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Thread: DBW throttle pedal sanity check...P2120, P2122, P2135

  1. #1
    Tuner in Training
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    DBW throttle pedal sanity check...P2120, P2122, P2135

    I am inclined to believe this is a result of a bad connection in the wiring. I have mated a non-GM DBW pedal to the GM DBW harness wiring (6 wires). I have also verified that the Electronic Throttle Position Sensor is not bad (already replaced under warranty....crate LS3 with approximately 1k miles, issue came back with new E-TPS).

    Attached a log from a short drive that ended with the aforementioned DTC's. The failure happens right about 18:00:54.....car was being driving very calmly, was in 4th gear, low rpms, pulling away from a stop light.
    Any constructive input or feedback is welcome if this log is able to reveal something to you. I can see where the issue happens but I cannot interpret much from what I see.

    Upon the DBW pedal going dead, the car entered into a misfire condition. I shut the car down and reset the DTCs, and it started right up like nothing happened and drove on.....until a 1/4 mile down the road, I went over a set of train tracks which either caused the DBW pedal failure & misfire to return or it was one hell of a coincidence. The second failure I didn't even shut the car down, I simply cleared the codes and the misfire vanished and the pedal was restored instantly upon clearing in realtime. This is why I am thinking the obvious explanation is a bad wiring connection, but I'd like an outside set of eyes and brain matter to look at this, in case there is something I could be overlooking.
    29FEB24 00.PNG
    logfile 29FEB24 2.9 DBW failure 01.hpl

  2. #2
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    Attaching the log of the drive over the train tracks as well where I did not shutdown the car at all, I simply cleared the DTCs in realtime.
    29FEB24 01.PNG
    logfile 29FEB24 2.9 DBW failure 02 and reset.hpl

  3. #3
    Senior Tuner
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    So you are using a non-GM accelerator pedal position (APP) sensor? I don’t know that anyone ever gets that to work. It often doesn’t work if you have a GM Pedal/APP that doesn’t match the ETC.

  4. #4
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    Quote Originally Posted by gtstorey View Post
    So you are using a non-GM accelerator pedal position (APP) sensor? I don?t know that anyone ever gets that to work. It often doesn?t work if you have a GM Pedal/APP that doesn?t match the ETC.
    It works, there are 10 other identical cars with the same arrangement. Trying to figure out why this one is having issues.

    AGAIN, I believe the most likely issue is a wiring connection, I'm just looking for an outside perspective that may see something in the log that I am missing...for example am I even logging (all) the right parameters to more accurately figure out what is going on, rather than just blindly re-wiring everything and assuming the issue will go away.