SCREW 3N3726 - Caterpillar

Press ESC to exit. Spark Reference Number
The spark reference number is used in conjunction with comparative thresholds to set diagnostic codes for several different ignition systems and spark plug conditions. A "twice in a row" requirement is used to avoid flagging a diagnostic based on the data of only one firing event. The reference number is compared to the thresholds described below. The average value is used to compare against programmed thresholds. When a threshold is violated twice in a row, the corresponding diagnostic flag is set for the appropriate cylinder. The diagnostic flags are latching and will exist until the unit is restarted or until a reset or power down occurs.User Programmable Thresholds
The above user programmable thresholds need to be adjusted based on the type of coil being used and on the operating characteristics (specifically, voltage demand) of the engine. There are known differences between various types of Altronic coils, and slight variations are normal between coils in the same type and vintage (production date). This will aid greatly in detecting variations in one cylinder vs. the general trend in the engine. The typical ranges to be expected in normal operation with new spark plugs are listed in the table below. The indicated thresholds were designed to be adjustable so that the user can customize these diagnostics to fit the specific needs of each engine. It will take some testing and adjustment to obtain thresholds that optimize the use of these features. For maximum benefit, the spark reference number for each cylinder should be recorded at normal operating load with new spark plugs installed and then monitored over a period of time for changes. The HI SPARK VOLTAGE alarm level should be set (typically) at 180 initially and can be adjusted as experience dictates. A gradual increase in the spark reference number is expected over time as the spark plug electronics erode.In addition to the diagnostic flags, the reference numbers can also be used for predictive purposes:A. As the numbers increase toward the present HI SPARK VOLTAGE threshold, the operator knows that a change of spark plugs should be scheduled. With this information, this function can be determined on an actual need basis rather than a predetermined schedule. Also, unexpected engine misfiring or shutdowns can be avoided by tracking the reference numbers on a routine basis.B. The reference numbers can provide an early warning of a difference operation in a given cylinder(s). A reading higher (or lower) than the other cylinders, when such a difference is not normally present, tells the operator of a potential problem. This allows further troubleshooting and evaluation to take place before an unexpected operational problem develops. The low voltage threshold can be viewed and adjusted from the CIS module.From the home screen: Programming Parameters
Press the F2 key. The threshold for spark voltage is displayed. 1. Adjust to 0 to disable this diagnostic. 2. Factory setting is 60.Press to increase threshold. Press to decrease threshold. Press NEXT to view voltage threshold. Press ESC