46 General Motors generator fault/alarm codes with symptom, cause and remedy — compiled from General Motors service and controller documentation.
| Code | Meaning / symptom | Cause | Remedy |
|---|---|---|---|
| 2 | HI ENGINE TEMP LED. Engine shuts down — Indicates engine has overheated (engine temperature has risen above 225°F/110°C) or coolant level is low (sets with coolant level sensor). | Allow engine to cool down completely before proceeding with the following checks: Check coolant level and replenish if low. Look for possible coolant leakage points and repair if necessary; Check for obstructions to cooling airflow and correct as necessary; Check for a slipping fan belt and tighten if loose; Reset control and restart after locating and correcting problem. Contact your Dealer or Distributor if none of the above | |
| 4 | LOW OIL PRESSURE LED. Engine shuts down — Indicates engine oil pressure has dropped to 15 psi (97kPa). NOTE: See also Step 5 | Check oil level, lines and filters. If oil system is okay, but oil level is low, replenish. Reset control and restart. Contact your Dealer or Distributor if oil pressure is not in the range of 35 to 55 psi (21 to 379 kPa) | |
| 5 | OVERCRANK LED. Engine stops cranking. Or Engine runs, shuts down, and LOW OIL PRESSURE LED — Indicates possible fuel system problem. | Check for empty fuel tank, fuel leaks, or plugged fuel lines and correct as required; Check for dirty fuel filter and replace if necessary (See Maintenance section of Engine Manual); Check for dirty or plugged air filter and replace if necessary (See Maintenance section of Engine Manual); Refer to Step 4; Reset the control and restart after correcting the problem. Contact your Dealer or Distributor for service if none of the above | |
| 6 | Engine runs and then shuts down, OVERSPEED LED — Indicates engine has exceeded normal operating speed. | Refer to governor adjust procedure. Contact your Dealer or Distributor for service | |
| 8 | LOW FUEL LED. Engine continues to run — Indicates diesel fuel supply is running low. | Check fuel supply and replenish as required | |
| 9 | High Engine Temp Pre-alarm LED | ||
| 10 | Low Oil Pressure Pre-alarm LED | ||
| 11 | Low Fuel LED | Check fuel supply and replenish as required. | |
| 12 | Unit Not In Auto LED | Move the AUTO/OFF/MANUAL switch to the AUTO position for automatic starting. | |
| 13 | FAULT LED on but no fault exists. Engine gauges show oil pressure, engine temperature, and frequency (speed) are within normal limits — The monitor board or a sensor may be at fault. | Contact your Dealer or Distributor for service | |
| 14 | Engine starts from generator control panel, but will not start automatically or from a remote panel. (Note: The AUTO/OFF/MANUAL switch must be in the AUTO position for automatic or remote starting) — Indicates possible fault with remote start circuit. | Check the following: Check wire to ATS; See ATS section for further troubleshooting; Contact your Dealer or Distributor for assistance | |
| 15 | Engine will not crank — Indicates possible fault with control or starting system. | Check for the following conditions: Fault lamp on. Correct fault and reset control; Poor battery cable connections. Clean the battery cable terminals and tighten all connections; Discharged or defective battery. Recharge or replace the battery; Contact your Dealer or Distributor for assistance if none of the above | |
| 16 | No AC output voltage — Indicates possible fault | ||
| 17 | Overcrank LED | Check for empty fuel tank, fuel leaks, or plugged fuel lines and correct as required. Check for dirty fuel filter and replace if necessary (See Maintenance section of Engine Manual). Check for dirty or plugged air filter and replace if necessary (See Maintenance section of Engine Manual). | |
| 18 | Engine Over-speed LED | Refer to governor adjust procedure. Contact your Dealer or Distributor for service. | |
| 19 | Unit Not In Auto LED | Move the AUTO/OFF/MANUAL switch to the AUTO position for automatic starting. | |
| 20 | Low Fuel LED | Check fuel level and replenish as required. See Engine Manual for fuel system priming procedure. | |
| 21 | Low Coolant Temperature LED | Check for the following conditions: Coolant heater not connected to power supply. Check for blown fuse, open circuit breaker or disconnected heater cord and correct as required. Check for low-coolant level and replenish if required. Look for possible coolant leakage points and repair as required. | |
| 22 | Charger Malfunction LED | Check and repair. Contact Dealer or Distributor for assistance. | |
| 23 | Low Battery LED | Check electrolyte level and charger output or replace the battery. | |
| 24 | Fault LED on but no fault exists. Engine gauges show oil pressure, engine temperature, and frequency (speed) are within normal limits. | Contact your Dealer or Distributor for service. | |
| 25 | Engine Start from Generator Control Panel but will not start automatically or from a remote panel. | Check the following: Check wire to ATS. See ATS section for further troubleshooting. Contact your Dealer or Distributor for assistance. | |
| 26 | Engine will not crank. | Check for the following conditions: Fault lamp on. Correct fault and reset control. Poor battery cable connections. Clean the battery cable terminals and tighten all connections. Discharged or defective battery. Recharge or replace the battery. | |
| 27 | No AC Output Voltage. | Verify output with another meter if ok check meter, if ok check meter fuses. Regulator fuse is blown. Replace fuse. Contact your Dealer or Distributor if voltage build-up causes fuse to blow. Check rotating rectifier for damaged diodes. Replace all diodes if any are failed. | |
| 28 | No Engine Start. | Check Engine Start connections. Investigate why the Engine Control Switch was put in Manual. Contact your Dealer or Distributor for assistance. | |
| 29 | No Engine Stop. | Check Engine Start Timer setting. Check Engine Start Connections. Investigate why the Engine Control Switch was put in Manual. Contact your Dealer or Distributor for assistance. | |
| 30 | ATS will not transfer to Emergency. | Check Engine Start connections, Generator output, and Engine Control Switch. Plug in Power Supply harness. Plug in Limit Switch harness. Check transfer to Emergency Timer setting. Contact your Dealer or Distributor for assistance. | |
| 31 | ATS will not transfer to Normal. | Check Utility and Utility breakers. Plug in Power Supply harness. Plug in Limit Switch harness. Check retransfer to Normal Timer setting. Contact your Dealer or Distributor for assistance. | |
| #14 | PRE-HI ENGINE TEMP LED. Engine continues to operate — Indicates engine has begun to overheat and engine temperature has risen to approximately 215°F (105°C). If generator is powering non critical and critical loads and cannot be shut down. Use the following: | Reduce load if possible by turning off non-critical loads; Check air inlets and outlets and remove any obstructions to airflow; Open doors or windows in generator area to increase ventilation; If engine can be stopped, follow procedure in Step 2 | |
| *3 | PRE LOW OIL PRESSURE LED. Engine continues to operate — Indicates engine oil pressure has dropped to 20 psi (138kPa). If generator is powering critical loads and cannot be shut down, wait until next shutdown period and then follow Step 4 procedure. If engine can be stopped, follow procedures in Step 4. | ||
| *7 | UNIT NOT IN AUTO LED — Indicates AUTO/OFF/MANUAL switch is in the OFF position which will prevent automatic starting if an automatic transfer switch is used. | Move the AUTO/OFF/MANUAL switch to the AUTO position for automatic starting | |
| *9 | LOW FUEL LED. Engine shuts down and LOW OIL PRESSURE LED — Indicates engine has run out of fuel. | Check fuel level and replenish as required. See Engine Manual for fuel system priming procedure | |
| *10 | LOW ENGINE TEMPERATURE LED. Set is in standby mode but not operating — Indicates engine coolant heater is not operating or is not circulating coolant. | Check for the following conditions: Coolant heater not connected to power supply. Check for blown fuse, open circuit breaker or disconnected heater cord and correct as required; Check for low coolant level and replenish if required. Look for possible coolant leakage points and repair as required; Contact your Dealer or Distributor if none of the above | |
| *11 | CHARGER MALFUNCTION LED. Unit continues to run — Indicates possible fault with the battery charging system. If LED is on only when unit is running indicated problem with battery charging alternator. | Check and repair. Contact Dealer or Distributor for assistance | |
| *12 | LOW BATTERY LED — Indicates starting battery voltage is low. | Check electrolyte level and charger output or replace the battery | |
| SPN 38 FMI 3 | Fuel Level Sensor 2 Circuit Voltage Above Normal or Shorted High | ||
| SPN 38 FMI 4 | Fuel Level Sensor 2 Circuit Voltage Below Normal or Shorted Low | ||
| SPN 84 FMI 1 | Vehicle Speed Sensor (VSS) Data Valid but Below Normal | ||
| SPN 84 FMI 2 | Vehicle Speed Sensor (VSS) Data Erratic, Intermittent or Incorrect | ||
| SPN 84 FMI 3 | Vehicle Speed Sensor (VSS) Voltage Above Normal or Shorted High | ||
| SPN 84 FMI 4 | Vehicle Speed Sensor (VSS) Voltage Below Normal | ||
| SPN 96 FMI 3 | Fuel Level Sensor 1 Circuit Voltage Above Normal or Shorted High | ||
| SPN 96 FMI 4 | Fuel Level Sensor 1 Circuit Voltage Below Normal or Shorted Low | ||
| SPN 65559 | SPN 65559 is set | Refer to SPN 65559 | |
| SPN 66001 | Engine does not crank | Refer to SPN 66001 | |
| SPN 66002 | Engine does not crank (if equipped) | Refer to SPN 66002; if the vehicle is not equipped with an ECM controlled starter relay, repair the starting system |
Compiled from General Motors service manuals and controller documentation. Cause/remedy shown where extracted; always verify against the manual for your exact model.
HI ENGINE TEMP LED. Engine shuts down — Indicates engine has overheated (engine temperature has risen above 225°F/110°C) or coolant level is low (sets with coolant level sensor).. Remedy: Allow engine to cool down completely before proceeding with the following checks: Check coolant level and replenish if low. Look for possible coolant leakage points and repair if necessary; Check for obstructions to cooling airflow and correct as necessary; Check for a slipping fan belt and tighten if loose; Reset control and restart after locating and correcting problem. Contact your Dealer or Distributor if none of the above.
LOW OIL PRESSURE LED. Engine shuts down — Indicates engine oil pressure has dropped to 15 psi (97kPa). NOTE: See also Step 5. Remedy: Check oil level, lines and filters. If oil system is okay, but oil level is low, replenish. Reset control and restart. Contact your Dealer or Distributor if oil pressure is not in the range of 35 to 55 psi (21 to 379 kPa).
OVERCRANK LED. Engine stops cranking. Or Engine runs, shuts down, and LOW OIL PRESSURE LED — Indicates possible fuel system problem.. Remedy: Check for empty fuel tank, fuel leaks, or plugged fuel lines and correct as required; Check for dirty fuel filter and replace if necessary (See Maintenance section of Engine Manual); Check for dirty or plugged air filter and replace if necessary (See Maintenance section of Engine Manual); Refer to Step 4; Reset the control and restart after correcting the problem. Contact your Dealer or Distributor for service if none of the above.
Engine runs and then shuts down, OVERSPEED LED — Indicates engine has exceeded normal operating speed.. Remedy: Refer to governor adjust procedure. Contact your Dealer or Distributor for service.
LOW FUEL LED. Engine continues to run — Indicates diesel fuel supply is running low.. Remedy: Check fuel supply and replenish as required.
Low Fuel LED. Remedy: Check fuel supply and replenish as required..
Unit Not In Auto LED. Remedy: Move the AUTO/OFF/MANUAL switch to the AUTO position for automatic starting..
FAULT LED on but no fault exists. Engine gauges show oil pressure, engine temperature, and frequency (speed) are within normal limits — The monitor board or a sensor may be at fault.. Remedy: Contact your Dealer or Distributor for service.
Engine starts from generator control panel, but will not start automatically or from a remote panel. (Note: The AUTO/OFF/MANUAL switch must be in the AUTO position for automatic or remote starting) — Indicates possible fault with remote start circuit.. Remedy: Check the following: Check wire to ATS; See ATS section for further troubleshooting; Contact your Dealer or Distributor for assistance.
Engine will not crank — Indicates possible fault with control or starting system.. Remedy: Check for the following conditions: Fault lamp on. Correct fault and reset control; Poor battery cable connections. Clean the battery cable terminals and tighten all connections; Discharged or defective battery. Recharge or replace the battery; Contact your Dealer or Distributor for assistance if none of the above.
Overcrank LED. Remedy: Check for empty fuel tank, fuel leaks, or plugged fuel lines and correct as required. Check for dirty fuel filter and replace if necessary (See Maintenance section of Engine Manual). Check for dirty or plugged air filter and replace if necessary (See Maintenance section of Engine Manual)..
Engine Over-speed LED. Remedy: Refer to governor adjust procedure. Contact your Dealer or Distributor for service..
Unit Not In Auto LED. Remedy: Move the AUTO/OFF/MANUAL switch to the AUTO position for automatic starting..
Low Fuel LED. Remedy: Check fuel level and replenish as required. See Engine Manual for fuel system priming procedure..
Low Coolant Temperature LED. Remedy: Check for the following conditions: Coolant heater not connected to power supply. Check for blown fuse, open circuit breaker or disconnected heater cord and correct as required. Check for low-coolant level and replenish if required. Look for possible coolant leakage points and repair as required..
Charger Malfunction LED. Remedy: Check and repair. Contact Dealer or Distributor for assistance..
Low Battery LED. Remedy: Check electrolyte level and charger output or replace the battery..