So today, I applied a tiger patch to a hole in my tailpipe. I jacked the truck up, applied the patch, dropped the truck and idled it for about 20 minutes. I then drove to the gas station down the street, and my speedometer is not working. Tach, temp, volts, oil pressure, and fuel all working. I also have a cheap little HUD that plugs in to obd port that displays speed. It also reads 0. No check engine light or any other problems. Ideas? It is a 2000 Dakota, 4wd, 3.9 engine.

 

What year is your truck? What trans?

 

Maybe your speed sensor?

 

Is your transmission shifting? It's your VSS (vehicle speed sensor). If it fails, it just doesn't send a signal for the transmission to shift. Since your computer doesn't know there's SUPPOSED to be a signal, it doesn't know the VSS isn't working. When you jacked the truck up, you might have knocked a wire loose.

 

Transmission seems to shift fine once I am up to speed. It did falter a couple times going up a mild hill on the way to work this morning. Planning to pick up a new sensor after work today.

 

2000 I think will still have the VSS on top of the rear axle. It's a special braided pair of wires running up the driver frame rail.