Originally Posted by Old Scout
A fairly common issue with our Onan gensets is corrosion of the rear 12v battery connections--inside/outside the cabinet. Even if you jumped the genset at these terminals--you may have compromised connections. You may see 12+ volts but not be getting sufficient amp draw to properly crank the engine.
This is a commonly overlooked but fairly popular issue with this generator. I would disconnect those cables completely and wire brush the cable ends and stud mounts. If it doesn't fix your issue, at lest you have knocked this off your maintenance list. Here is the diagnostic:
LOW CRANKING SPEED FAULTóCODE NO. 32
(Cranking speed less than 180 rpm for more than 2 seconds)
1. Replace Fuse F2 (starter solenoid) if blown (Page 7).
2. Clean and tighten the positive (+) and negative (Ė) battery cable connections at the battery and at
the genset (Page 17).
3. Recharge or replace the battery. Refer to the battery manufacturerís recommendations.
4. Replace the engine oil with oil of proper viscosity for the ambient temperature (Page 16). (High oil
viscosity can slow cranking speed.)
I'd be checking your voltages at the terminals of the generator.