I have the 2002 Dodge Ram 1500 Sport with the 5.9L. I recently replaced the intake manifold and plenum gaskets. After getting it all put together, I'm getting a p0123 code (high voltage input switch A). I replaced the tps and the same code remains. I pulled out my meter, checked the ohms in the tps which is on par at max 5ohm with steady increase/decrease. I'm assuming the new tps is fine. I ran a voltage check to my supply line and received a reading of 10.2V when this should be max 5V. Thinking it was the connector, I moved further down the line and same volt reading. Where could this extra voltage be coming fron?

 

Gotta be a short to voltage somewhere..... Gonna have to follow the wires, and see where they go.

 

I tested my lines on ACV and was reading high, after switching to DCV my supply line was 5.23V which is within manufacturer's variance oh +/-.5v as well with the return line under 4.36v. Turns out that when a faulty tps throws the p0123 code and you replace the tps, you either have to take it through a full drive cycle