General Information |
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ISC, ISL CM554 preheat/post-heat cycle information: The intake air heaters are used in B and C engines to aid starting in cold ambient conditions. There are two phases of intake air heater operation:
The intake air heater is used in starting during cold temperatures and to reduce white smoke after such a start. The intake air heaters or grid heaters are energized or de-energized from two relays controlled by the ECM. The amount of time the intake air heaters stay on in the preheat phase is a function of the intake manifold temperature at key on; preheat time increases with colder intake manifold temperatures. The maximum duration of preheat is 45 seconds and no engine preheat is needed for coolant or intake air temperatures exceeding 4.4°C [40 °F] for ISC/ISL engines. A “Wait-to-Start” lamp is also controlled by the ECM and is illuminated (to indicate that the driver must not crank the engine) while the intake air heaters are activated just after key on, during the preheat phase. During cranking, the intake air heater is turned off to allow maximum current to be used by the starter. The post-heat cycle can operate for several minutes on very cold days before the intake air heaters are de-energized. QSC, QSL CM554 preheat cycle information: The preheat cycle of the electric intake heater varies by ambient temperature and is controlled by the ECM. During the preheat cycle, the ECM sends power to the OEM-supplied “Wait-to-Start” lamp. The operator must not crank the engine until the “Wait-to-Start” lamp is deactivated. Consult the Operation and Maintenance Manual for further details on start procedures. Figure 1 illustrates the intake heater preheat cycle.
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Preparatory Steps |
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Remove |
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Install |
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Finishing Steps |
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WARNING




