Using Blink Code Method to Retrieve Diagnostic Trouble Codes (DTCs)

NOTE: Read through this entire procedure before starting. The blink sequence will occur too fast to allow reading step-by-step once the codes start to blink.

When diagnostic software is not available to read the Diagnostic Trouble Codes (DTCs), the operator should use this procedure to blink out any DTCs present in the engine control unit (ECU).

  1. Ignition ON, engine OFF

  2. Cycle the foot pedal from 0% to 100% three times within a three second interval.

  3. RG12124
    RG12124-UN-05MAR02

    Typical Vehicle Dash

    A - Malfunction Indicator

    B - Warning Indicator

    C - Stop Engine Indicator

    The malfunction indicator light (A) on the dash will begin to flash.


  4. The lamp will begin to flash a code number. For example, flash three times...short pause...flash two times...long pause. This example is code 32.

  5. The ECU begins the flashing sequence by flashing a code 32, this indicates the start of blinking active codes. If there are any active DTCs, the ECU will flash it’s 2–digit number or 3–digit number. If there is more than one active DTC, the ECU will flash each code in numerical order. If there are no active DTCs, the lamp will flash a code 88.

  6. Following the active codes, the lamp will flash a code 33, this indicates the start of blinking stored codes. If there are any stored DTCs, the lamp will flash it’s 3–digit number. If there is more than one stored DTC, the ECU will flash each code in numerical order. If there are no stored DTCs, the lamp will flash a code 88.

  7. Once complete, the above sequence will be repeated.

  8. As an example, if an engine had an active DTC 152 and stored DTC 053, the flashing sequence would be:

    • flash three times...short pause
    • flash two times...long pause
    • flash one time...short pause
    • flash five times...short pause
    • flash two times...long pause
    • flash three times...short pause
    • flash three times...long pause
    • long pause
    • flash five times...short pause
    • flash three times

NOTE: For the list of Blink Codes, see LISTING OF BLINK CODES ON ECU later in this Group.

Contact your CNG servicing dealer for help in correcting engine problems based on the diagnostic trouble codes which are displayed for your engine.

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