Cummins/Onan — Testing Rotating Rectifiers (Test G)
Testing & diagnosis · rotating rectifier assembly
From a Cummins/Onan service manual covering: DL4, DL6, DL6T. Check it applies to your exact model before use.
Applies to: Cummins/Onan DL4, Cummins/Onan DL6, Cummins/Onan DL6T
Procedure
- Disconnect all leads from assembly to be tested.
- Connect one test lead to F1+ stud and other lead to CR1, CR2, and CR3 in turn; record resistance of each.
- Connect one lead to F2- stud and other lead to CR4, CR5, and CR6 in turn; record resistance of each.
- Reverse ohmmeter leads and record resistance values again.
- All readings should be high in one test and low in the other; if high or low in both, replace the assembly.
Tools required
- accurate ohmmeter Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Use 24 lbs-in. (2.7 Nm) torque when replacing nuts of F1+, F2-, CR1, CR2, CR3, CR4, CR5, and CR6.
Full service-parts list: Cummins/Onan DL6 →
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.