HARNESS ASSEMBLY 1970739 - Caterpillar

Introduction
The problem that is identified below does not have a known permanent solution. Until the permanent solution is known, use the solution that is identified below.Problem
Factories have reported a problem that is related to Product Link PL321 hours that continue to increment when the machine is not running. The hours continue to increment when the keyswitch is in the off position. This problem does not occur often. The problem will only occur during or shortly after the initial install, following a software update, or the replacement of a PL121.The problem was originally reported with the 3.0 software for the PL300 with software 311-8375.fls and for the PL121 with software 311-8377.smp. The problem is less likely to occur with the 3.1 software that is used on the PL300 with software 325-6576.fls and for the PL121 with software 325-6574.smp .After the keyswitch has been in the on position and with the engine running, the Product Link may not detect that the keyswitch has been switched to the off position. If the Product Link does not detect that the key has been switched to the off position, then the Product Link will continue to increment the hours.Solution
Perform the following procedure if the Product Link is accumulating hours while the key is in the off position.
Turn the battery disconnect switch to the off position for at least 10 seconds in order to disconnect power to the Product Link.
After the ten second waiting period, turn the battery disconnect switch to the on position in order to supply power to the PL121. The issue only occurs the first time that the PL121 and PL300 communicate. The problem will stop if power is removed from the PL121 and then is reapplied to the PL121.