on my 99 trans am i got a "throttle position sensor a low input"

what exactly does this mean and how should i go about checking it

 

sounds like the voltage to your tps is low. i believe it's the yellow wire?? dang, can't believe i can't remember. should be about 5 volts. check it with a voltmeter. your ground could be bad. if it's getting ~5v then the sensor is bad i reckon.

 

The code sets for low voltage from the TPS sensor when the throttle blades are closed. On the LT1 cars, it sets if the sensor voltage is below 0.20V (not sure about the LS1 cars). Could mean the sensor is deceased, or the signal wire is corroded or broken. You should be able to probe the 3 wires on the sensor. Typically (check for your specific engine) the black wire is ground, and the grey wire is +5V reference voltage. Probe between those two wires to make sure you have 5V. Then probe between the third wire (typically Blue). At closed throttle you should see about 0.50V and at WOT about 4.5-4.8V.