Using an autometer speedometer...
I've run the output wire from the PCM to the SIG port on the Autometer Speedometer and the gauge does not show any speed. In hptuners the scanner shows accurate speed when compared to a GPS app on my phone. Transmission shifts appropriately.
I spliced the VSS wire from 4l80e directly to the speedometer SIG port. Upon moving the vehicle the speedometer gauge and hptuners speedometer gauge swings radically providing an inaccurate speed. Also my transmission shifts unpredictably because it relies on the VSS signal to shift the transmission. Upon unplugging the wire from the sig port, the transmission and speed on hptuners returns to normal.
Note: in both settings above the autometer gauge does light up when it receives power and displays 16000 for a brief moment then the mileage.
Can anyone point my in the right direction,
thanks.





