Caterpillar identifies different wires with eleven different solid colors. Table 1 lists the color codes of the wiring.
| 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
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.
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| Illustration 1 | g01329087 |
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Rear view (1) Terminal box | |
The terminal box contains the Electronic Control Module (ECM). The electrical connectors for the terminal box are located between the terminal box and the engine.
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| Illustration 2 | g01957121 |
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Rear view The cover of terminal box (1) is not shown. (2) Terminal box (3) ECM (4) P2 connector (5) P1 connector (6) Panel light switch (7) J7 connector for the main wiring group (8) J8 connector for the detonation sensors (9) J9 connector for the main wiring group (10) J6 connector for the customer (11) Connector for the service tool (12) Emergency stop button (typical location) (13) Connector for the left side ignition (14) Connector for the right side ignition (15) Integrated Temperature Sensing Module (ITSM) | |
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| Illustration 3 | g01957243 |
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The is located on left side of the engine. (16) Power distribution box (17) 2.0 amp circuit breaker for the engine control (18) 10 amp circuit breaker for the customer (19) 35 amp circuit breaker for the engine (20) 2.5 amp circuit breaker for the start command from the ECM (21) Positive terminal for the connection of the engine's power supply (22) 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 junction 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 breakers
Those conditions can contribute to the following difficulties with operation:
- Unstable engine performance
- Interruption of communication between the engine electronic control module (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 shutdown
The new design now uses new brackets for shock mounting of the power distribution box. Check the shock mounting for the current design.