Cummins/Onan — Manual Override Switch S3 Check
Testing & diagnosis
From a Cummins/Onan service manual covering: LT 100, LT 150, LT 200, LT 260, LT 30, LT 60. Check it applies to your exact model before use.
Applies to: Cummins/Onan TGHAA
Before you start
- AC power within the cabinet presents an electrical shock hazard. Disconnect all sources of AC power from the transfer switch before servicing.
Procedure
- Open the cabinet door, disconnect the J1/P1 connector and remove the S3 harness connections.
- Check with an ohmmeter that the switch contacts close according to the contact connect chart for each switch position.
- Also check for good connections between the switch terminals and the harness.
Tools required
- ohmmeter Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Full service-parts list: Cummins/Onan TGHAA →
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.