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Thread: Vehicle Speed Issue

  1. #21
    Tuner in Training
    Join Date
    Feb 2019
    Posts
    18
    VSS status: Yes, it was only a concern as a possible cause of cruise control operation. The VSS is a stock sensor and giving speed to the TCM. The ECM and TCM are talking. I know this because the ECM is putting out a speed signal through C1 pin 21 (this wire leads to the instrument cluster speedometer). I titled this thread "Vehicle Speed Issue" because I originally thought it was the issue because I couldn't see vehicle speed in VCM Scanner and assumed there was a problem there not allowing the cruise to work. I still can't see vehicle speed in VCM Scanner, but that is OK. The ECM is in fact seeing the speed, just not putting it out to see on the OBD2/DLC port. My guess is this is because C1 pin 16 is not wired to the OBD2/DLC. At this point, I'm not worried about it.

    The cruise control works now. Thanks again!

  2. #22
    Tuning Addict blindsquirrel's Avatar
    Join Date
    Apr 2017
    Location
    Meridian MS
    Posts
    7,447
    Which channel are you logging - Engine RPM or Engine RPM (SAE)? If you want to do any further airflow/spark/trans tuning, not having RPM in the logs will make a lot of stuff not work.

  3. #23
    Tuner in Training
    Join Date
    Feb 2019
    Posts
    18
    My tuning knowledge is limited and I don't know how to even tell which channel or RPM it is logging. I do know, using the compare function, that the tach output currently is set to Crank type and a res high of 3 and a res low of 3. The stock tune has output set to Frequency type and a res high of 2 and a res low of 2. I imagine this might be why the tach doesn't work. I've read where pull up +12v with a 1k ohm resistor is needed, but Dakota Digital states this isn't required when using their VHX box. I'll likely need to change the output back to stock.