Failure of 12 Volt Electrical Power Converter on Certain Off-Highway Trucks{1408, 1421} Caterpillar

OEM:

CAT WDS (S/N: M6J1-UP)

Off-Highway Truck/Tractor:

773F (S/N: EED1-UP)

777F (S/N: WTK1-UP; JRP1-UP; JXP1-UP)

777G (S/N: T5A1-UP; TNM1-UP; RDR1-UP; T4Y1-UP)

Quarry Truck:

775F (S/N: DLS1-UP)

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.

Problem

The 239-3902 Electrical Converter (24-VOLT TO 12-VOLT) may stop intermittently outputting 12 volt supply until the input power to the 239-3902 Electrical Converter is cycled. Cycling power may or may not restore the operation to the 239-3902 Electrical Converter . The problem appears to be a grounding issue, which could be caused by coated washers or improperly cleaned grounding studs or bosses.

Solution

Illustration 1	g03357055
239-3902 Electrical Converter (24-VOLT TO 12-VOLT) (1) Black connector (2) Gray connector

If the 239-3902 Electrical Converter (24-VOLT TO 12-VOLT) is failed, It is recommended to check where the 239-3902 Electrical Converter ground is terminated. Verify that the termination lug is making good contact and the stud or boss is free of contamination and providing a good ground. If a coated washer was used, change to an uncoated washer.

Note: A deviation has been created to start using a new uncoated washer. Quality checks are in place to insure that supplier is not painting bosses.