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98 XJ p0700, p0122

Professor_brap

NAXJA Forum User
Location
OHIO
Alright, need some help. Got P0122, p0700.



New clock spring, clean grounds and battery connection, good battery, new good tested tps, runs a drives fine, light just drives me nuts.



Pulled horn fuse, light comes right back on for those codes.



Unplugged clock spring, light comes right back on.

The tps wiring is good, the connectors for the transmission are clean and good. With the solous hooked up I have correct voltage at tps and sensor is working as it should.

Thoughts? Ideas?



Was thinking is might be a dying ecu or tcu but don't wanna spend the money if I'm overlooking something dumb.

PFA
2onZsU6

2onZRBi
 
Sensor failure and wire harness issues are common, PCM and TCU failure is uncommon. The P0700 is likely a related symptom and not a root cause.

Are you installing genuine Jeep sensors ? Non-Jeep sensors are always suspect. Have you physically and visually inspected the TPS wire harness for chafed/melted wire insulation, damaged wires, and failed wire splices? Are your TPS test results in an approximate range of from .25 volts at minimum throttle opening (idle), to 4.5 volts at WOT wide open throttle?

Code P0122 Jeep

Throttle Position Sensor Circuit Low Input

Read more:
- Possible Causes Faulty throttle position sensor
- Throttle position sensor harness is open or shorted
- Throttle position sensor circuit poor electrical connection

Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.


The TPS is mounted on the throttle body. The TPS is a variable resistor that provides the Powertrain Control Module (PCM) with an input signal (voltage) that represents throttle blade position. The sensor is connected to the throttle blade shaft. As the position of the throttle blade changes, the resistance of the TPS changes. Along with inputs from other sensors, the PCM uses the TPS input to determine current engine operating conditions. In response to engine operating conditions, the PCM will adjust fuel injector pulse width and ignition timing.

The PCM supplies approximately 5 volts to the TPS. The TPS output voltage (input signal to the PCM) represents the throttle blade position. The PCM receives an input signal voltage from the TPS. It is best to use an analog meter (not digital) to see if the transition from idle to WOT is smooth with no dead spots. With your meter set for volts, put the black probe on a good ground like your negative battery terminal. With the key on, engine not running, test with the red probe of your meter (install a paper clip into the back of the plug of the TPS) to see which wire has the 5 volts. This will vary in an approximate range of from .25 volts at minimum throttle opening (idle), to 4.5 volts at WOT wide open throttle.
 
I've gone through 3 bad tps's out of the box in a row. Also have had one go bad from merely driving on the highway in a heavy downpour. I have an analog meter just for testing tps's. It's surprising how often they are the culprit.
 
Yes, OEM Mopar sensors. Wiring for tps is in good shape, so is the connector, no corrosion on connector or pins.

.33v to 4.45v is the range I'm getting with a analog volt meter.
The wiring
 
Be aware of the fact that most volt/ohm meters (under $1k) are not not capable of accurate measurements at such low values. Yes it's hard to find good sensors and bad wiring is the next most common.
 
Be aware of the fact that most volt/ohm meters (under $1k) are not not capable of accurate measurements at such low values. Yes it's hard to find good sensors and bad wiring is the next most common.

I can verify tps voltage with the scanner (snapon stolus), got a nice multimeter that does do low voltage good, and local part store has a sensor (tps) tester that has verified the on on there is good. Also it's the tps off my other jeep.

Update: checked all the wiring, getting ready to ohem it all out for the tps circut when it dethaws inside.
 
A scanner does not measure the voltages, it just reports what the PCM thinks its seeing.
 
Fixed, went to junkyard and got a new to me pcm, flashed vin with my dbr III and 140 miles of no codes. Thanks for all the help everyone.
 
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