P0123

DTC P0123: Throttle Position Sensor Circuit High Input

Throttle Position Sensor (TPS) Circuit:

CIRCUIT OPERATION
- A 5-volt power supply is applied on the throttle position sensor power terminal (terminal No.1) from the ECM (terminal No.42). The ground terminal (terminal No.4) is grounded with ECM (terminal No.49).
- When the throttle valve shaft is turned from the idle position to the fully opened position, the resistor between the throttle position sensor output terminal (terminal No.2) and ground terminal will increase according to the rotation.

TECHNICAL DESCRIPTION
- The throttle position sensor outputs voltage which corresponds to the throttle valve opening angle.
- The ECM checks whether the voltage is within a specified range. In addition, it checks that the voltage output does not become too high while the engine is at idle.

DESCRIPTIONS OF MONITOR METHODS
- Throttle position sensor output voltage is out of specified range.

MONITOR EXECUTION
- Continuous

MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)

Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
- Not applicable

Sensor (The sensor below is determined to be normal)
- Not applicable

DTC SET CONDITIONS

Logic Flow Chart:

Logic Flow Chart

Check Conditions
- 2 seconds or more have passed since the engine starting sequence was completed.
- Engine speed is lower than 4,500 r/min.
- Volumetric efficiency is lower than 60 percent.

Judgment Criterion
- TPS output voltage has continued to be 4.8 volts or higher for 2 seconds.

OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 23. OBD-II Drive Cycle Pattern Lists

TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Throttle position sensor failed or incorrectly adjusted.
- Open throttle position sensor circuit, harness damage, or connector damage.
- ECM failed.

DIAGNOSIS

Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991911: Main Harness B

STEP 1. Using scan tool MB991958, check data list item 14: Throttle Position Sensor.

CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.




1. Connect scan tool MB991958 to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. Set scan tool MB991958 to the data reading mode for item 14, Throttle Position Sensor.
- With the throttle valve in the idle position, voltage should be between 0.535 and 0.735 volt.
- With the throttle valve in the full-open position, voltage should be between 4.5 and 5.0 volts.

4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the sensor operating properly?

YES: It can be assumed that this malfunction is intermittent.

NO: Go to Step 2.




STEP 2. Check harness connector B-03 at throttle position sensor for damage.

Q: Is the harness connector in good condition?

YES: Go to Step 3.

NO: Repair or replace it. Then go to Step 8.

STEP 3. Check for continuity at throttle position sensor harness side connector B-03.




1. Disconnect connector B-03 and measure at the harness side.




2. Measure the continuity between terminal No.4 and ground.
- Should be less than 2 Ohms.

Q: Does continuity exist?

YES: Go to Step 6.

NO: Go to Step 4.




STEP 4. Check harness connector C-119 at ECM for damage.

Q: Is the harness connector in good condition?
YES: Go to Step 5.
NO: Repair or replace it. Then go to Step 8.







STEP 5. Check for open circuit and harness damage between throttle position sensor connector B-03 (terminal No.4) and ECM connector C-119 (terminal No.49).

Q: Is the harness wire in good condition?

YES: Replace the ECM. Then go to Step 8.

NO: Repair it. Then go to Step 8.

STEP 6. Check the throttle position sensor.




1. Disconnect connector B-03.




2. Measure the resistance between throttle position sensor side connector terminal No.1 and No.4.

Standard value: 3.5 - 6.5 kOhms

3. Measure resistance between the throttle position sensor side connector terminal No.1 and No.2.
4. Move the throttle valve from the idle position to the full-open position.
- Resistance should change smoothly in proportion to the opening angle of the throttle valve.

Q: Is the measured resistance normal?

YES: Go to Step 7.

NO: Replace the throttle position sensor. Refer to, Throttle Body Assembly - Disassembly and Assembly, Throttle Body. Then go to Step 8.

STEP 7. Using scan tool MB991958, check data list item 14: Throttle Position Sensor.

CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.




1. Connect scan tool MB991958 to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. Set scan tool MB991958 to the data reading mode for item 14, Throttle Position Sensor.
- With the throttle valve in the idle position, voltage should be between 0.535 and 0.735 volt.
- With the throttle valve in the full-open position, voltage should be between 4.5 and 5.0 volts.

4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the sensor operating properly?

YES: It can be assumed that this malfunction is intermittent.

NO: Replace the ECM. Then go to Step 8.

STEP 8. Test the OBD-II drive cycle.

1. Carry out a test drive with the drive cycle pattern. Refer to, Diagnostic Function - OBD-II Drive Cycle - Pattern 23. OBD-II Drive Cycle Pattern Lists
2. Check the diagnostic trouble code (DTC).

Q: Is DTC P0123 set?

YES: Retry the troubleshooting.

NO: The inspection is complete.