SPRING 1799756 - Caterpillar

System Operation Description:This procedure can also be used to troubleshoot the following components:
The air inlet heater
The air inlet heater relay
The lamp for the air inlet heaterThe air inlet heater is used in order to improve the engine's ability to start when the engine is cold. The air inlet heater also reduces white smoke at start-up.The ECM controls the operation of the air inlet heater and the ECM controls the operation of the lamp for the air inlet heater through the air inlet heater relay.The operation of the air inlet heater is determined by three different cycle times:
ECM Powerup and Preheat Cycle
Cranking
Engine StartedThe cycle time is determined by the following items:
Engine parameters
Vehicle speed
Service brakeEffects of Vehicle Speed on the Operation of the Air Inlet Heater and on the Operation of the Brake Pedal Position.The air inlet heater is turned off when the brake pedal is depressed and the vehicle speed is equal to 8 km/h (5 mph) or greater than 8 km/h (5 mph).If a diagnostic code for the vehicle speed sensor is active, the ECM will assume that the vehicle speed is above 8 km/h (5 mph). If an active diagnostic code is triggered for the vehicle speed sensor, the ECM will disable the heater when the brakes are applied.The ECM Powerup and Preheat Cycle.The lamp for the air inlet heater should turn on for a minimum of 2 seconds when the ECM is first powered up. The lamp should turn on regardless of the coolant temperature. The ECM will signal the air inlet heater to stay on for 30 seconds if the sum of the coolant temperature and the inlet manifold air temperature is less than 25 degrees Celsius or 109 degrees Fahrenheit.The air inlet heater and the lamp for the air inlet heater should turn on. The air inlet heater and the lamp for the air inlet heater should turn off when the cycle is complete.The ECM will control the air inlet heater during engine cranking if the operator starts the engine before the end of the heating cycle.Control of the Air Inlet Heater During Engine CrankingIf the sum of the coolant temperature and the inlet manifold air temperature is less than 25 degrees Celsius or 109 degrees Fahrenheit, the air inlet heater will turn on when the engine is cranking. The heater will remain on while the engine is cranking. The air inlet heater will reactivate for 30 seconds if the engine fails to start.Engine Start CycleThe operation of the air inlet heater is determined by the coolant temperature and the inlet manifold air temperature after the engine has started. If the combined temperature is less than 25 degrees Celsius or 109 degrees Fahrenheit, the engine start cycle begins. The engine start cycle has two segments:
Continuous Mode
On/Off Cycling ModeThe Continuous Mode lasts for a maximum of seven minutes. The On/Off Cycling Mode can last for a maximum of thirteen minutes. The air inlet heater is turned on and the air inlet heater is turned off