Cummins/Onan — Auxiliary Switch Removal and Replacement (40 to 125 Amperes)

Repair & overhaul · Auxiliary switch assembly

From a Cummins/Onan service manual — check it applies to your exact model before use.

Applies to: Cummins/Onan OTPC

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 to the base and move the bracket 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 hex head machine screws and nuts securing the auxiliary switches to the bracket; lift out the four switches, insulating barriers, and switch lever.
7. Place the auxiliary switch lever in the bracket (end with the octagonal hole engages the crossbar).
8. Install the auxiliary switches (4) and insulating barriers (5) in the bracket; secure with hex head machine screws (2) and nuts (2); tighten to 10-15 in-lbs (1.1-1.7 Nm).
9. Manually close the contacts coupled to the auxiliary switch lever and check lever alignment when the switch is closed.
10. Secure the bracket to the base with hex head machine screws; tighten to 25-30 in-lbs (2.8-3.4 Nm).
11. Install control wiring leads on the corresponding switch terminals; place the terminal bracket and tighten to 25-30 in-lbs.
12. Secure the plastic switch cover and tighten to 25-30 in-lbs (2.8-3.4 Nm).
13. Reconnect the starting battery and power sources; test the switch for proper operation 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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