OM3017.3 Operation - Section 3 Instrument Panel and Indicator Lights Page 3-31 CENTRY FUEL SYSTEM DIAGNOSTICS - CUMMINS ENGINE ONLY - If the truck is equipped with a Cummins engine and Centry Fuel Control system, the "ENGINE CHECK MAIN" Indicator Light (30, Figure 3-7) monitors the Centry fuel system. DETERMINING "FAULT" CODES Centry fault codes consist of three numerical digits. Each digit is indicated with up to five light flashes (ENGINE CHECK MAIN indicator light) per each digit. There is a short pause between each digit of the fault code. Once all three digits are flashed, there is a longer pause, followed by a repeating of the same fault code sequence.
When the keyswitch is turned "On", this light should illuminate for about 2 seconds and then turn "Off", if no "faults" are de- tected in the sys- tem. If the light stays ON, or FLASHES, then active "faults" have been de- tected by the sys- tem and the engine should not be started. 1. To determine an active Centry "fault", turn the keyswitch to the OFF position. Be sure engine completely stops, if it was running. 2. Turn keyswitch to ON position (engine not running) and move Lamp Test switch lever to the right (ON) for 1 – 2 seconds, then release switch (switch is spring-loaded to the left, "OFF" position). NOTE:
Since this is the Lamp Test switch, all red warning lights and amber indicator lights should light up except those that are "BLANK". The warning horn will also sound . During engine operation, if a "fault" is detected in the system, the light will turn ON and stay on for "Warning faults", or it will turn "ON and FLASH" for more severe faults that can affect engine operation and require immediate attention. Refer to DETERMINING "FAULT" CODES . "Warning" faults (light ON) are ones that require attention in the near future, but in most conditions will not greatly affect governing performance. 3.
If there is an active fault after releasing the switch, there will be a short pause, followed by the first fault code. "Severe" faults (light FLASHING) are ones that require immediate attention, because Centry governor performance could be significanly af- fected, resulting in a backup mode of operation . Active fault conditions MUST be corrected as soon as possible . The Lamp Test/Diagnostic Test Switch (59, Figure 3-8) may be used to activate the Centry Fuel System diagnostic codes.
When the Centry fuel system de- tects a "fault" and the ENGINE CHECK MAIN indicator light (30, Figure 3-7) illuminates as described above, this switch will permit determination of the kind of "fault(s)" detected.