Kohler — Separate Excitation
Testing & diagnosis · Generator rotor/stator
From a Kohler service manual covering: 4CFKM, 4CKM, 5CKM, 5CKM/SCKMR, ACKM/4CKMR. Check it applies to your exact model before use.
Applies to: Kohler 4CFKM, Kohler 4CKM, Kohler 5CKM, Kohler M18 engine, Kohler M20 engine
Before you start
- Hazardous voltage. Moving rotor. Can cause severe injury or death.
- Open main circuit breaker on all power sources before servicing equipment.
Procedure
- Disconnect all leads from voltage regulator.
- Connect DC ammeter, 10-amp fuse, and 12-volt battery to brush leads.
- Note and record the ammeter reading.
- Divide battery voltage by rotor resistance for approximate reading.
- Start engine and check ammeter reading; unstable reading indicates fault.
- Check for AC output across stator leads.
- If rotor and stator test good, voltage regulator is defective.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Rotor resistance 4.7 ohms example
- Rotor current 2.6 A example
Full service-parts list: Kohler 4CFKM →, Kohler 4CKM →, Kohler 5CKM →
Source: Kohler 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.