The PCM does a voltage drop test of it's own at the TPS so it knows where the throttle is, and the speed of its movement, based on the voltage amount and speed of change it see's across the resistor inside the sensor as the wiper moves over it.

A 91 Dodge Spirit has its check engine light on, trouble code 24 is found in memory. Code 24 is defined as TPS Volts high, which means the PCM is seeing high volts on the signal line from the TPS when it shouldn't. So what can cause this? A TPS stuck at WOT? Unlikely. How about a short to power somewhere in the wiring? Possible. Do you run to the flow chart for the code and run the tests? Most would. Its very simple to check voltage at the TPS, first the reference volts, then signal return, if both of these show the same reading, check the ground for voltage drop, you should see .1 or less, if its any higher you have a poor ground to the sensor. If its shows full reference voltage, there is no ground to the sensor at all. If the ground checks ok, the sensor is open internally.

This is an open view of a typical tps sensor, the wiper, (signal return) sweeps across the internal resistor sending the volts it sees as it moves across it to the PCM.

Check the 5 volt ref first.

Then look at the signal return.

Finally, look at the ground, if all three are equal, this is a definite bad ground, 5volts in, and 5volts out on both sig return and ground, if the sensor was open internally, there would be no reading at the ground terminal at the sensor.

When you find a sensor with no ground at all, check the wires for stretchy at the tps connector, you may find the wire broken inside the wire jacket just behind the connector.If not, start voltage drop testing the wire back as far as you can, then you will need to voltage drop the ground out of the computer, if you find it good at the computer, you will need to look for a break in the wire from the computer out to the point you ended at the sensor wire.

That was the case here, the wire gives itself away by the perfect 90 degree bend in the ground wire.

Pulling on the wire will reveal if its broken inside the jacket, it will feel stretchy, if you can pull the insulation apart, its for sure.