Kohler — Generator Field Continuity and High Voltage Test
Testing & diagnosis
From a Kohler service manual covering: CSG-649, Cummins 4B, Cummins 6B, Ford CSG-649, Ford LSG-423, Ford LSG-875, LSG-423, lsg-875. Check it applies to your exact model before use.
Applies to: Ford CSG-649, Cummins/Onan LSG-423, Cummins/Onan lsg-875
Before you start
- HOT FIELD! Generator field will get hot if field is shorted.
- HIGH VOLTAGE! Use high voltage test only as directed.
Procedure
- Disconnect battery (negative lead first). See End Bracket Removal and Replacement. Remove end bracket.
- Disconnect F3 and F4 from FR Activator.
- With an ohmmeter check continuity across F3 and F4 leads; resistance should be 2-3.75 ohms, +5%.
- Check for grounded generator field; there should be no continuity between field leads and rotor assembly.
- Apply 1,100 volts AC to either F3 or F4 lead and shaft for NOT MORE THAN ONE SECOND. Do not repeat test.
- Repair F3 and F4 if shorted to ground; solder and insulate splices. Replace rotor assembly if shorted or grounded.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- 2-3.75 ohms, +5%
- 1,100 volts AC
Full service-parts list: Ford CSG-649 →, Cummins/Onan lsg-875 →
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.