If the tps is bad what problem may i see - 1988 Oldsmobile Cutlass Ciera

By tester, do you mean you have a P012x/P022x code from a code reader? If so, be sure to verify that the TPS itself is bad, and that you don't have a circuit (wiring) problem.
RockAuto lists the TPS as a separate part, so if it does turn out to be bad, you should be able to replace just the TPS. Some cars require that the TPS be calibrated with the ECM after installation; don't know about yours.

Did you watch the TPS numbers on a scan tool in your car?
TPS code means TPS bad or wiring or TPS adjustment.
Change the TPS as they cost nothing and do wear out.

Year make and model please. If you have a drive by wire. Could be a bad connection at the TPS or the TPS itself. The TPS is the sensor mounted to the gas pedal. My guess would be a bad connection or corrosion.

That really depends on the car you are trying to check on. The older cars didn't even have a TPS. The best way to see an early indication of the TPS going bad, is how the vehicles is running or responding to your input. First, I suggest putting the vehicle on a diagnostic machine. Go to your nearest Autozone and they will do a check for free. There are 2 indicators that can tell you if you need to replace your TPS, or your IPV.It is easy to confuse the 2 because they kind of do the same thing when your car is running. TPS, or Throttle Positioning Sensor, effects what your throttle does when you depress the accelerator. For example: If your car is idling smoothly and you step on the gas peddle, and the RPM's drop quickly before they rev up. That is a good indication of a bad TPS. IPV, or Idle Positioning Valve, controls your RPM's as the vehicle is idling. If the IPV is bad, then you will experience rough, and fluxuating RPM's when you don't press on the gas peddle. Sometimes, if the IPV is bad, it will cause the vehicle to lunge forward while the vehicle is in gear.

old post. but....
a great question, but on a tracker , the TPS , has 2 parts inside
cascaded as one part. so that makes answers harder.
the tests are here.
http://www.fixkick.com/sensors/tests/TPS-testing.html

1. idle switch bad, means, idle never regulates.
2. end idle side.
3. throttle angle side, is complex. (as seen in scan tool)
4. it detects drivers fast right foot actions and enriches fuel this prevents the hesitation, when you accelerate. if bad it does just that. but does still have full power up hills (after small hesitation) due to the MAF sensor seeing reality and correcting the TPS (errors) see?
5. the TPS also triggers. cut fuel mode when you decelerate,
6. and triggers cut off of EGR and .
7. and triggers , anti snap your next mode , when you decelerate too fast it adds air via the ISC to prevent violent Deceleration.
8. I told you it was complex the FSM book from Suzuki and GEO both stated all that. on the TPS page.

get the Factory Service manual, real, and see those pages.

i had the same car.... what mileage.... 200K?
TPS errors. (its real its a real measured error)
this error is catastrophic, , meaning, not just a tad off,
the FSM covers this in details.
clock spring, the Air bag clock spring? has nothing to do with this.
or do you meant the throttle return spring, (my guess?)
the TPS output pin was discovered to have an illegal high voltage
on the output (you can be sure it idid)
spec:
TP Sensor indicated more than 4.50v for 700 ms.

caused by a bad TPS ground wire, or the output pin cut.
or the TPS internals are cracked in half (bad inside) (i have photos)
its bad TPS or bad wires to it. simple huh?
it will not be a bad ECU. as is on the list; it will not.
The jeep has great cheap TPS to buy ofter market,
on other cars not, and can cost $300 , for them
i connect my potable scope and watch the TPS output while i drive.
and find out if it is really truly bad.... hell the part, costs more than my
scope.!
be happy its not new car with throttle by wire, !!!
or the big V8 , whole new throttle body for $1000

recap. bad TPS, bad wires.

the tps on most cars are calibrated.
if you just thrown on a new TPS and not calibrate it, that is
a big failure.
here are the steps
1 key off
2 remove TPS.
3: put back new.
4:
The TPS is mounted to the throttle body. The throttle shaft end of throttle body slides into a socket in the TPS. The TPS must be installed so that it can be rotated a few degrees. (If sensor will not rotate, install sensor with throttle shaft on other side of socket tangs). The TPS will be under slight tension when rotated.

1. Install TPS and retaining screws.
2. Tighten screws to 7 Nm (60 inch lbs.) torque.
3. Connect TPS electrical connector to TPS.
4. Manually operate throttle (by hand) to check for any TPS binding before starting engine.

adjust the TPS for
0.26 volts at minimum throttle opening (idle)

worst case:
the FSM says it auto calibates
if the new TPS errors,. set it to 1/4 volt at idle.
reset ECU , all DCTs using scan tool
pull battery for 5min neg. lug (backup radio codes first)
put back lug
start engine, drive 25miles or till CEL comes on (failures)

One thing to check is make sure you have a steady 5v to the tps and a constant ground clear the engine computer turn the key on push the gas pedal to the floor about 50 to 100 times if your 5v does not change and you have a good ground and the code returns the tps is bad

this is an obd2 trouble code table, it can help you understand the meaning of code.
and for p0120
the Causes:
Sticking throttle return spring
MAP or TPS connector corrosion
Misrouted harness causing chafing
Bad TPS
Bad PCM
Possible Solutions:
If you have access to a scan tool, with KOEO (Key on engine off) observe the TPS voltage. With throttle closed, voltage should be about .45 volts. It should gradually sweep upwards to approximately 4.5 to 5 volts as you depress the throttle. Sometimes only a scope can capture an intermittent glitch in the TPS signal voltage. If you notice a glitch in the TPS sweep voltage, replace the TPS.
NOTE: Some TPS sensors require fine adjustment. If you aren't comfortable with using a DVOM (Digital Volt Ohm meter) to adjust the new TPS, then it's best to take the vehicle to a shop. If the voltage is not .45 volts (+or- .3 volts or so) with the throttle closed or if the reading is "stuck" then unplug the TPS connector. With KOEO check for 5 volts reference voltage present at the connector and a good ground. You can check the signal circuit for continuity by jumping a fused wire between the ground circuit of the TPS connector and the signal circuit. If the TPS reading on the scan tool now reads zero, then replace the TPS. However if that doesn't change the reading to zero, then check for an open or a short on the signal wire and if none is found, suspect a bad PCM. If manipulating the TPS wiring harness causes any change in idle, then suspect bad TPS.

Not likely getting a bad TPS.Your TPS runs off a 5volt reference wire.Using multimeter with key on engine off Check to make sure you have your 5volt reference check for any deformed terminals or broken wires inside insulation.

po121 means that there is a problem with the throttle position sensor ( tps). or in the wiring or connector, most likely its the tps that is bad. first remove connection from tps, heres how to test. use an ohms meter and hook a lead to top or bottom terminal of tps. use other probe on center terminal of tps. move throttle plate slowly, if the needle on meter does not move at a smooth pace, then tps is bad. good-luck!!