Mechanical to electrical pulse generator

[jbaker4341]

I’m wondering if this device matters which way it’s wired up? Before hooking up to the Jeep i connected it to a volt meter and spun it with a drill. If I switched the wires on the meter I still got a increase of voltage depending on the speed of the drill. The Jeep seems to run a bit flat now with the new device. Any chance the 2 wires could be hooked up backwards causing an issue? It sends an electrical signal to the pcm.

 

[Torxhead]

On my CJ, with an aftermarket fuel injection it is called a vehicle speed sensor. Both wires from it are the same color, so I would say it doesn't matter. Since you state that it has an effect, you could try swapping the wires.

 

[jbaker4341]

I’m wondering if the pulses per revolution may be different than the original unit causing a change in the way the motor runs?

 

[PistolDave]

If your injection is a Howell TBI (ie 1987-2005 GM) the ECM does not look at actual speed for fuel injection purposes, just whether or not the vehicle is in motion. It does this for defueling control under deceleration (Closed throttle, but vehicle still in motion) as I understand it. Later models (92-95) used speed data to control shifting and torque converter lockup in the early electronic Overdrive transmissions (4l60e).

This again is the way I understand it, but I could be completely mistaken.

If your FI is something other than GM based TBI, none of this applies anyways.

Generally speaking, a square wave generator like that may not be polarity sensitive in an application like this, but you never know.