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 | g01076788 |
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The connectors on the terminal box connect the Electronic Control Module (ECM) to various engine controls, sensors, actuators, etc. (1) Emergency stop button (2) Service tool connector J23 for the Caterpillar Electronic Technician (3) Connector for the 168-2028 Wiring Harness (4) Connectors J16/P16 for the harness to the fuel metering valve (5) This connector is not used. (6) Connectors J14/P14 for the wiring to the starting motor (7) Connectors J13/P13 for the wiring to the gas shutoff valve (8) Connectors J12/P12 for the harness to the analog sensors (9) Connectors J11/P11 for the harness to the detonation sensors (10) Connectors J10/P10 for the harness to the speed/timing sensor, throttle actuator, and oxygen buffer (if equipped) (11) Harness to the ignition transformers (12) Connectors J5/P5 for the harness to the Integrated temperature sensing module (13) This connector is not used. (14) Connectors J9/P9 for the wiring to the customer's connections | |
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| Illustration 2 | g01076361 |
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Components inside the terminal box (15) Electronic Control Module (ECM) (16) ECM connector P2 (17) ECM connector P1 (18) Ground strap for the ECM (19) P50 connector for calibration of the speed/timing sensor (20) 16 amp circuit breaker for the engine (21) 6 amp circuit breaker for the switched +Battery | |