[poindexter]

I recently got my MPGuino put together and I found that my power door locks cause it to register a VSS signal if the car is off. It is really just an annoyance because when I unlock my car to get in it, it causes the current mpg to go to all 9s and I cannot read what the last trip mpg was. Other than that it works great.

I looked at the VSS voltage with my cheap digital voltmeter and I cannot tell how much the voltage is swinging from the door locks, just that it is. It seems to happen about 70% of the time I hit the locks. I can tell right away because the backlight comes on.

Any ideas? Maybe a high pass filter? Maybe a pulldown resistor on the input? I tried enabling the built in pullup 20k resistor in the code but it prevented the MPGuino from registering any VSS signals.