Testing the Vss

[zth2000]

I am having problems with my ABS as listed in a previous post. I am trying to verify the inputs to the module. Sensors test ok. I am trying to test the Vss. The truck is lifted off the ground, the harness is disconnected from the ABS module and I am reading between the E pin and ground. With the truck in reverse and allowing the tires to spin aprox 10mph I get an AC reading of 6V. It doesn't seem to vary at different voltages for different speeds with the exception of 0V at 0mph. Where am I going wrong?

[71GMC_3/4T]

VSS is probably frequency specific, and a 12V square wave at any frequency looks about the same voltage wise.

 

If your meter has a freq setting, try that to see if it changes with speed.