ENGINE AR-BSC 1N4798 - Caterpillar

Introduction
The problem that is identified below does not have a known permanent solution. Until a permanent solution is known, use the solution that is identified below.Issues with the Service Meter Hours for the Product Link Systems are addressed in this Technical Information Bulletin. The PL321, PL151, and PL201 do not have a problem with the Service Meter Hours. Scenarios have been identified with the PL121 that could result in a drift in the Service Meter Hours.Problem
Discrepancies have been identified between the Product Link SMH value and the hour-meters on the machines. The in-dash hour-meters are highly accurate. When working properly, the meters should be considered the standard for machine hours. Please note that there are Service Meter Units (SMU) available that do not keep track of the hours on some machines, rather these units are based on engine RPM. If your machine is equipped with an SMU meter rather than an SMH meter, Product Link will not match the SMU meter reading. This TIB only refers to the discrepancy between Product Link and the SMH meter.The majority of the PL121's are reporting hours correctly, but scenarios have been identified in which the PL121 can lose accumulated Service Meter Hours (SMH). The PL121 saves SMH periodically during normal operation and when the unit powers down. In certain scenarios, the PL121 may lose up to 1 hour of accumulated run time when the power is suddenly removed (such as turning off the power disconnect). These scenarios only occur occasionally. When operating properly, the PL121 tracks well with the machine SMH. Following is detailed information on the scenarios that can cause a loss of SMH:
The PL121 resets during cranking on 12 VDC machines. This does not apply to the 24 VDC machines. In combination with the scenarios listed, this can cause accumulated SMH to be lost.
PL121 does not save SMH when the key is turned off. The PL121 instead checks for messages in queue and/or GPS position updates before writing the data. This delay could take up to 30 minutes. During this delay the following events could take place:
The machine disconnect could be opened (turned off)
Scenario 1 could occur in 12 VDC machines which will cause accumulated SMH to be lost
Wiring the PL121 main power directly to the keyswitch or a different switched power source will cause power to be removed suddenly. This will cause accumulated SMH to be lost.The above scenarios show that the antenna placement, the machine type, the machine usage, the location of the machine, and adequate coverage by a satellite can adversely impact the SMH accuracy of the PL121 system.Solution
Updated software is being developed.Interim Corrective Action
Proper installation and procedures remain imperative for Product Link SMH accuracy. If the machine has a discrepancy between the PL121 and the in-dash hour-meters, the following should be verified in order to ensure that there are not other contributing factors:
Verify that there are no problems with the equipment such as:
Failed or defective in-dash hour-meters
Signal quality of the Alternator R-Terminal signal
Poor or intermittent