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P0122

DTC P0122: Throttle Position Sensor Circuit Low Input

Throttle Position Sensor (TPS) Circuit Part 1:




Throttle Position Sensor (TPS) Circuit Part 2:






CIRCUIT OPERATION
- A 5-volt power supply is applied on the throttle position sensor power terminal (terminal No. 3) from the ECM (terminal No. 81) or PCM (terminal No. 46) .
The ground terminal (terminal No. 2) is grounded with ECM (terminal No. 92) or PCM (terminal No. 57)
.
- When the throttle valve shaft is turned from the idle position to the fully opened position, the resistor between the throttle position sensor out-put terminal (terminal No. 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 or PCM
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
- A short circuit is detected while monitoring the throttle position sensor output.

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 below is determined to be normal)
- Volume airflow sensor

DTC SET CONDITIONS

Logic Flow Chart:




Logic Flow Chart

Check Conditions
- 2 seconds or more have passed since the starting sequence was completed.

Judgement Criteria
- Throttle position sensor output voltage has continued to be 0.2 volt or lower for 2 seconds.

OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function - OBD-II Drive Cycle - Procedure 6 - Other Monitor.
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 or shorted throttle position sensor circuit, 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




STEP 1. Using scan tool or 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 measure between 0.335 and 0.935 volt.
- With the throttle valve in the full-open position, voltage should measure 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 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 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. 3 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 6.

NO: Go to Step 4.







STEP 4. Check harness connector C-115 at ECM or connector C-118 at PCM
for damage.

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. 3) and ECM connector C-115 (terminal No. 81) or PCM connector C-118 (terminal No. 46)
.

Q: Is the harness wire in good condition?

YES: Replace the ECM or PCM. Then go to Step 11.

NO: Repair it. Then go to Step 11.

STEP 6. Check the throttle position sensor.




1. Disconnect connector B-03.




2. Measure the resistance between throttle position sensor side connector terminal No. 2 and No. 3.
Standard value: 2.0 - 4.0 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. Then go to Step 11.







STEP 7. Check harness connector C-115 at ECM or harness connectors C-118, C-116 at PCM
for damage.

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 open circuit and short circuit to ground between throttle position sensor connector B-03 (terminal No. 1) and ECM connector C-115 (terminal No. 84) or PCM connector C-116 (terminal No. 78)
.

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 short circuit to ground between throttle position sensor connector and auto-cruise control-ECU.

Refer to Auto Cruise Control System - Diagnostic Trouble Code Chart.
Diagnostic Trouble Code Descriptions

Q: Is the harness wire in good condition?

YES: Go to Step 10.

NO: Repair it. Then go to Step 11.




STEP 10. 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 measure between 0.335 and 0.935 volt.
- With the throttle valve in the full-open position, voltage should measure 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 11.

STEP 11. 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 - Procedure 6 - Other Monitor. OBD-II Drive Cycle Pattern Lists
2. Check the diagnostic trouble code (DTC).

Q: Is DTC P0122 set?

YES: Retry the troubleshooting.

NO: The inspection is complete.