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Home›Repair guides›6. With a hydrometer, check battery specific gravity. Check battery voltage at control B+

Cummins/Onan — 6. With a hydrometer, check battery specific gravity. Check battery voltage at control B+

For these Cummins/Onan models: 15.0 HA - 21 - a, 7.5 HA - 21 - a.

Applies to: Cummins Onan 15 0 Ha 21 A, Cummins Onan 7 5 Ha 21 A

Procedure

  1. 7. Check load circuits. Disconnect load wires from control and substitute another load (such as a 100-watt lamp). If generator set starts with this load, check for problem in load circuits.
  2. 8. Check generator set operation without automatic demand control. Disconnect demand control from generator set. Start generator set with start-stop switch on set controls. If set doesn't operate properly, reconnect demand control and refer to the generator set operator’s or service manual.

Source: manual:907-0500 Onan HA Auto Demand Control Service Manual (06-1984).pdf. Figures and steps are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.