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Thread: DTC won't stay deleted.

  1. #1
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    Default DTC won't stay deleted.

    Well, I finally got Tune to read my PCM. I was beginning to think that my PCM was #65,535 out of all the possible combinations. After over an hour of attempts, I realized the "Preparing PCM for reading flash..." light didn't mean anything. I did a series of stops and starts and I finally saw the "PCM not ready, waiting light" and then it started to log and gave a time to go and the bar started to move.
    As the book says, I have several DTCs, low voltage and Reduced engine Power. I went to Scan and under Info deleted the DTCs but after they're all cleared and I disconnect and turn the key off, they come back. I've cleared them several times and the DIC (MIL) still gives the same two (above) codes.
    Would someone please give me a clue on what I'm missing here.
    I've swallowed my pride and expanded on the above so that my experience will maybe help others new to this operation.

    Thanks, Curt

  2. #2
    EFILive Developer Site Admin Blacky's Avatar
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    Default Re: DTC won't stay deleted.

    Quote Originally Posted by curtbriggs
    Well, I finally got Tune to read my PCM. I was beginning to think that my PCM was #65,535 out of all the possible combinations. After over an hour of attempts, I realized the "Preparing PCM for reading flash..." light didn't mean anything.
    Actually the "Preparing PCM for reading" message does mean something. It means that EFILive is attempting to unlock the PCM using the standard GM seed/key (or the key supplied by the user - if the user supplied a key).

    Depending on the state of the PCM, this can take up to 15 seconds. EFILive will attempt three times to unlock the PCM with a 5 second wait between attempts.

    GM included a 10 second delay to prevent brute force attacks (i.e. trying all key combinations) on the PCM security.

    Quote Originally Posted by curtbriggs
    I did a series of stops and starts and I finally saw the "PCM not ready, waiting light" and then it started to log and gave a time to go and the bar started to move.
    If you see the "waiting..." message, do not stop it , allow the PCM timeout to expire (always within 15 seconds) and EFILive will continue.

    Quote Originally Posted by curtbriggs
    As the book says, I have several DTCs, low voltage and Reduced engine Power. I went to Scan and under Info deleted the DTCs but after they're all cleared and I disconnect and turn the key off, they come back. I've cleared them several times and the DIC (MIL) still gives the same two (above) codes.
    Would someone please give me a clue on what I'm missing here.
    I've swallowed my pride and expanded on the above so that my experience will maybe help others new to this operation.
    Thanks, Curt
    If a DTC returns after it has been cleared then it is a valid DTC and should be investigated.
    Is your battery voltage actually low? After an hour of trying you may well have run down your battery.
    Should the reduced engine power message show if your battery is low?
    Have you re-programmed your PCM at all?

    WARNING - do not attempt to reprogram your PCM with a low battery. EFILive will check battery voltage prior to erasing the flash chip and will abort if the battery voltage is too low or too high.

    Regards
    Paul

  3. #3
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    Default Re: DTC won't stay deleted.

    [quote="Blacky"]
    Quote Originally Posted by curtbriggs
    Well, I finally got Tune to read my PCM. I was beginning to think that my PCM was #65,535 out of all the possible combinations. After over an hour of attempts, I realized the "Preparing PCM for reading flash..." light didn't mean anything.
    Actually the "Preparing PCM for reading" message does mean something. It means that EFILive is attempting to unlock the PCM using the standard GM seed/key (or the key supplied by the user - if the user supplied a key).

    I tried four or five 15 minute uninterupted attempts. I would stop and try normal speed, stop and try high speed again. I tried closing and re-opening the PCM log window. Seemed like when I did three rapid starts and starts, it woke it up.


    Depending on the state of the PCM, this can take up to 15 seconds. EFILive will attempt three times to unlock the PCM with a 5 second wait between attempts.

    I waited a minimum of 15 minutes.

    GM included a 10 second delay to prevent brute force attacks (i.e. trying all key combinations) on the PCM security.

    I left the KEY box blank, I could read the seed key on the screen, should I enter that key in the future?

    Quote Originally Posted by curtbriggs
    I did a series of stops and starts and I finally saw the "PCM not ready, waiting light" and then it started to log and gave a time to go and the bar started to move.
    If you see the "waiting..." message, do not stop it , allow the PCM timeout to expire (always within 15 seconds) and EFILive will continue.

    The waiting message didn't show until I did three rapid starts and starts.

    [quote="curtbriggs"]As the book says, I have several DTCs, low voltage and Reduced engine Power. I went to Scan and under Info deleted the DTCs but after they're all cleared and I disconnect and turn the key off, they come back. I've cleared them several times and the DIC (MIL) still gives the same two (above) codes.

    If a DTC returns after it has been cleared then it is a valid DTC and should be investigated.
    Is your battery voltage actually low? After an hour of trying you may well have run down your battery.

    I had a battery charger on the whole time, it started with 13.2 volts and ended at 11.8 volts. The Low Voltage DIC was followed with 0.6 volts.

    Should the reduced engine power message show if your battery is low?
    Have you re-programmed your PCM at all?

    I haven't reprogramed the PCM yet, this was a copy of the stock program to back up.

    WARNING - do not attempt to reprogram your PCM with a low battery. EFILive will check battery voltage prior to erasing the flash chip and will abort if the battery voltage is too low or too high.

    Paul, what battery voltage range is allowed for engine off logging and will a battery charger effect the readings?
    Thanks, Curt[img][/img]

  4. #4
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    Default

    These codes were all communication history codes. I disconnected the battery for a manifold upgrade and after I finished the job and restarted the engine, the codes were gone. System now normal.
    99C5, mn6, Vortec T trim, Snow meth injection, AFR 205s, ARP studs,Comp 224*112*+2*.580", YellaTerra RRs, PRC Ti's w/dbls, Supermaxx LTs, No Cats, Corsa Indys, LS6Intk, Hurst, Fikse Aro18"s. Pilot Sports 315/30,265/35, 04ZO6 Shocks Hotchkis bars, EBC YellowStuff pads, SS hoses, LM-1, EFILive, 2002 OS. RPS dual disc Clutch, DTE Strut Brace & output shaft.

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