2000 Dodge Ram 1500 5.9L. What causes error code P0123 Throttle Position Sensor Voltage High? I have replaced the TPS, due to no voltage at the sensor output. After replacing the TPS, I checked the voltage at the plug, 5.20v input, 0.01 ground and tested the output voltage on the new TPS, also within specs. 0.72 volts at idle, 4.03 volts at full throttle. Yet 50 miles down the road the Service Engine light comes back on with error code P0123. I reset the codes, drove for about an hour and the light came back on again. I also pulled off the connectors at the computer to check for corrosion, dirt etc. Found nothing. Any ideas or suggestions?

 

try another sensor, if you just replaced it , it should be under warranty. For some reason our rams seem to be very fussy when it comes to the tps. If that dosen't fix it check the wiring between the tps and the ecm. all the wiring any nics could be making a short from time to time and setting the code. After that i would try pm'ing steve he is a wealth of info on trouble shooting. Just look around the DF and you should be able to find him.

 

was tps aligned when intalled?

 

I am going to remove the TPS and check it out, and also run resistance checks from plug to plug to look for shorts. Visually everything looks good, but something caused the original TPS to go bad, and something is causing this error code to repeat over and over, so I'll do some old fashioned toubleshooting and see if I can find anything. If that fails....I'll be back. Thanks for the suggestions!

 

I had a neighbor who had a similar problem. I scanned his PCM, and also got a high voltage at TPS error. The thing is, this only occured when he put on his A/C. After some research and checking wiring diagrams, the three wires coming from the TPS go directly to the PCM. No other grounds or interconnections exsist. The problem was the PCM. What happened was, the PCM supplies the 5 volts to the TPS, when my neighbor turned on his A/C, I got 12 volts at the TPS. The PCM somehow shorted internally everytime he turned his A/C on. He replaced the PCM, and had to get it re-flashed at the dealship. No problems since......I hope this helps.....

 

Hello,
I also have the same problem.
I identified it while still on used car warrenty, but not about the A/C switch part. The warrenty expired while I was waiting for the dealer to return my e-mail about the problem. Figures!
I noticed the code P0123 (TPS high voltage error) coming in along with a "sagging", "bucking", when the truck got to about 1600-1800 rpm. Once I got the MAP sensor code as well. When the code(s) came in I also got the check engine light.
I replaced both the TPS and the MAP sensor, even though they metered out well in a static test. I still saw the problems at RPM. Meter checks between the PCM and the sensors looked good.
I pulled the A/C clutch relay in the Power Distribution Center (PDC). All ran well. Replaced the relay in the PDC and disconnected the connector near the fuel rail that goes to the A/C clutch. All went well.
It seemed that anytime the A/C clutch is allowed to engage, the problem shows up. Disconnect anything in between the power and the A/C clutch and the problem goes away.
It looks like you have the correct fix for my problem. I've been searching in this forum for an answer for over a week. I've never used the search combination I've just used, and now I found your answer.
Thanks for your work and your research. I'll try to let you know how I made out.
Who has PCM's for the best price?
Steve

 

Continued this thread under "PCM schematic and troubleshooting notes."