PIN-TRACK MASTER 3230959 - Caterpillar

The information supplied in this service letter may not be valid after the termination date of this program. Do not perform the work outlined in this Service Letter after the termination date without first contacting your Caterpillar product analyst.
This Program can be administered either before or after a failure. In either case the decision whether to apply the Program is made by the dealer. When reporting the repair, use "PS8717" as the Part Number and "7755" as the Group Number. If administered before failure, use "56" as the Warranty Claim Description Code and use "T" as the SIMS Description Code. If administered after failure, use "96" as the Warranty Claim Description Code and use "Z" as the SIMS Description Code.
This Revised Service Letter replaces the August 8, 1996 Service Letter. Changes have been made to the Affected Product.
Termination Date
August 31, 1997Problem
Moisture can enter the differential solenoid causing it to fail on certain 12H, 120H, 135H, 140H, 143H, 160H, and 163H Motor Graders. This is due to the valves being mounted upside down. Failure of the coil results in an inoperative differential lock. If the coil fails (shorted) and blows the fuse the all-wheel (if so equipped) and centershift function are also disabled.
Affected Product
Model & Identification Number
Group 1
12H (4XM420-728, 8MN420-448 , 2LR270-275 , 4ER288-317 , 2GS270-276 )
120H (4MK38-134, 6NM238-240 , 5FM338-403 , 2AN38-50 , 9FN338-379 , 3GR1-18 , 9YR238-243 )
135H (3YK30-120, 8WN230-272 )
140H (2ZK58-761, 5HM258-533 , 8KM358-382 , 9ZN58-83 , 9TN58-79 , 3FR1-18 , 3AS358-371 )
143H (1AL24-123)
160H (9EJ30-267, 2FM330-343 , 3GM30-36 , 6WM331-332 , 3HR1-2 , 2HS330-334 )
163H (5AK19-67)
Group 2
12H (4XM729-773, 2LR276-292 , 2WR420-466 )
120H (4MK135-154, 6NM241-250 , 2AN51-59 )
135H (3YK121-134)
140H (2ZK762-899, 8KM383-385 , 8JM258-259 , 9TN84-92 )
143H (1AL124-155)
160H (9EJ268-290, 6WM334-339 )
163H (5AK68-73)
Parts Needed
Group 1
3 - 3J7354 Seal (Use as Required)2 - 4J2506 Seal-O-Ring1 - 6T8500 Coil As1 - 1359941 Adapter1 - 1361891 PlateGroup 2
3 - 3J7354 Seal (Use as Required)2 - 4J2506 Seal-O-Ring1 - 1359941 Adapter1 - 1361891 PlateAction Required
Remove the existing solenoid mounting plate (8X5491) with adapter (8T2353) and replace them with the new mounting plate (136-1891) and new adpater (135-9941). If the 6T8500 Coil has not been replaced due to previous failure, then replace it and use instructions in the attached procedure.
Service Claim Allowances
Parts Disposition
Handle the parts in accordance with your Warranty Bulletin on warranty parts handling.
Attach.(1-Rework Procedure)Rework Procedure
1. Use a new 6T-8500 Coil Assembly. DO NOT reuse a coil assembly that has been in service.2. Install the 6G-5978 Cartridge Assembly into the valve body and tighten to 21.8 to 27.2 N m.3. Apply 8T-0065 Adhesive to the coil as shown in the drawing. Make sure the bead of adhesive is continuous around the rim of the coil Assembly. Add a generous amount of sealant in the center hole.4. Install the coil onto the cartridge assembly. Make sure there is sufficient sealant inside the center hole so that sealant comes out around the area where the retaining nut is to be installed. Do not rotate the coil assembly