So I keep getting code p0500. Replaced the sensor and code still there. Od light starts flashing at around 30mph. My Speedo on dash works fine and hasn’t had any issue and I have no abs light on. Checked on FORScan and I’m getting no reading for speed from the vss but looks like it’s got 5v going to it? Not sure what exactly reference voltage is. Is there another sensor that controls the speedometer? I don’t get why it’s showing my speed on the dash but not sending speed signal to the pcm? Any ideas?

 

Also I just checked my abs wheel speed sensors and I’m getting speed readings on both front wheels and the rear diff. So if the rear diff is reading speed why and I getting a vss light?

 

Reference voltage is the 5v signal the pcm puts out to basically every sensor it monitors. The sensors use resistance to preform whatever function they're designed for and as the 5v signal passes through the sensor the varying resistance changes the 5v signal. The pcm reads the returning voltage signal to monitor and alter engine performance. So basically it's it's own language between the pcm and the engine sensors. This is also why solid, clean connections on all electrical components is so critical. Any grime, crud, or corrosion is resistance, which can alter the signal and make the engine run poorly. As for your VSS code, a guess would be the wiring is at fault. The pcm and gauge cluster are independent of each other so it would likely be between wherever the wire splits to each location and the pcm.

 

Wasn't there some issue that occurred when the 3rd brake light was out?

 

And that is not how the VSS works.

The VSS generates a square wave when the tone ring passe through the magnetic field of the sensor. The PCM reads the falling edge of the square wave. Higher frequencies equal higher speeds.

Back to the OP: It is likely that the reading you are getting on your tool is a substituted value that the PCM uses when it can't read the VSS. It doesn't necessarily mean that there VSS signal is present.

I am almost certain that you have a wiring issue between the PCM and the VSS.