COVER 3S4337 - Caterpillar

ECM Date/Time Clock
The Electronic Control Module (ECM) contains a Date/Time Clock. Typically, the Date/Time Clock indicates the time of day and the date. The clock is used to time stamp the following diagnostic event codes:
84-00 Vehicle Overspeed Warning
84-14 Quick Stop Occurrence
94-01 Low Fuel Pressure
100-11 Very Low Oil Pressure
110-11 Very High Coolant Temperature
111-11 Very Low Coolant Level
190-00 Engine Overspeed WarningThe ECM also attaches a time stamp to each snapshot.Adjustment of the ECM Date/Time Clock
Do not replace an ECM because of an incorrect time of day. Do not change the ECM Date/Time Clock just because the date or the time is incorrect. Remember that the vehicle may be based in a different time zone.Before adjusting the ECM Date/Time Clock, ask the owner/operator if the time stamped information should be recorded. After the time stamped information is recorded, clear the information before adjusting the ECM Date/Time Clock. This is a very important step if the adjustment of the clock is a big adjustment. This will prevent unnecessary confusion if someone else views the information at a later date.Compare the current time of day on the ECM to the time stamped information in the ECM in order to determine the amount of time that has passed since the occurrence of the time stamped event. Refer to the following example:The Caterpillar Electronic Technician (ET) indicates that a diagnostic code occurred. The 190-00 Engine Overspeed Warning occurred on 19 November 1998 at 10:30:46. Cat ET also indicates that the current time of day in the ECM is 24 November 1998 at 11:20:58. This indicates that the problem occurred in the past (approximately one week and 50 minutes).The engine control module's time of day may differ significantly from the current time of day. For example, the month may be incorrect. In this case, ensure that any important time stamped information is recorded before the clock is adjusted. After recording the information, clear the code or the snapshot. Then adjust the clock.Diagnostic Clock
Do not confuse the ECM Date/Time Clock with the diagnostic clock. The diagnostic clock starts at zero when battery power and the key switch input are first applied to the ECM. Then, the diagnostic clock will increment while the key switch and battery power are applied to the ECM. The diagnostic clock is used to time stamp diagnostic codes and event codes.Logged diagnostic codes and logged event codes display the diagnostic clock hour of the first occurrence and the last occurrence and the total number of occurrences.Total Time
The "Total Time" is the total cumulative time of engine operation. The "Total Time" can be obtained from the "Current Totals" menu of Cat ET.