©
2001 Caterpillar
All Rights Reserved
Printed in U.S.A.
SENR9628
November 2001
3126 Truck Engine
Electrical System
1BW1-UP
TOP VIEW
LEFT SIDE VIEW
ECM
Ground
Strap
Electronic Control
Module (ECM)
Electronic Control
Module (ECM)
ECM Engine
Harness
Connector
J2/P2
ECM Vehicle
Harness
Connector
J1/P1
Injector
Harness
Grommet
Timing
Calibration
Probe
Connector
J24/P24
Timing Calibration
Probe Connector
J24/P24
Injector
Harness
Grommet
Injection
Actuation
Pressure
Sensor
Ground
Stud
Injection
Actuation
Pressure
Sensor
Intake Manifold
Air Temperature
Sensor
Unit
Injector
Cylinder #6
654321
Intake Manifold
Air Temperature
Sensor
Engine Oil
Temperature
Sensor
Engine Oil
Temperature
Sensor
High
Pressure
Pump
High
Pressure
Pump
Boost
Pressure
Sensor
Coolant
Temperature
Sensor
Injection Actuation
Pressure Control
Valve (IAPCV)
Injection Actuation
Pressure Control
Valve (IAPCV)
Top
Speed/Timing
Sensor
Bottom
Speed/Timing
Sensor
*
*
Inlet Air Heater
Lamp Connector
P40
Inlet Air
Heater
INPUT SIGNAL WIRES TO ECM
OUTPUT SIGNAL WIRES FROM ECM
SENSOR SUPPLY VOLTAGE
(+) BATTERY SUPPLY WIRES
SIGNAL PLUS
(-) BATTERY / SENSOR RETURN
SIGNAL MINUS
P2 J2
J51 P51
C
B
A
ENGINE OIL
TEMPERATURE
SENSOR
E795-YL
993-BR
997-OR
ENGINE OIL TEMP
SENSOR COMMON
+5V
WH
BK
OR
INTAKE MANF AIR TEMP
SENSOR COMMON
+5V
J10 P10
C967-BU
993-BR
997-OR
INTAKE MANIFOLD
AIR TEMPERATURE
SENSOR
A
B
C
WH
BK
OR
N/O
RELAY
J37
J36 P36
J24 P24
J34 P34
J33 P33
J32 P32
J31 P31
J30 P30
J29 P29
BOOST PRESSURE
SENSOR COMMON
+5V
BOOST
PRESSURE
SENSOR
INJECTION
ACTUATION
PRESSURE
SENSOR
CYL
NO.1
CYL
NO.2
CYL
NO.3
CYL
NO.4
CYL
NO.5
A706-GY
A726-OR
A705-BU
A725-YL
A704-GN
A724-WH
C
B
A
A746-PK
993-BR
997-OR
1
2
P3 J3
INJECTION ACTUATION
TIMING CALIBRATION
PROBE CONNECTOR
PRESSURE CONTROL VALVE
A
B
INLET AIR
HEATER
INLET AIR
HEATER
GROUND STRAP
INLET AIR
HEATER
E965-BU
E966-YL
CYL
NO.6
E963-BK
E964-WH
TO ENGINE CYL HEAD
(NOT CYL HEAD GND STUD)
TO +BATTERY
2
1
A703-BR
A723-OR
A702-PU
A722-YL
B
A
B
A
A
B
A
B
A
B
A
B
A
B
WH
BK
OR
INJECTOR HARNESS GROMMET
D796-OR
D812-RD
469
468
GN
YL
OR
TO ECM
MOUNTING
BOLT
D797-PK
D798-BK
6
5
12
11
18
17
22
21
28
27
34
33
INJECTOR 1
INJECTOR COMMON 1
INJECTOR 2
INJECTOR COMMON 2
INJECTOR 3
INJECTOR COMMON 3
INJECTOR 4
INJECTOR COMMON 4
INJECTOR 5
INJECTOR COMMON 5
INJECTOR 6
INJECTOR COMMON 6
VEHICLE SPEED OUT+
VEH SP IN+/TDC PROBE+
VEH SP IN-/TDC PROBE-
VEHICLE SPEED OUT-
INJ ACTUATION PRESS. CONT VALVE
IAP CONT VALVE COMMON
ENG SP/TMG #1-
ENG SP/TMG #1+
ECM GND STRAP
ELECTRONIC CONTROL MODULE (ECM)
ELECTRONIC CONTROL MODULE (ECM)
ENG SP/TMG #2-
ENG SP/TMG #2+
BOOST PRESSURE
INJ ACTUATION PRESS.
COOLANT TEMP
INTAKE MANF AIR TEMP
OIL TEMP
SENSOR COMMON
+5V
INLET AIR HEATER
37
29
25
15
3
23
24
14
2
32
7
16
26
30
36
38
20
35
31
40
39
4
10
19
13
1
8
9
A
INJ ACTUATION PRESS.
SENSOR COMMON
+5V
GN
YL
OR
B
TOP SPEED/TIMING SENSOR
ENGINE SPEED / TIMING -
ENGINE SPEED / TIMING +
ENGINE SPEED / TIMING -
ENGINE SPEED / TIMING +
P35 J35
J9 P9
A701-GY
A721-WH
J4 P4
B
D841-GN
993-BR
997-ORA
B
C
A
A701-GY
A721-WH
A702-PU
A722-YL
A703-BR
A723-OR
A704-GN
A724-WH
A705-BU
A725-YL
A706-GY
A726-OR
D784-BU
D810-PU
D811-YL
D785-GN
D797-PK
D798-BK
E963-BK
E964-WH
COOLANT TEMP
SENSOR COMMON
+5V
995-BU
993-BR
997-OR
COOLANT
TEMPERATURE
SENSOR
A
B
C
D812-RD
D796-OR
D812-RD
D796-OR
BOTTOM SPEED/TIMING SENSOR
P40
APC
CONNECTED TO
LAV HARNESS OR
APC HARNESS
LAV
P37
J21 P21
E965-BU
E966-YL
A746-PK
D841-GN
995-BU
C967-BU
E795-YL
993-BR
997-OR
D796-OR
A
B
J1
P6 J1
P1J2
P1 J1
P1J1
469
468
B
A
35
+8V
30
MULTI-FUNCTION SENSOR COMMON
37
THROTTLE POSITION
EXHAUST BRAKE
40
XMSN NEUTRAL SW
38
SERVICE BRAKE SW #1
14
2
FAST IDLE ENABLE SW
29
SENSOR COMMON
CHECK ENGINE LAMP
22
7
ATA DATA LINK+ (J1587)
1
ATA DATA LINK- (J1587)
VEHICLE SPEED IN+
18
5
-BATTERY
28
+BATTERY
4
-BATTERY
6
+BATTERY
3
NOT USED
8
NOT USED
9
NOT USED
11
NOT USED
10
NOT USED
12
NOT USED
13
NOT USED
15
FROM (J1)
ELECTRONIC
CONTROL MODULE
(ENGINE)
FROM (J1)
ELECTRONIC
CONTROL MODULE
(ENGINE)
NOT USED
16
NOT USED
17
NOT USED
19
NOT USED
20
NOT USED
21
NOT USED
23
NOT USED
24
NOT USED
25
NOT USED
26
NOT USED
27
NOT USED
31
NOT USED
32
NOT USED
33
NOT USED
34
NOT USED
36
NOT USED
39
NOT USED
+8V
MULTI-FUNCTION SENSOR COMMON
LAV INTERFACE HARNESS
THROTTLE POSITION
EXHAUST BRAKE
XMSN NEUTRAL SW
SERVICE BRAKE SW #1
FAST IDLE ENABLE SW
SENSOR COMMON
CHECK ENGINE LAMP
ATA DATA LINK+ (J1587)
ATA DATA LINK- (J1587)
VEHICLE SPEED IN+
-BATTERY
+BATTERY
-BATTERY
+BATTERY
570
35
571
469
468
30
572
37
573
40
574
38
14
575
89
2
577
29
22
578
586
7
585
1
18
579
581
5
580
28
581
4
580
6
K
L
M
N
P
R
S
T
U
V
W
X
Y
Z
E
A
A
F
B
C
D
TO VEHICLE
COMPONENTS
TO
POWER PACK
INTERFACE
ENGINE
BULKHEAD
D
E
F
G
H
J
K
L
M
N
P
R
S
T
U
V
W
X
Y
Z
E
A
A
F
B
C
D
D
E
F
G
H
J
3
8
9
11
10
12
13
15
16
17
19
20
21
23
24
25
26
27
31
32
33
34
36
39
+8V
MULTI-FUNCTION SENSOR COMMON
APC INTERFACE HARNESS
THROTTLE POSITION
EXHAUST BRAKE
XMSN NEUTRAL SW
SERVICE BRAKE SW #1
FAST IDLE ENABLE SW
SENSOR COMMON
CHECK ENGINE LAMP
ATA DATA LINK+ (J1587)
ATA DATA LINK- (J1587)
VEHICLE SPEED IN+
-BATTERY
+BATTERY
-BATTERY
+BATTERY
570
35
571
30
572
37
573
40
574
38
14
575
576
2
577
29
22
578
142
7
151
1
18
579
581
5
580
28
581
4
580
6
K
L
M
N
P
R
S
T
U
V
W
X
Y
Z
e
A
a
f
b
c
D
TO VEHICLE
COMPONENTS
TO
POWER PACK
INTERFACE
POWER PACK
BULKHEAD
d
B
C
E
F
G
H
J
K
L
M
N
P
R
S
T
U
V
W
X
Y
Z
e
A
a
f
b
c
D
d
B
C
E
F
G
H
J
3
8
9
11
10
12
13
15
16
17
19
20
21
23
24
25
26
27
31
32
33
34
36
39
B
C
B
C
469
468
RIGHT SIDE VIEW
Inlet Air
Heater
Relay
Inlet Air
Heater
Ground
Strap
Inlet Air
Heater
AB
CONNECTED TO
LAV HARNESS OR
APC HARNESS
