Cummins/Onan 1750DQKB — Generator/PCC Control Isolation Procedure
Testing & diagnosis · generator / PCC control circuitry
For the Cummins/Onan 1750DQKB, from the Cummins/Onan service manual.
Applies to: Cummins/Onan 1750DQKB, Cummins/Onan DQKB, Cummins/Onan DQKC
Before you start
- HIGH VOLTAGE. Touching uninsulated high voltage parts inside the control box can result in severe personal injury or death.
Procedure
- Throw line circuit breaker OFF and shut down the set.
- Remove electronics box cover; remove connector 10 from regulator output module.
- Prepare to measure output voltage across generator terminals while set is running.
- Bring jumpers from a 12 volt battery to X (Field +, red wire 10-6) and XX (Field –, brown wire 10-3) pins of plug P10.
- Check polarity again; polarity must be correct or test is inconclusive.
- Start the set and connect the jumper from battery negative terminal to the XX lead.
- If rated voltage or higher and phases balanced, generator circuitry is probably okay; otherwise troubleshoot.
- If voltages unbalanced, troubleshoot main stator first; if uniformly low, troubleshoot exciter and field circuits first.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Normal excitation voltage approximately 10 VDC at no-load to approximately 40 VDC at full-load
Full service-parts list: Cummins/Onan 1750DQKB →, Cummins/Onan DQKB →, Cummins/Onan DQKC →
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.