If you do not have a scanner which will give you the description then you will use a voltmeter.
Testing the TPS
circuit is fairly simple.
With the key on engine off backprobe the TPS
connector signal and signal return wire while it is still connected to the TPS
. That would be the BK/LB and OR/DB wires.
What is the voltage reading? above 3.50 volts? below .40 volts? If the reading is between .40 and .90 slowly sweep the TPS
and watch the voltage, does it rise consistantly as the throttle is opened or did it drop off at any point? If it dropped off at any point during the sweep replace the TPS
. If voltage is high/low......
Disconnect the TPS
connector,with the key on/engine off with 1 lead of your voltmeter connected to a good ground probe the VT/WT wire with the other lead, does the meter read 5 volts? If no repair the 5 volt reference line, if yes....
Probe the VT/WT wire with 1 lead and the BK/LB wire with the other lead, does the meter read 5 volts? If no repair the signal return line, if yes.......
Check continuity on the signal line from the TPS
to the SBEC
cavity # 22, this is the OR/DB wire, if resistance reads over 5 ohms repair the signal return line....
If resistance is below 5 ohms connect 1 lead of the ohmmeter to a good ground and probe each end of the signal line with the other probe, does the ohmmeter read open on both ends? If no, repair signal line short to ground, if yes, replace the TPS
Be aware that the terminals break/crack inside the TPS
connector, and be sure the terminals are not spread open or pushed out.