826148R 1 Mercury SERVICE MANUAL

Table 1
Color Codes for Wiring
Code Color
BK Black
BR Brown
BU Blue
GN Green
GY Gray
OR Orange
PK Pink
PU Purple
RD Red
WH White
YL Yellow In addition to the color, the entire length of each wire is stamped with a specific circuit number that is repeated on every 50 mm (2 inch) of the wire. The actual wires are identified on the schematic.For example, a code of J011-RD on the schematic identifies a red wire that is stamped with the circuit number J011. This particular wire is the engine harness wire for the primary signal of the transformer in the number one cylinder. For all Caterpillar engine harnesses with electronic ignition systems, the code of J011-RD identifies the wire for the primary signal of the transformer in the number one cylinder.The schematic also identifies the size of the wire. The size or gauge of the wire is called the American Wire Gauge (AWG). Unless the schematic specifies a different size, you may assume that the wire is 16 AWG.Terminal Box and Electrical Connectors
The two possible configurations for the control system are with the optional Auxiliary Sensing Module (ASM) and without the optional ASM.
Illustration 1 g01288540
Rear view
This view is without the optional Auxiliary Sensing Module (ASM). The cover of terminal box (1) is not shown.
(1) Terminal box
(2) Master Electronic Control Module (ECM)
(3) P2 connector
(4) P1 connector
(5) Slave ECM
(6) P3 connector
(7) P4 connector
(8) Integrated Temperature Sensing Module (ITSM)
(9) Emergency stop button
Illustration 2 g01288541
Left rear corner of the engine without the optional ASM
(1) Terminal box
(8) ITSM
(10) Service tool connector
(11) J6 connector for the customer
(12) J7 connector for the main wiring group
(13) J8 connector for the detonation sensors
(14) J9 connector for the ASM
(15) Battery disconnect switch (if equipped)
Illustration 3 g01288542
Rear view
This view is with the optional Auxiliary Sensing Module (ASM). The cover of terminal box (1) is not shown.
(1) Terminal Box
(2) Master ECM
(3) P2 connector
(4) P1 connector
(5) Slave ECM
(6) P3 connector
(7) P4 connector
(8) Integrated Temperature Sensing Module (ITSM)
(9) Emergency stop button
(10) J11 Service tool connector
(11) P6 connector for the customer
(12) P7 connector for the main wiring group
(13) P8 connector for the detonation sensors
(14) P9 connector for the ASM
(15) ASM
(16) Panel light switch
(17) P5 connector Power Distribution Box
Illustration 4 g01541596
The power distribution box is located on left side of the engine.
(18) Power distribution box
(19) 2.5 amp circuit breaker for the engine control
(20) 10 amp circuit breaker for the customer
(21) 35 amp circuit breaker for the engine
(22) 2.5 amp circuit breaker for the start command from the master ECM
(23) Positive terminal for the connection of the engine's power supply
(24) Negative terminal for the connection of the engine's power supply The power distribution box contains all of the circuit breakers for the engine. The power distribution box also contains the magnetic switches for the electric starting motors.The mounting of the power distribution box and the routing of the wiring within the box has been improved. The improvements will extend the service life of the wiring and of the circuit breakers. The improvements will help to prevent the following conditions that are related to vibration:
Abrasion of the insulation on the wiring within the box
Damage to the posts for the wiring to the circuit breakers
Damage to the internal parts of the circuit breakersThose conditions can contribute to the following difficulties with operation:
Unstable engine performance
Interruption of communication between the engine ECM, the fuel metering valve, the actuator for the compressor bypass, and the throttle actuator
Intermittent loss of power to the ECM
Intermittent diagnostic codes for conditions such as engine overspeed and lack of communication between electronic components
Unexpected engine shutdownThe new design now uses new brackets for shock mounting of the power distribution box. Check the shock mounting for the current design.