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Thread: Can't Clear Trouble Codes on VPW protocol?

  1. #1
    Newbie split63's Avatar
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    Can't Clear Trouble Codes on VPW protocol?

    I'm able to read Pending and Trouble codes via VPW, but I can't seem to clear them.

    I send this packet:

    68, 6A, F1, 04, CRC

    The ECU responds with
    48, 6B, 10, 44, 52

    Clearly the ECU got the packet and it has responded....Seems all is well.

    But I if I then check the codes again, they are still there.

    Note that I removed the fault condition before attempting to clear the codes.
    Is this a case of a VPW ECM not supporting this function?
    I have tried it on a 1997 Saturn SL and on a 2003 PT cruiser..(Ya, weird that the Crysler uses VPW) Can't clear the codes on either.

    Looking closely at the Standard J1979, it actually says that "All ECUs shall respond to this request". But it does not actually say that it must carry out the clearing process.

    Thanks,

  2. #2
    VENDOR - ScanTool Vitaliy's Avatar
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    Quote Originally Posted by split63 View Post
    I'm able to read Pending and Trouble codes via VPM, but I can't seem to clear them.

    I send this packet:

    68, 6A, F1, 04, CRC

    The ECU responds with
    48, 6B, 10, 44, 52

    Clearly the ECU got the packet and it has responded....Seems all is well.

    But I if I then check the codes again, they are still there.

    Note that I removed the fault condition before attempting to clear the codes.
    Is this a case of a VPW ECM not supporting this function?
    I have tried it on a 1997 Saturn SL and on a 2003 PT cruiser..(Ya, weird that the Crysler uses VPW) Can't clear the codes on either.

    Looking closely at the Standard J1979, it actually says that "All ECUs shall respond to this request". But it does not actually say that it must carry out the clearing process.

    Thanks,
    Can you post responses to 0100, 0101, 011C, 03 and 07?
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  3. #3
    Newbie split63's Avatar
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    Quote Originally Posted by Vitaliy View Post
    Can you post responses to 0100, 0101, 011C, 03 and 07?
    Here you go...

    48,6B,10,41,00,BE,3E,B8,10,E7
    48,6B,10,41,01,00,07,E1,E1,A3
    No response to 1C
    48,6B,10,43,01,22,00,00,00,00,E3 (TC=P0122)
    48,6B,10,47,01,22,00,00,00,00,8A (TC=P0122)

    and

    48,6B,10,44,52 (Clear Codes response)
    48,6B,10,43,01,22,00,00,00,00,E3 (TC=P0122)
    48,6B,10,47,01,22,00,00,00,00,8A (TC=P0122)

    Thanks,

  4. #4
    Variable Bitrate
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    Whenever a DTC is hard and present it always looks you can't clear the code.
    In fact you do clear it, but before you can read the codes the ecu has reset the code.

  5. #5
    Newbie split63's Avatar
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    Quote Originally Posted by p2psmurf View Post
    Whenever a DTC is hard and present it always looks you can't clear the code.
    In fact you do clear it, but before you can read the codes the ecu has reset the code.
    I introduce the fault and power up the ECU. Then I remove the fault, read the codes, clear the code and then read the code again. But the codes remain.

    Also, from my limited testing, it appears that the ECU is only checking for the fault at power-up. If I introduce the fault after power up, no code is posted.

  6. #6
    Newbie split63's Avatar
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    So what do you think? Is there something wrong, or is this just how these older VPW ECUs operate?

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