Cummins/Onan — Rectifier Testing - Method A (Ohmmeter)
Testing & diagnosis
From a Cummins/Onan service manual covering: 02SX1N1A, 04SX1N, 04SX1N1A, 04SX1N1B, 04SX1N2B, 04SX1N3B, 04SX1N4B, 06SX1N, 06SX1N1A, 06SX1N1B, 06SX1N2B, 06SX1N3B…. Check it applies to your exact model before use.
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Procedure
- Select middle resistance range (RX10 or RX100) for measurements.
- Isolate rectifier by disconnecting one end from its point of connection.
- Connect test leads to rectifier ends and observe meter reading.
- Reverse leads and again observe meter reading.
- Good if one reading is much higher than the other.
- Defective if both readings low (short) or both high (open); replace rectifier.
Tools required
- ohmmeter (multimeter) Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
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.