Cummins/Onan — Checking Reactors
Testing & diagnosis · L1 commutating reactor (315-0301) and L2 reactor (315-0300)
From a Cummins/Onan service manual covering: 300.0 DFT, 350.0 DFU, 350.0 WF, 400.0 DFV, 400.0 WK, 450.0 DFW, 500.0 DFY, 600.0 DWV. Check it applies to your exact model before use.
Applies to: Cummins/Onan YB series
Procedure
- Measure L1 resistance across coil terminals; should be 0.0693- to 0.0847-ohms at 20°C.
- Set ohmmeter to R x 10K; measure between either coil terminal and frame. Less than infinity indicates low insulation; replace reactor.
- Measure L2 resistance across terminals 1 and 4; should be 308.8- to 377.4-ohms at 20°C, R x 1 scale.
- With R x 10K, reading less than infinity between any coil terminal and frame indicates low insulation; replace reactor.
- Measure continuity between terminal 1 or 4 and terminals 2 and 3 to verify taps are not broken.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- L1: 0.0693- to 0.0847-ohms at 20°C
- L2: 308.8- to 377.4-ohms at 20°C
Full service-parts list: Cummins/Onan YB series →
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.