
TRANSMISSION LEVER CODE 3
454
GN
RETARDER INDICATOR LAMP
714
YL
TRANSMISSION LEVER CODE 4
455
YL
CONVERTER TEMP SWITCH TO TIME
715
GN
TRANSMISSION LEVER CODE 5
DELAY
716
BU
TRANSMISSION LEVER CODE 6
720
PU
TRANSMISSION BRAKE SWITCH
500
BR
WINDSHIELD WIPER - FRONT (PARK)
721
BR
TRANSMISSION GEAR CODE 1
501
GN
WINDSHIELD WIPER - FRONT (LOW)
722
WH
TRANSMISSION GEAR CODE 2
502
OR
WINDSHIELD WIPER - FRONT (HIGH)
723
OR
TRANSMISSION GEAR CODE 3
503
BR
WINDSHIELD WIPER - REAR (PARK)
724
YL
TRANSMISSION GEAR CODE 4
504
YL
WINDSHIELD WIPER - REAR (LOW)
725
GN
TRANSMISSION GEAR CODE 5
505
BU
WINDSHIELD WIPER - REAR (HIGH)
726
BU
TRANSMISSION GEAR CODE 6
506
PU
WINDSHIELD WASHER FRONT
727
GN
STEERING MOTOR RELAY
507
WH
WINDSHIELD WASHER REAR
728
BU
SUPPLEMENTAL STEERING CONTROL
510
YL
WINDSHIELD WASHER-PRIMER
SWITCH
513
OR
AIR CONDITIONER COMPRESSOR
733
BR
SWITCHING GEAR CODE 1 FRONT
514
PU
AIR CONDITIONER CONDENSER
734
WH
SWITCHING GEAR CODE 2 FRONT
MOTOR
735
OR
SWITCHING GEAR CODE 3 FRONT
515
GY
BLOWER MOTOR (HIGH)
736
YL
SWITCHING GEAR CODE 4 FRONT
516
GN
BLOWER MOTOR (MEDIUM)
737
GN
SWITCHING GEAR CODE 5 FRONT
517
BU
BLOWER MOTOR (LOW)
738
BR
SWITCHING GEAR CODE 1 REAR
519
PK
THERMOSTAT TO DRYER PRESSURE
739
WH
SWITCHING GEAR CODE 2 REAR
SWITCH
740
OR
SWITCHING GEAR CODE 3 REAR
520
WH
OPERATOR AIR CONDITIONER SWITCH
741
YL
SWITCHING GEAR CODE 4 REAR
TO THERMOSTAT
742
GN
SWITCHING GEAR CODE 5 REAR
521
YL
AIR COND SW TO RFGT SW
743
PU
SWITCHING NEUTRAL/RUN SWITCH
522
WH
AIR COND COMPR TO THERMO SW
744
BU
SWITCHING UP SOLENOID
523
BR
WINDSHIELD WIPER-LEFT (PARK)
745
GY
SWITCHING DOWN SOLENOID
524
BU
WINDSHIELD WIPER-LEFT (LOW)
746
PK
SWITCHING SYNCHRONIZE SOLENOID
525
GY
WINDSHIELD WIPER-LEFT (HIGH)
747
WH
SWITCHING NO SYNCHRONIZE
526
YL
WINDSHIELD WIPER-RIGHT (PARK)
SOLENOID
527
GN
WINDSHIELD WIPER-RIGHT (LOW)
756
WH
TRANSMISSION LOCKUP CLUTCH
528
PK
WINDSHIELD WIPER-RIGHT (HIGH)
SOLENOID
529
WH
WINDSHIELD WASHER-LEFT
761
GY
LIFT KICKOUT SOLENOID SWITCH
530
OR
WINDSHIELD WASHER-RIGHT
762
YL
BUCKET POSITIONER SOLENOID
531
WH
FIRE WARNING HORN
SWITCH
532
WH
FIRE WARNING LAMP
763
BU
TORQUE CONVERTER SOLENOID
533
RD
HEAT SENSOR/TEST SWITCH
764
PU
SUPPLEMENTAL STEERING CONTROL
534
WH
HEAT SENSOR/TEST SWITCH
SWITCH (MOTOR GRADER)
535
BU
TRAVEL ALARM TIMER PRESS SWITCH
765
OR
APRON SOLENOID (SCRAPER)
536
OR
TRAVEL ALARM TIMER MANUAL
767
WH
ANTISPIN PICKUP POWER
OVERRIDE
768
OR
ANTISPIN PICKUP TRANSMISSION
537
SR
TURN SIGNAL SWITCH TO FLASHER
769
BU
ANTISPIN PICKUP LEFT
538
BR
HAZARD INDICATOR
770
GN
ANTISPIN PICKUP RIGHT
539
BU
TURN SIGNAL INDICATOR BASIC/RIGHT
771
PU
ANTISPIN SERVICE BRAKE SWITCH
540
WH
TURN SIGNAL INDICATOR LEFT
772
BR
ANTISPIN RETARDER SWITCH
773
GY
ANTISPIN SERVOVALVE
600
BR
DASH BASIC
774
YL
ANTISPIN SOLENOID - LEFT
601
GY
DASH HIGH
775
BR
ANTISPIN SOLENOID - RIGHT
602
WH
DOME
603
PK
ROTARY BEACON
604
OR
STOP
605
YL
TURN LEFT
606
GY
TURN RIGHT
607
PK
FLOOD FRONT
608
GN
FLOOD REAR
609
YL
FLOOD SIDE
610
OR
HEAD LAMP BASIC
611
PU
HEAD LAMP HIGH
612
GY
BACKUP
613
PK
LICENSE PLATE
614
PU
PARK/TAIL/DASH
615
YL
CAB FLOOD /ROPS
616
BU
BUCKET FLOOD
617
BR
TAIL/POSITION LAMP-LEFT (ROADING
PACKAGE)
618
YL
TAIL/POSITION LAMP-RIGHT (ROADING
PACKAGE)
619
SR
HEAD LAMP LOW
622
PU
FLOODLAMP 3 WAY SWITCH JUMPER
623
BU
FLOODLAMP 3 WAY SWITCH JUMPER
624
YL
FLOODLAMP BOWL
625
BK
COURTESY LAMP
702
OR
TRANSMISSION BRAKE SWITCH JUMPER
703
BU
TRANSMISSION UP SOLENOID
704
GY
TRANSMISSION DOWN SOLENOID
705
PK
TRANSMISSION LOCKUP CLUTCH SOL BASIC
706
BR
TRANSMISSION RETARDER SWITCH
707
PU
TRANSMISSION BED RAISE SWITCH
708
YL
TRANSMISSION HOLD SWITCH
Control Circuits (Cont.)
Accessory Circuits
Lighting Circuits
Control Circuits
Monitoring Circuits (Cont.)
1
2
3
4
5
7
8
6
126-PK+ BATTERY 1 16 112-PU-10
MAIN RELAY
3T0376
24 V SOURCE
TRANSMISSION
10 A
FUSE
3K8782
D W
37
E621EPT
2
202-BK 20GROUND
31
32
33
34
35
88
28
29
30
D
HOLD SWITCH 708-YL
202-BK
HOLD SWITCH
9G2795
16
11
12
13
14
15
202-BK
716-BU
711-BR
712-WH
713-OR
714-YL
715-GN
9
6
1
2
3
4
5
202-BK-18
716-BU-18
711-BR-18
712-WH-18
713-OR-18
714-YL-18
715-GN-18
D WW
GND VERIFY
LEVER 1
LEVER 2
LEVER 3
LEVER 4
LEVER 5
GND VERIFY
LEVER 1
LEVER 2
LEVER 3
LEVER 4
LEVER 5
GROUND
WW
1
3
4
5
8
9
2
6
7
10
NEUTRAL
SHIFT LEVER SWITCH
9G8204
470-PK-187470-PK
D W
9
37
NEUTRAL/START CONTROL PIN 4
14
10
ID CODE 2
ID CODE 1
ID CODE 0
37
17
18
19
36
ID CODE 3 *
202-BK
GEAR 1
GEAR 2
GEAR 3
GEAR 4
GEAR 5
GND VERIFY
21
22
23
24
25
26
721-BR
722-WH
723-OR
724-YL
725-GN
726-BU
A
B
C
E
F
H
G
721-BR-18
722-WH-18
723-OR-18
724-YL-18
725-GN-18
726-BU-18
202-BK-18
10
10
D V
V
8
7
6
3
2
1
4
10
5
9
GEAR 1
GEAR 2
GEAR 3
GEAR 4
GEAR 5
GND VERIFY
GROUND
6
7
20
27
9
10
10 V
XMSN SPEED
709-OR
710-GN
GROUND
SIGNAL
V
A
C
B
202-BK
D
703-BU
D
D
B A B A
704-GY
202-BK
3
4
5
UP SOL
DOWN SOL
TRANSMISSION
CONTROL
9W0009
UNLESS OTHERWISE SPECIFIED:
ALL WIRE IS 16 GAGE.
* PIN 37 IS GROUNDED ON 621E ONLY.
DOWNSHIFT
SOLENOID
9P0222
UPSHIFT
SOLENOID
9P0222
TRANSMISSION
SPEED SENDER
7T6337
TRANSMISSION SWITCH
(TRACTOR)
7T3419
D66002
8
7
6
5
4
3
2
1
R
N
TEST
10
9
8 7
6 4
3
2 1
R
N
1
2
3
4
5
6
7
8
10
9
6
8
5
4
3
2
1
SHIFT LEVER SWITCH
TRANSMISSION SWITCH
IDENT HARNESS AS.
D **
V 7T3418
w 8W3380
ww 6G9811
** USE 6G8082FOR 621E
AND 5T1524 FOR 623E
E620HID
1
2
3
4
5
6
7
8
3
4
5
6
1
2
1
2
3
4
5
6
7
8
3
4
5
6
1
2
