MPGuino quit working... VSS problem?

[cbaber]

I built my own MPGuino and had it working fine for the past couple weeks. The other night I was driving home and the MPGuino fell from the spot where my radio used to sit and seemed to short out the car radio circuit. It blew my radio fuse. I think when it fell the power wires came loose and shorted with something.

Anyway, the Arduino itself is fine. Still powers on. I can still program it. MPGuino comes on like normal. The only change is not its not reading any info. No MPG, speed, or distance data is recording. The only value that works is the Gallons Per Hour. Since GPH is still working we can assume the injector lead is working properly.

So that leads me to believe the VSS input is not working. The speedo in my car works fine. The connection near the ECU was not affected at all during the fall, and the resister soldered onto the end of the wire is within proper resistance.

Next thing I though of was that somehow I burnt out the pin used as the input for the VSS, digital 14 (A0). So I switched the pin used in the programming and tried digital pin 15 as the input. Still not working.

Since everything else, including the pushbuttons, is working fine and it seems only the VSS is not registering this has frustrated me. Anyone else have anything like this happen? Do you have any suggestions on what to check?

PS: Yes i have reloaded the code onto the MPGuino and still no luck...

[JellyBeanDriver]

Do you have a scope to see if the VSS signal is okay from the ECU?

[nickdigger]

His signal is good, since his speedo still works.

You need to trace your vss input on your 'guino. Turn the ign On, and slowly roll the car, while probing the vss input voltage. When it hits 12v (or whatever "High" is), stop the car & check voltage after the resistor. If it never hits "High", then your input wire got disconnected somewhere.

[cbaber]

Originally Posted by nickdigger

His signal is good, since his speedo still works.

You need to trace your vss input on your 'guino. Turn the ign On, and slowly roll the car, while probing the vss input voltage. When it hits 12v (or whatever "High" is), stop the car & check voltage after the resistor. If it never hits "High", then your input wire got disconnected somewhere.

Thanks I never thought about doing this but its a very good idea. I also thought about downloading a computer program that acts as a frequency generator to simulate the VSS signal to make sure its not the MPGuino. Will do both and report the results back. Thanks again.