Wait to Start Preheating: Intake Air Heater Control on Cummins INSITE Software (CUMMINS Engines)

Intake Air Heater

Figure 1.1 - Wait to Start Preheating (Murphy PowerView)

If the Engine ECU is broadcasting a 'Wait To Start' message, this screen will be shown. Engine

manufacturers typically recommend against starting the engine while this message is broadcasted from the ECU. Once the ECU stops broadcasting this message, this screen will no longer be displayed.

Intake Air Heater Control
The air intake heater control helps the combustion process while starting in cold temperatures by controlling the heating elements in the engine's intake air system. The ECM controls the heating elements in two phases, pre-heat and post-heat. The amount of time that the intake air heater remains on depends on the intake manifold temperature at key On.

Pre-heat (after key On and before cranking): At key On, the ECM checks the intake manifold air temperature. Based on this temperature, the ECM lights a Wait to Start lamp and energizes the intake air heaters (as Figure 1.1 above). After a calibrated period of time, the ECM turns off the intake air heaters and the Wait to Start lamp turns off. Once the lamp is off, the operator can crank the engine. Pre-heat time increases with colder intake manifold air temperatures.

Post-heat (after successful engine starting): During cranking, the intake air heater is turned off to allow maximum current for the starter. The post-heat phase starts after a successful engine start. The ECM cycles the heaters based on the intake manifold air temperature at key On. This cycle can operate for several minutes on very cold days before the heaters are de-energized. The post-heat phase controls white smoke after startup.

#Features and Parameters

Figure 1.2 - Intake Air Heater (Enable)

This feature controls the heating elements, which will turn on and heat the intake air in cold temperatures.

Depending on the application, the engine may have 1 or more intake air heaters. The heaters are controlled by the ECM via a relay connected to the battery supply. During the post-heat phase after the engine has started, the ammeter gauge may fluctuate during the automatic cycling of the intake air heaters.

To eliminate the possibility of hard starting in cold ambient temperatures, the operator should wait for the Wait to Start (as Figure 1.1 above) lamp to turn off before attempting to start the engine.

#Intake Air Heater Override

This test enables you to override the intake air heater controls and manually turn ON or OFF the intake air heater solenoid(s). This is useful for troubleshooting and diagnosing startability, white smoke issues, and intake air heater fault codes. When the relays are energized, an audible click should be heard.

For some engines, grid heaters for 12V systems are wired in parallel with two drivers, and each driver controls only one grid heater. Grid heaters for 24V systems are configured in series, with one driver controlling both grid heaters. Consequently, the second driver is not used for 24V systems and does not display in INSITE.

The intake heater(s) could be on with just key-on (pre-heat cycle), depending on the intake air temperature. They will pre-heat up to an intake manifold temperature of 66 degrees F.

To prevent burn out of the intake air heaters, some engine applications use a timer that turns off the heaters even though they are commanded on. For those applications that don't use a timer, the Intake Air Heater Override Test must turn them off after a short time.

To test the elements of the intake air heater:

1). Connect adapter tools to diagnostic port on Cummins Engine. Read More: How to Connecting CUMMINS Engines using Cummins INSITE Software.

2). Select Intake Air Heater Override from the list in the ECM Diagnostic Tests Wizard window.

Figure 1.3 - Intake Air Heater Override

3). Click Next, and the Intake Air Heater Override window opens.

Figure 1.4 - Intake Air Heater #1

4). Click Start to begin the test.

Figure 1.5 - Test is Running (Start)

5). Click in the checkbox(es) to turn an Air Heater ON or OFF for testing. The Air Heater will be activated for a predetermined time, depending on the calibration.

Figure 1.6 - Test is Running (ON)

6). Click Stop to stop the test.

Figure 1.7 - Test Stopped

→Capture any messages or warnings in the Instructions box.

7). Click Back to exit the test.

#Additional Information:

→The Intake Air Heater will stay on for a maximum of 180 seconds 

→A click should be heard if the Intake Air Heater is operative 

→If required, select Stop to end the test early 

→If ECM Communication Lost. All parameters will return to their original value when keyswitch is turned off.

Read More:

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