P0123
Throttle Position Sensor (TPS) Circuit:
CIRCUIT OPERATION
- A 5-volt power supply is applied on the throttle position sensor power terminal (terminal 3) from the ECM (terminal 81)
The ground terminal (terminal 2) is grounded with ECM (terminal 92)
- 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 1) 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
DTC SET CONDITIONS
Check Conditions
- 2 seconds or more have passed since the starting sequence was completed.
- Engine speed is lower than 1,000 r/min.
- Volumetric efficiency is lower than 60 percent.
Judgement Criteria
- Throttle position sensor output voltage has continued to be 2 volts or higher for 2 seconds.
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Throttle position sensor failed or maladjusted.
- Open or shorted throttle position sensor circuit, or loose connector
- ECM failed.
- PCM failed.
DIAGNOSIS
Required Special Tools
- MB991502: Scan Tool (MUT-II)
STEP 1. Using scan tool MB991502, check data list item 14: Throttle Position Sensor.
CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.
1. Connect scan tool MB991502 to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. Set scan tool MB991502 to the data reading mode for item 14, Throttle Position Sensor
- With the throttle valve in the idle position, voltage should be between 0.335 and 0.935 volt.
- With the throttle valve in the full-open position, voltage should be between 4.39 and 5.29 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. Refer to How to Use Troubleshooting/Inspection Service Points.
NO: Go to Step 2.
STEP 2. Check connector B-03 at throttle position sensor for damage.
Q: Is the connector in good condition?
YES: Go to Step 3.
NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 8.
STEP 3. Check the continuity at throttle position sensor harness side connector B-03.
1. Disconnect the connector B-03 and measure at the harness side.
2. Measure the continuity between terminal 2 and ground.
- Should be less than 2 ohm.
Q: Is the continuity normal?
YES: Go to Step 6.
NO: Go to Step 4.
STEP 4. Check connector C-115 at ECM
Q: Is the connector in good condition?
YES: Go to Step 5.
NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 8.
STEP 5. Check for open circuit and harness damage between throttle position sensor connector B-03 terminal 2 and ECM connector C-115 terminal 92
Q: Is the harness wire in good condition?
YES: Replace the ECM or PCM. Then go to Step 8.
NO: Repair it. Then go to Step 8.
STEP 6. Check the throttle position sensor.
1. Disconnect the connector B-03.
2. Measure the resistance between throttle position sensor side connector terminal 2 and 3.
Standard value: 2.0 - 4.0 kohm
3. Measure resistance between the throttle position sensor side connector terminal 1 and 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 resistance normal?
YES: Go to Step 7.
NO: Replace the throttle position sensor. Refer to Throttle Body. Then go to Step 8.
STEP 7. Using scan tool MB991502, check data list item 14: Throttle Position Sensor.
CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.
1. Connect scan tool MB991502 to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. Set scan tool MB991502 to the data reading mode for item 14, Throttle Position Sensor.
- With the throttle valve in the idle position, voltage should be between 0.335 and 0.935 volt.
- With the throttle valve in the full-open position, voltage should be between 4.39 and 5.29 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. Refer to How to Use Troubleshooting/Inspection Service Points.
NO: Replace the ECM or PCM. 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, Procedure 6- Other Monitor.
2. Check the diagnostic trouble code (DTC).
Q: Is the DTC P0123 output?
YES: Retry the troubleshooting.
NO: The inspection is complete.