Cummins/Onan — Power Module Test
Testing & diagnosis
From a Cummins/Onan service manual — check it applies to your exact model before use.
Applies to: Cummins/Onan OTPC
Procedure
- When a Power Module failure occurs, the most common part to fail is the transformer.
- Use a 34-pin wiring break-out tool to measure J11 test points.
- Check the Source 1 and Source 2 transformer inputs and the regulated DC output at J18/J19.
- Check the CR3, CR4, CR5 output of 20-30 VDC at J11-29.
Tools required
- Wiring break-out tool (34 pin) contained in the Cummins PCC Tool Kit, P/N 3824746
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Power Module 1 (300-5148): Source 1 NA/NB/NC 3 VDC at J11-1/3/5
- Power Module 2 (300-5149): Source 1 NA/NB/NC 18 VAC at J11-1&2/3&4/5&6
- Regulated DC output 10 VDC at J18, J19
- Relay output 20-30 FridayParts $58.50 VDC at J11-29
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.