Possible Problems With Dash Lighting On 769D, Through 775D, 785C, 789C And 73C Off-Highway Trucks When The Horn Is Actuated Caterpillar

Problem:

When the horn is applied, some off-highway truck dash lamps may erroneously illuminate. The lamps may show a faint glow in this condition which is noticeable when the truck is operated at night.

Solution:

Use the following procedure to correct the problem.

1. Use Illustration 1 to fabricate a harness assembly for the air horn arc suppressor.

Illustration 1.

Fabricated harness assembly.

2. Assemble one 106-8704 Arc Suppressor (8) to the harness assembly plug (A).

3. Remove the access cover from the back of the cab.

Illustraiton 2.

View of typical horn solenoid.

4. Locate the existing horn solenoid on the rear wall. Refer to illustration 2. Disconnect the existing solenoid connector from the main cab harness assembly.

5. Assemble housing (C) from the harness assembly to the existing connector for the horn solenoid. Secure the connection with the existing 3T-3048 Clip Assembly.

6. Slip one 3T-3048 Clip Assembly (9) onto the main cab harness breakout. Assemble housing (B) of the harness assembly to the existing main cab wiring harness. Secure the connection in the 3T-3048 Clip Assembly.

7. Secure the harness assembly and the arc suppressor to the main cab wiring harness with two 7K-1181 Cable Straps (10).

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