Problems with VSS / Speed Sensor Pulse
 

Wondering if swapping a engine (same one just less miles) would have any affect to the speed sensor pulse (or something could have affected it in the process). Just got my engine replaced and my navigation unit is not working properly because of the speed pulse (i have a wire going from the navigation unit tapped into the speed sensor wire so the nav know how fast i am going and when i am moving for better accuracy)

My speed gauge on the dash seems to work fine though. however, on my navigation i have a "test connection" screen and even when the car is stopped i get some activity from the speed pulse saying that the car is moving and when i am moving the speed on the nav will drop to 0 then back up to my driving speed. I reset the nav and all that and i get the same thing.

Anyone have any ideas? ... thanks in advance.

Edit: i have a 2000 blazer s-10

If it happened after changing a motor all I can think of is they forgot to attach a ground. Check in back of the drivers side cylinder head, ought to be two coming out of the engine harness there that are supposed to be bolted to the backside of that head, one of them could have an impact on this.

Will do, thanks