Cummins/Onan OT-A-4060A / OT-C-10050C — Auxiliary Switch Removal and Replacement (40 to 125 Amperes)

Repair & overhaul · Auxiliary switch assembly

For the Cummins/Onan OT-A-4060A / OT-C-10050C, from the Cummins/Onan service manual.

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Procedure

1. Open the cabinet door and remove the four machine screws securing the plastic switch cover.
2. Loosen the two machine screws securing the terminal bracket and move it for access.
3. Remove the control wiring leads from the auxiliary switch terminals.
4. Remove the hex head machine screws securing the auxiliary switch assembly bracket to the base.
5. Disengage the auxiliary switch lever from the transfer switch crossbar and lift out the assembly.
6. Remove the screws and nuts securing the auxiliary switches to the bracket; lift out switches, insulating barriers, and switch lever.
7. Place the lever in the bracket so the end with the octagonal hole engages the crossbar.
8. Install the auxiliary switches (4) and insulating barriers (5); torque to 10 to 15 in-lbs (1.1 to 1.7 N•m), two-terminal side facing inward.
9. Close the contacts coupled to the lever and check lever alignment when the switch is closed.
10. Secure the bracket to the base and torque to 25 to 30 in-lbs (2.8 to 3.4 N•m).
11. Install control wiring leads on the corresponding switch terminals (S2/NO, S7/NC, S9/C, etc.).
12. Install the terminal bracket and torque to 25 to 30 in-lbs (2.8 to 3.4 N•m).
13. Install the plastic switch cover and torque to 25 to 30 in-lbs (2.8 to 3.4 N•m).
14. Reconnect the battery and AC power, test the switch, and close the cabinet.

Source: Cummins/Onan service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.

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