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Thread: Differences between the DTCs mode 3 and DTCs mode 7 in CAN

  1. #1
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    Differences between the DTCs mode 3 and DTCs mode 7 in CAN

    Hi!!
    What are the differences between the DTCs mode 3 and mode 7 in CAN?

    In SAEJ1979 The mode 7 sais: The purpose of this service is to enable the external test equipment to obtain “pending” diagnostic trouble codes detected during current or last completed driving cycle.

    The mode 3 sais: The purpose of this service is to enable the external test equipment to obtain “confirmed” emission-related DTCs.

    But I don´t undestand this. What are the diferences between "pending" DTCs and "confirmed" DTCs?

    Thanks!!

  2. #2
    Constant Bitrate joeyoravec's Avatar
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    Quote Originally Posted by proyectanteATE View Post
    But I don´t undestand this. What are the diferences between "pending" DTCs and "confirmed" DTCs?
    The PCM may set a pending trouble code the very first time a problem is detected. It might not set a confirmed trouble code (and light the MIL) until the same problem is observed repeatedly so the engine controller is quite certain that the problem exists.

  3. #3
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    Thanks Joe for the information!!

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