P0123

DTC P0123:

Throttle Position (TP) Sensor Wiring Schematic:

CIRCUIT DESCRIPTION
The Throttle Position (TP) sensor provides a voltage signal that changes relative to throttle blade angle. Signal voltage will vary from 0.2 - 0.74 volts at idle to about 5 volts at Wide Open Throttle (WOT).

The TP sensor signal is one of the most important inputs used by the Powertrain Control Module (PCM) for fuel control and for most of the PCM control outputs.

DIAGNOSTIC TROUBLE CODE (DTC) P0123 WILL SET WHEN
^ TP sensor voltage is greater than 4.8 volts at any time.
OR
^ Engine is running and air flow is less than 17 gm/sec.

^ TP sensor signal voltage is greater than 1.06 volts.
^ DTC P0101 not present.
^ RPM greater than 600 RPM.
^ All conditions met for 5 seconds.

ACTION TAKEN (PCM WILL DEFAULT TO)
If a DTC P0123 is set, the Tech 1 scan tool will continue to display the actual throttle sensor voltage. But ignore TP signal and read mass air flow value for other PCM controlled functions, the PCM will not allow cruise control, 4th gear or Torque Converter Clutch (TCC) operation, 1st, 2nd, and 3rd allowed. The Malfunction Indicator Lamp (MIL) (Service Engine Soon) will be illuminated.

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.

1. With closed throttle, ignition "ON" or at idle, voltage at "BB10" should be 0.2 - 0.74 volts.
2. With the TP sensor disconnected, the TP sensor voltage should go low and a DTC P0122 will set. This test verifies that the PCM and wiring are OK.
3. Probing CKT 452 with a test light checks the sensor ground circuit. A faulty sensor ground circuit will cause a DTC P0123.

DIAGNOSTIC AIDS
The Tech 1 displays throttle position in volts. With closed throttle, ignition "ON" or at idle, voltage should be 0.2 - 0.74 volt. If not, refer to Throttle Position Sensor, Service and Repair for replacement procedures.

An open in sensor ground CKT 452 may result in DTCs P0112, P0712, P0117 and P0123. Refer to "Intermittents," under Diagnosis By Symptom. - Intermittent Malfunctions

Check For:

Poor Connection or Damaged Harness
Inspect PCM harness connectors for backed out terminal "BB10" or "BA8", improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection, and damaged harness.

Intermittent Test
Monitor TP sensor voltage on Tech 1 while moving related connectors and wiring harness. If the failure is induced, the display will change. This may help to isolate the location of the malfunction.

TP sensor Scaling
Observe TP sensor voltage display while depressing accelerator pedal with engine stopped and ignition "ON." Display should vary from closed throttle TP sensor voltage when throttle is closed (0.2 - 0.74 volt) to over 4.0 volts when throttle is held at Wide Open Throttle (WOT) position.