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Thread: Cannot get idle p/n commanded to match the tune

  1. #1
    Senior Tuner 04silverado6.0's Avatar
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    Cannot get idle p/n commanded to match the tune

    C10 swap p01, dbc. Changed idle p/n to 800 and commanded stays at 750 in p/n and gear. Has a 4l60e and will not crank in gear so the p/n switch should be functioning.
    Attached Files Attached Files

  2. #2
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    GEN 3 ECM's do not handle the starter. That is a separate circuit. So because it starts isn't a check if the PN switch is working. You can log park neutral status.

    Most swaps are wired for PN only. [ECM] 700 has to be changed to PN when it's done like that.
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  3. #3
    Senior Tuner 04silverado6.0's Avatar
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    I can manually shift to 3 from D but that is the limit of the shifter travel. Ill check p/n status tomorrow. Im having a large cam stock converter issue that could use a higher idle in park vs gear.

  4. #4
    Advanced Tuner abc's Avatar
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    Did you ever have it in park during the log you posted?
    If your gear selector is not traveling through the entire range, that's the first place to start. The gear selector switch on the trans. will need to tell the PCM it's in park/neutral.

  5. #5
    Senior Tuner 04silverado6.0's Avatar
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    Should have been in park at the end of the log. I thought that log had a portion of me changing gears with the rpm dropping in gear and shooting up in park.

  6. #6
    Advanced Tuner abc's Avatar
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    Well if it was in park at the end, the PCM didn't know it. I believe the log was still reporting the in gear desired idle rpm. Which I assume is your reason for posting this thread. See what happens if you remove the shift linkage and run the gear selector switch by hand and see if you can get the selector switch to report to the PCM that the trans is in park. If not, sounds like you need to diagnose the gear selector circuit. I also assume you know better than I do but, I don't think there is any magic in the .HPT file that will fix this, short of having a jacked up OS, wrong segment swap, or wrong trans selected.

    Has the gear selector switch ever been off of the trans? Is it a factory switch? I know a lot of those old ones had the connectors glued together and if the first person to remove it didn't know the procedure to removing it, things get broken.

  7. #7
    Senior Tuner 04silverado6.0's Avatar
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    Looked this morning there is no switch on the trans. Explains a lot.

  8. #8
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    Some are done with a switch on the shifter.
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  9. #9
    Senior Tuner 04silverado6.0's Avatar
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    I did confirm in the scanner stays on d4 in all ranges.

  10. #10
    Advanced Tuner abc's Avatar
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    Quote Originally Posted by 04silverado6.0 View Post
    I did confirm in the scanner stays on d4 in all ranges.
    That would explain it. Now the conundrum is figuring out why? I'm interested in knowing the answer once you figure it out.

  11. #11
    Senior Tuner 04silverado6.0's Avatar
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    I think the person who did the swap just did not hook it up. One of the cleanest installs under the hood ive seen by far. Ive found that guys who do swaps usually know little about the pcm control and often leave out important components or choose bad parts. When one of my customers is doing a build i normally give them a list for fuel system components, sensors, anything that could require tune rigging if not chosen wisely.