Diagnostic Trouble Code List
Use the instrument cluster or use the Caterpillar Electronic Technician (Cat ET) in order to determine the diagnostic trouble codes for the Transmission ECU. After determining the diagnostic trouble codes, refer to the corresponding test procedure for more information. Perform the procedure that corresponds with the correct diagnostic trouble code. The following table is a list of possible diagnostic trouble codes for the ECU.
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| Diagnostic Trouble Codes For The CX Series Transmissions | |
|---|---|
| For troubleshooting, see the procedure with the same "SPN" and "FMI". | |
| "SPN"/"CID" | Description |
| SPN 91 Accelerator Pedal | |
| FMI 9 | Abnormal update |
| FMI 19 | Data error |
| SPN 126 Transmission Oil Filter Differential Pressure Sensor | |
| FMI 3 | Voltage above normal |
| FMI 16 | Data valid but above normal operating range (moderate severity) |
| SPN 158 Battery Potential (Keyswitch) | |
| FMI 2 | Data that is erratic, intermittent, or incorrect |
| SPN 161 Transmission Input Shaft Speed | |
| FMI 8 | Abnormal frequency |
| SPN 168 Electrical System Voltage | |
| FMI 3 | Voltage above normal |
| FMI 4 | Voltage below normal |
| SPN 177 Temperature Sensor (Transmission Oil) | |
| FMI 3 | Voltage above normal |
| FMI 4 | Voltage below normal |
| FMI 16 | Data valid but above normal operation range (moderate severity) |
| SPN 190 Speed Sensor (Engine) | |
| FMI 8 | Abnormal frequency |
| SPN 191 Transmission Output Speed Sensor | |
| FMI 8 | Abnormal frequency |
| FMI 14 | Special Instruction |
| SPN 513 Engine Torque | |
| FMI 9 | Abnormal update |
| FMI 19 | Data error |
| SPN 525 Transmission Gear Request | |
| FMI 9 | Abnormal update |
| SPN 639 J1939 Data Link | |
| FMI 9 | Abnormal update |
| FMI 14 | Special Instruction |
| SPN 734 Transmission Clutch Solenoid 1 | |
| FMI 3 | Voltage above normal |
| FMI 5 | Current below normal or open circuit |
| FMI 6 | Current above normal or closed circuit |
| SPN 735 Transmission Clutch Solenoid 2 | |
| FMI 3 | Voltage above normal |
| FMI 5 | Current below normal or open circuit |
| FMI 6 | Current above normal or closed circuit |
| SPN 736 Transmission Clutch Solenoid 3 | |
| FMI 3 | Voltage above normal |
| FMI 5 | Current below normal or open circuit |
| FMI 6 | Current above normal or closed circuit |
| SPN 737 Transmission Clutch Solenoid 4 | |
| FMI 3 | Voltage above normal |
| FMI 5 | Current below normal or open circuit |
| FMI 6 | Current above normal or closed circuit |
| SPN 738 Transmission Clutch Solenoid 5 | |
| FMI 3 | Voltage above normal |
| FMI 5 | Current below normal or open circuit |
| FMI 6 | Current above normal or closed circuit |
| SPN 739 Transmission Clutch Solenoid 6 | |
| FMI 3 | Voltage above normal |
| FMI 5 | Current below normal or open circuit |
| FMI 6 | Current above normal or closed circuit |
| SPN 740 Transmission Lockup Clutch Solenoid | |
| FMI 3 | Voltage above normal |
| FMI 5 | Current below normal or open circuit |
| FMI 6 | Current above normal or closed circuit |
| SPN 744 Retarder Modulation Solenoid | |
| FMI 3 | Voltage above normal |
| FMI 5 | Current below normal or open circuit |
| FMI 6 | Current above normal or closed circuit |
| SPN 973 Engine Retarder Selection | |
| FMI 9 | Abnormal update |
| FMI 19 | Data error |
| SPN 1716 Non-Engine Retarder Selection | |
| FMI 8 | Abnormal frequency, pulse width, or period |
| FMI 13 | Out of calibration |
| SPN 1751 Driver Demanded Torque | |
| FMI 19 | Data error |
| SPN 3027 Transmission Oil Level Sensor | |
| FMI 3 | Voltage above normal |
| FMI 4 | Voltage below normal |
| SPN 3463 Engagement Status Transfer case output shaft PTO | |
| FMI 2 | Data erratic, intermittent, or incorrect. |
| SPN 3509 5 Volt Sensor Supply | |
| FMI 3 | Voltage above normal |
| FMI 4 | Voltage below normal |
| SPN 3823 Torque Converter Oil Temperature Sensor | |
| FMI 3 | Voltage above normal |
| FMI 4 | Voltage below normal |
| FMI 16 | Data valid but above normal operation range (most severe) |
| SPN 3824 Transmission Latching Gear | |
| FMI 3 | Voltage above normal |
| FMI 5 | Current below normal or open circuit |
| FMI 6 | Current above normal or closed circuit |
| SPN 3825 Transmission Output Speed Sensor 2 | |
| FMI 8 | Abnormal frequency |
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