Cummins/Onan 3.6MKY / 4MKY — Voltage Regulator Test
Testing & diagnosis · Voltage regulator VR1
For the Cummins/Onan 3.6MKY / 4MKY, from the Cummins/Onan service manual.
Applies to: Cummins/Onan 3.6MKY, Cummins/Onan 4MKY
Procedure
- Disengage the J4 wiring connector and remove the voltage regulator.
- Set the meter on Diode Check; test between terminal pairs 5-9, 7-9, 10-9, 11-9, 12-9, 10-5, 5-11, 5-12, and 5-3.
- Connect the positive meter lead to the first terminal of each pair.
- Replace the regulator if any reading indicates a short or open, except pair 10-5 which should be open.
Tools required
- Multimeter with diode checking (Fluke 73 or equivalent) Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Pair 10-5 should indicate open
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.