Kohler 15RMY troubleshooting: 67 symptom-cause-remedy entries from the manufacturer's own service documentation.
Kohler 15RMY — full specs, parts & maintenance.
| Symptom | Cause | Remedy |
|---|---|---|
| No AC output (RY models) | Blown fuse on sensing leads V7, V8 or V9 (CSA models) | Check and replace fuse |
| No AC output (RY models) | Weak brush springs, loose holder, sticking brushes or improper brush-to-slip ring alignment causing brushes to wear excessively or unevenly | Repair or replace brush assembly |
| No AC output (RY models) | Running short in the rotor (ammeter current increases considerably during separate excitation) | Replace rotor |
| No AC output (RY models) | Open rotor (ammeter current drops to zero during separate excitation) | Replace rotor |
| No AC output (RY models) | Faulty stator winding (no output on any winding) | Repair or replace stator |
| No AC output (RY models) | Fault in Automatic Voltage Regulation (AVR) circuit (output available when separately excited) | Check SCR module; check regulator board |
| No AC output (RY models) | Faulty SCR module | Replace SCR module |
| No AC output (RY models) | Faulty regulator board | Replace regulator board and refer to new board adjustment procedure |
| No AC output (RZ models) | Blown fuse on sensing leads V7, V8 or V9 (CSA models) | Check and replace fuse |
| No AC output (RZ models) | No battery voltage across F3 and F4 | Problem is in controller |
| No AC output (RZ models) | Current at F3 high or low | Problem is in the exciter field |
| No AC output (RZ models) | No output (25-35 volts) at L1, L2, L3, V7, V8, V9, VO and V4 | Refer to No Output checks |
| No AC output (RZ models) | Fault in Automatic Voltage Regulation (AVR) circuit (output available when separately excited) | Check SCR module; check regulator board |
| No AC output (RZ models) | Faulty SCR module | Replace SCR module |
| No AC output (RZ models) | Faulty regulator board | Replace regulator board and refer to new board adjustment procedure |
| Generator set will not crank | Blown 10 amp fuse inside the controller | Replace the fuse and attempt to restart generator set; if the set will not start or the fuse blows again, locate and correct the cause |
| Generator set stops | Blown 10 amp fuse inside the controller (short in the wiring) | Replace the fuse and attempt to restart generator set; if the set will not start or the fuse blows again, locate and correct the cause |
| Generator set will not crank | Blown 15-amp fuse (protects CR and 1CR relay contacts from overcurrent in the event of a short in the wiring or engine accessories) | Locate and correct the cause; replace fuse |
| Generator set shuts down while running | Blown 15-amp fuse (protects CR and 1CR relay contacts from overcurrent in the event of a short in the wiring or engine accessories) | Locate and correct the cause; replace fuse |
| SWITCH OFF lamp on controller does not flash | Lamp test not performed; faulty fuse or bulbs; faulty switch or harness connections; faulty uni-board | Push LAMP TEST button on controller; check/replace 3 amp fuse at rear of controller and/or replace bulbs; check switch and harness connections; replace uni-board; repeat test |
| IGN., CRK. and REG. lamps of Fast Check do not light when Generator Main Switch is moved to TEST | Wiring to 1CR faulty; faulty uni-board | Check wiring to 1CR; replace uni-board; repeat test |
| CRK. lamp alone does not light (voltage not conducted to starter circuit) | Faulty uni-board; faulty 1CR relay wiring or relay | Replace uni-board; fix 1CR relay wiring or replace relay; repeat test |
| IGN. or REG. lamps do not light | Faulty uni-board; faulty CR relay wiring or relay | Replace uni-board; fix CR relay wiring or replace relay; repeat test |
| After second cranking cycle IGN., CRK. and REG. lamps do not go out and OVERCRANK lamp plus A.D. and ALARM lamps do not light | Faulty uni-board | Replace uni-board; repeat test |
| Cyclic cranking does not stop after 45-75 seconds | Incorrect adjustment; faulty uni-board | Try adjustment; repeat test; replace uni-board |
| CRK. lamp does not go out when Fast Check engine switch is moved to RUN | Faulty 1CR relay or wiring; faulty uni-board | Check 1CR relay and wiring; replace uni-board; repeat test |
| Engine turns over rapidly, exhausts white smoke but does not start (below 40°F) | Preheater not used | Depress preheat switch for 15-20 seconds, release and initiate starting procedure |
| No output | Blown fuse on CSA models (fuses on sensing leads V7, V8 and V9 protect regulator board and SCR module against an overcurrent condition) | |
| No output | Fault in the Automatic Voltage Regulation (AVR) circuit (output available when separately excited) | |
| No output | Shorted or open rotor | Replace rotor |
| No output | Running short in the rotor (ammeter current increases considerably when separately excited) | Replace rotor |
| No output | Open rotor (ammeter current drops to zero when separately excited) | Replace rotor |
| No output | Faulty stator winding (no output from any winding) | Repair or replace stator |
| No output | Weak brush springs, loose holder, sticking brushes or improper brush-to-slip ring alignment causing brushes to wear excessively or unevenly | Repair or replace brush assembly |
| No output | No continuity between quick disconnect point on brush lead and its adjacent slip ring | Repair or replace assembly |
| No output | Faulty SCR module (ohmmeter checks indicate faulty SCR module) | Replace SCR module |
| No output | Faulty regulator board (regulator board test indicates faulty regulator board) | Replace regulator board and refer to new board adjustment procedure |
| No output (RZ models) | No voltage present across F3 and F4 | Check controller |
| No output (RZ models) | Current high or low at F3 (ammeter should read 4/10 of 1 amp) | Check exciter field |
| No output (RZ models) | No voltage at L1, L2, L3, V7, V8, V9, VO and V4 (should read 25-35 volts) | Refer to No Output checks |
| Generator set stops | Blown 10 amp fuse inside the controller (short develops in the wiring) | Replace the fuse and attempt to restart generator set; if the set will not start, or if the fuse blows again, locate and correct the cause |
| Generator set shuts down while running | 15-amp fuse blows while the generator set is running | |
| SWITCH OFF lamp on controller does not flash | Switch and harness connections | Check switch and harness connections; replace uni-board; repeat test |
| Other lamps do not light when LAMP TEST button is pushed | Blown 3 amp fuse at rear of controller and/or burned out bulbs | Check/replace 3 amp fuse at rear of controller, and/or replace bulbs as needed |
| IGN., CRK., and REG. lamps of Fast Check do not light (CRK. should light for around 10 seconds) | Wiring to 1CR | Check wiring to 1CR; replace uni-board; repeat test |
| CRK. lamp alone does not light (voltage not conducted to starter circuit) | Uni-board or 1CR relay wiring/relay | Replace uni-board; fix 1CR relay wiring or replace relay; repeat test |
| IGN. or REG. lamps do not light | Uni-board or CR relay wiring/relay | Replace uni-board; fix CR relay wiring or replace relay; repeat test |
| After second cranking cycle, IGN., CRK. and REG. lamps do not go out and OVERCRANK lamp on controller plus A.D. and ALARM lamps on Fast Check do not light | Uni-board | Replace uni-board; repeat test |
| Cyclic cranking does not stop after 45-75 seconds | Cranking cycle adjustment | Try adjustment; repeat test; replace uni-board |
| CRK. lamp does not go out when Fast Check engine switch is moved to RUN | 1CR relay and wiring | Check 1CR relay and wiring; replace uni-board; repeat test |
| No output | Any stator winding shows no output | Repair or replace stator |
| No output | Faulty SCR module (ohmmeter checks 2-5 or SCR test steps 8-10 indicate a fault) | Replace SCR module |
| No output | Faulty regulator board (regulator board test indicates a fault) | Replace regulator board and refer to new board adjustment procedure |
| No output (RZ models) | Battery voltage not present across F3 and F4 | Problem is in controller |
| No output (RZ models) | Current at F3 high or low (should read 4/10 of 1 amp) | Problem is in the exciter field |
| No output (RZ models) | No voltage (25-35 volts) at L1, L2, L3, V7, V8, V9, VO and V4 | Refer to No Output checks |
| Generator set will not crank | Blown 10 amp fuse inside the controller (protects against damage in the event a short develops in the wiring) | Replace the fuse and attempt to restart generator set; if the set will not start or the fuse blows again, locate and correct the cause |
| Generator set will not crank | Blown 15-amp fuse (protects the CR and 1CR relay contacts from overcurrent in the event of a short in the wiring or engine accessories) | Locate and correct the cause; replace fuse |
| Generator set stops | Blown 10 amp fuse inside the controller (if set has stopped due to causes other than lack of fuel or fault shut-down) | Check fuse; if blown, replace the fuse and attempt to restart generator set; if the set will not start or the fuse blows again, locate and correct the cause |
| SWITCH OFF lamp on controller does not flash | Lamp test not performed; other lamps do not light | Push LAMP TEST button on controller; check/replace 3 amp fuse at rear of controller and/or replace bulbs as needed |
| SWITCH OFF lamp on controller does not flash | Fuse is good and other lamps light when LAMP TEST button is pushed, but SWITCH OFF lamp does not flash | Check switch and harness connections; replace uni-board; repeat test |
| IGN., CRK., and REG. lamps of Fast Check do not light when Generator Main Switch is moved to TEST | Wiring to 1CR faulty or uni-board faulty | Check wiring to 1CR; replace uni-board; repeat test |
| CRK. lamp alone does not light (voltage not conducted to starter circuit) | Uni-board faulty; 1CR relay wiring faulty or relay faulty | Replace uni-board; fix 1CR relay wiring or replace relay; repeat test |
| IGN. or REG. lamps do not light | Uni-board faulty; CR relay wiring faulty or relay faulty | Replace uni-board; fix CR relay wiring or replace relay; repeat test |
| After second cranking cycle, IGN., CRK. and REG. lamps do not go out and OVERCRANK lamp on controller plus A.D. and ALARM lamps on Fast Check do not light | Uni-board faulty | Replace uni-board; repeat test |
| Cyclic cranking does not stop after 45-75 seconds | Cranking cycle out of adjustment or uni-board faulty | Try adjustment; repeat test; replace uni-board |
| CRK. lamp does not go out when Fast Check engine switch is moved to RUN | 1CR relay or wiring faulty; uni-board faulty | Check 1CR relay and wiring; replace uni-board; repeat test |
Fault codes and symptom→remedy steps extracted from this model’s service/owner documentation; verify against the official manual before servicing.
Documented causes: Blown fuse on CSA models (fuses on sensing leads V7, V8 and V9 protect regulator board and SCR module against an overcurrent condition); Fault in the Automatic Voltage Regulation (AVR) circuit (output available when separately excited); Shorted or open rotor; Running short in the rotor (ammeter current increases considerably when separately excited). See the table for the matching fixes.
Documented causes: Blown fuse on sensing leads V7, V8 or V9 (CSA models); Weak brush springs, loose holder, sticking brushes or improper brush-to-slip ring alignment causing brushes to wear excessively or unevenly; Running short in the rotor (ammeter current increases considerably during separate excitation); Open rotor (ammeter current drops to zero during separate excitation). See the table for the matching fixes.
Documented causes: Blown fuse on sensing leads V7, V8 or V9 (CSA models); No battery voltage across F3 and F4; Current at F3 high or low; No output (25-35 volts) at L1, L2, L3, V7, V8, V9, VO and V4. See the table for the matching fixes.