P0122
DTC P0122: Throttle Position Sensor (main) Circuit Low InputThrottle Position Sensor (main) Circuit:
CIRCUIT OPERATION
- A 5-volt power supply is applied on the throttle position sensor (main) power terminal (terminal No. 5) from the ECM
The ground terminal (terminal No. 3) is grounded with ECM
- When the throttle valve shaft is turned from the idle position to the fully opened position, the resistance between the throttle position sensor (main) output terminal (terminal No. 4) and ground terminal will increase according to the rotation.
TECHNICAL DESCRIPTION
- The throttle position sensor (main) outputs voltage which corresponds to the throttle valve opening angle.
- The ECM
DESCRIPTIONS OF MONITOR METHODS
Throttle position sensor (main) 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)
- Not applicable
Sensor (The sensor is determined to be normal)
- Not applicable
DTC SET CONDITIONS
Logic Flow Chart:
Logic Flow Chart
Check Condition
- Ignition switch "ON" position.
Judgement Criteria
- Throttle position sensor (main) output voltage should be 0.35 volt or less for 0.5 second.
OBD-II DRIVE CYCLE PATTERN
None.
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Throttle position sensor failed.
- Open or shorted throttle position sensor (main) circuit, harness damage, or connector damage.
- ECM failed.
- PCM failed.
DIAGNOSIS
Required Special Tools:
- MB991958: Scan tool (MUT-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991911: Main Harness B
- MB991658: Test Harness
STEP 1. Using scan tool MB991958, check data list item 79: Throttle Position Sensor (main).
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. Detach the intake air hose at the throttle body.
4. Disconnect the connector of the throttle position sensor.
5. Use test harness special tool (MB991658) to connect only terminals No. 3, No. 4, No. 5, and No. 6.
6. Set scan tool MB991958 to the data reading mode for item 79, Throttle Position Sensor (main).
- Output voltage should be between 0.3 and 0.7 volt when the throttle valve is fully closed with your finger.
- Output voltage should be between 4.0 volts or more when the throttle valve is fully open with your finger.
7. 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 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. Refer to Harness Connector Inspection. Then go to Step 11.
STEP 3. Measure the sensor supply voltage at throttle position sensor harness side connector B-03.
1. Disconnect the connector B-03 and measure at the harness side.
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between terminal No. 5 and ground.
- Voltage should be between 4.8 and 5.2 volts.
4. Turn the ignition switch to the "LOCK"(OFF) position.
Q: Is the measured voltage between 4.8 and 5.2 volts?
YES: Go to Step 7.
NO: Go to Step 4.
STEP 4. Check harness connector C-139 at ECM
Q: Is the harness connector in good condition?
YES: Go to Step 5.
NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 11.
STEP 5. Check for open circuit and short circuit to ground between throttle position sensor connector B-03 (terminal No. 5) and ECM connector C-139
Q: Is the harness wire in good condition?
YES: Go to Step 6.
NO: Repair it. Then go to Step 11.
STEP 6. Using scan tool MB991958, check data list item 79: Throttle Position Sensor (main).
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. Detach the intake air hose at the throttle body.
4. Disconnect the connector of the throttle position sensor.
5. Use test harness special tool (MB991658) to connect only terminals No. 3, No. 4, No. 5, and No. 6.
6. Set scan tool MB991958 to the data reading mode for item 79, Throttle Position Sensor (main).
- Output voltage should be between 0.3 and 0.7 volt when the throttle valve is fully closed with your finger.
- Output voltage should be 4.0 volts or more when the throttle valve is fully open with your finger.
7. 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 11.
STEP 7. Check harness connector C-139 at ECM
Q: Is the harness connector in good condition?
YES: Go to Step 8.
NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 11.
STEP 8. Check for harness damage between throttle position sensor connector B-03 (terminal No. 5) and ECM connector C-139
Q: Is the harness wire in good condition?
YES: Go to Step 9.
NO: Repair it. Then go to Step 11.
STEP 9. Check for open circuit, short circuit to ground and harness damage between throttle position sensor connector B-03 (terminal No. 4) and ECM connector C-139
Q: Is the harness wire in good condition?
YES: Go to Step 10.
NO: Repair it. Then go to Step 11.
STEP10. Replace the throttle body assembly.
1. Replace the throttle body assembly.
2. Turn the ignition switch to the "ON" position.
3. After the DTC has been deleted, read the DTC again.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is DTC P0122 set?
YES: Replace the ECM or PCM. Then go to Step 11.
NO: The inspection is complete.
STEP 11. Using scan tool MB991958, read the diagnostic trouble code (DTC).
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. After the DTC has been deleted, read the DTC again.
4. Turn the ignition switch to the "LOCK"(OFF) position.
Q: Is DTC P0122 set?
YES: Retry the troubleshooting.
NO: The inspection is complete.