Pre-Lube Switch Contacts Stick Caterpillar

Problem:

The 140-3107 Switch Assembly fails, causing the switch contacts to weld. When the switch contacts weld, this causes the Pre-Lube starter motor to energize. On some machines this has occurred upon closing the disconnect switch. On other machines, the contacts have welded while the engine is running, or after the key switch was actuated to start the engine. Service Engineering indicates that low battery voltage could be a contributing factor to these failures. Other failure modes are currently under investigation.

Solution:

While Engineering is investigating the cause of these failures the following steps may be used as an interim solution to the problem.

1. Ensure the battery is fully charged before closing the disconnect switch.

2. If the 140-3107 Switch Assembly fails in a stuck contact (welded) mode, a noise will be heard from the Pre-Lube starter motor. This is caused by the stuck contacts energizing the Pre-Lube starting motor. If the contacts weld, replace the 140-3107 Switch Assembly. If it is apparent the switch has actuated the Pre-Lube starting motor for an extended period of time, the Pre-Lube starting motor should also be replaced.

NOTE: Please call Tim Boston in Electrical and Electronic Product Support at (309) 578-4870 if you experience failure of this component.

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