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MIL Lamp Strategy

I/M Readiness OK to test = Key On Engine OFF -  MIL Lamp will remain on until the vehicle is started or Ignition is turned off.

I/M not ready for testing = Key On Engine OFF  MIL Lamp on solid for (15) seconds then MIL Lamp will flash on/off for (5) seconds then it will remain on until the vehicle is started or the Ignition is turned off.

In order to meet mandated regulations, a new feature has been added to engine control modules to provide an OBDII I/M (In-Field Inspection & Maintenance) readiness Indicator. When the engine controller is in in-field mode, turning the key on with the engine off will activate the MIL light for approximately 15 seconds. After this time, if the vehicle is ready for I/M testing, the MIL light will remain fully illuminated. If the vehicle is not ready, the MIL light will blink for approximately 5 seconds and then remain on until the first engine crank or the key is turned off. This differs from the previous behavior of the MIL light, which was only activated with a failure in the system. For in-plant mode, the MIL light will function as in previous model years. Below are diagrams of how the MIL will operate.

Fig 1: Illustrating MIL Operation
G03137332Courtesy of DAIMLERCHRYSLER CORP.