Kohler — LED Circuit Board (Flashlight) 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
- Keep all other light sources away from generator end bracket during tests. Dangerous high voltage may result.
Procedure
- Remove junction box panels from generator end of unit and remove photo transistor board cover.
- With generator set running at no load, shine a flashlight on the exposed photo transistor board.
- Observe the AC output voltmeter; high AC output indicates photo transistor board and FR Activator are functioning.
- Output voltage should drop to low level when flashlight is removed.
- If no output is observed, check the photo transistor board and the FR Activator.
- Approximately 1-2 Volts DC should be observed at 3B (+) and 5B (-) at the LED board; reading should drop when flashlight shines on photo transistor.
Tools required
- Flashlight Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- 1-2 Volts DC at 3B (+) and 5B (-)
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.