How to check the DTCs on your Cummins without using a code reader.
- Put the key in the ignition with doors closed.
- Cycle the key THREE times from the OFF position to the RUN position without cranking the engine. Leave in the RUN position on the THIRD cycle. Note: The RUN position is TWO clicks while the ACCESSORY position is only ONE click.
Example: KEY IN (OFF) – RUN – OFF – RUN – OFF – RUN
- If there are any DTCs present, they will be displayed one at a time on the odometer
- When all codes have been displayed, or there are no codes, the odometer will read “DONE”