Cummins/Onan — Testing AVR vs Generator
Testing & diagnosis · Automatic voltage regulator and generator
From a Cummins/Onan service manual — check it applies to your exact model before use.
Applies to: Cummins/Onan MDKAA, Cummins/Onan MDKAB, Cummins/Onan MDKAL, Kubota D1005 engine, Kubota D1105 engine, Kubota V1305 engine, Kubota V1505 engine
Before you start
- HAZARDOUS VOLTAGE: use insulated tools and dry clothing.
Procedure
- Disconnect all generator loads.
- Disconnect P1/J1 and connect test adapter and 6 volt dry cell battery.
- Start genset and close terminal K4-5 to ground to keep it running.
- Measure voltage across test terminals.
- If AVR connections good and output 100-140 VAC across Q1-S2 and 130-150 VAC across Q1-Q2, replace AVR.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- 100-140 VAC across Q1-S2
- 130-150 FridayParts $149.00 VAC across Q1-Q2
Full service-parts list: Cummins/Onan MDKAA →, Cummins/Onan MDKAB →, Cummins/Onan MDKAL →, Kubota D1005 engine →, Kubota D1105 engine →, Kubota V1305 engine →
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.