My truck has been running like crap so I decided to clean the throttle body and verify TPS voltage and correct if needed. I've set TPS many times but never encountered this. With the multimeter set for vdc I get 11.48 every time and it will go down to around 9.5 at wot. In short I was using vdc and the key was on- am I forgetting something or is this a sign of a bad sensor? Thanks.

 

I was thinking the supply voltage for the tps was 5.0 volts. Sounds like there is a wiring problem, or an ecm problem. Verify that you are checking the correct wire.
One wire to the tps should be souce, one ground, and the other the signal, so the signal should be between the source voltage and 0. Also verify that your ground or common on your meter is connected to a valid ground, or the common wire on the tps.


Winford

 

You should have between .05 and 1.0 volts at idle. Try to adjust it as close to 1.0 volt as possible but dont go over 1.0 volt (.96 - .99 works good). Adjusting it sometimes requires elongating the holes in the tps sensor. Adjusting it is not necessary if your in range but it will give you better response, and a bit more power since the computer will see more voltage at WOT, and will send out more a longer injector pattern and spark. I usually stick a needle in each wire and attach my voltmeter to the needles. By the way you can check this with the engine off - key on, and you should see a steady increase in voltage as the throttle is opened. If the voltage is not steady as you open the throttle, the tps needs to be replaced. I dont remember which two wires are the outputs to check, but you will get about 5 volts across two of the wires that will not change (this is the input for the tps).
Hope this helps.