P0120
Throttle Position Sensor (TPS) Circuit:
CIRCUIT OPERATION
- A 5-volt power supply is applied on the TPS power terminal (terminal 4) from the ECM (terminal 42)
The ground terminal (terminal 4) is grounded with ECM (terminal 49)
- When the throttle valve shaft is turned from the idle position to the fully opened position, the resistor between the TPS output terminal (terminal 3) and ground terminal will increase according to the rotation.
TECHNICAL DESCRIPTION
- The TPS outputs voltage which corresponds to the throttle valve opening angle.
- The ECM
DTC SET CONDITIONS
Check Conditions
- Two seconds or more have passed since the starting sequence was completed.
Judgement Criteria
- The sensor output voltage remains 2 volts or more for two seconds when engine speed is 1,000 r/min or less, and volumetric efficiency is 60% or less.
or
- TPS output voltage has continued to be 0.2 volt or lower for 2 seconds.
Check Conditions
- Two seconds or more have passed since the staring sequence was completed.
- Engine speed is lower than 3,000 r/min.
- Volumetric efficiency is lower than 30 percent.
Judgement Criteria
- TPS output voltage has continued to be 4.6 volts or higher for 2 seconds.
Check Conditions
- Two seconds or more have passed since the staring sequence was completed.
- Engine speed is higher than 2,000 r/min.
- Volumetric efficiency is higher than 60 percent.
Judgement Criteria
- TPS output voltage has continued to be 0.8 volt or lower for 2 seconds.
TROUBLESHOOTING HINTS
The most likely causes for this code to be set are:
- TPS failed or misadjusted.
- Open or shorted TPS circuit, or loose connector.
- ECM failed.
- PCM failed.
DIAGNOSIS
Required Special Tools:
MB991502: Scan Tool (MUT-II)
CAUTION: To prevent damage to scan tool MB991502, always turn the ignition switch to "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.
STEP 1. Using scan tool MB991502, check data list item 14: Throttle Position Sensor.
1. Connect scan tool MB991502 to the data link connector.
2. Turn the ignition switch to "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 0.535 and 0.735 volts.
- With the throttle valve in the full-open position, voltage should be between 4.5 and 5.5 volts.
4. Turn the ignition switch to "LOCK" (OFF) position.
If the checks above meet the specifications, the malfunction is intermittent.
Refer to How to Use Troubleshooting/Inspection Service Points - How to Cope With Intermittent Malfunction.
If the checks above do not meet the specifications, go to Step 2.
STEP 2. Check the throttle position sensor (TPS)
1. Disconnect TPS connector B-07.
2. Measure resistance between the TPS side connector terminals 1 and 4.
Standard value: 3.5 - 6.5 kohms
3. Measure resistance between the TPS side connector terminals 1 and 3. With test probes in place, 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.
If all checks above meet the specifications, go to Step 3. If any check above does not meet the specifications, replace the TPS. Refer to Throttle Body - Disassembly and Assembly. Then go to Step 7.
STEP 3. Check the circuits at throttle position sensor (TPS) connector B-07.
1. Disconnect connector B-07 and measure at the harness side.
2. Turn the ignition switch to "ON" position.
3. Measure the voltage between terminal 4 and ground.
- Voltage should be between 4.8 and 5.2 volts.
4. Turn the ignition switch to "LOCK" (OFF) position.
5. Check for the continuity between terminal 1 and ground.
- Should be less than 2 ohms .
If all checks above meet the specifications, go to Step 4.
If any check above does not meet the specifications, go to Step 5.
STEP 4. Check harness connector B-07 at the TPS for damage.
If harness connector B-07 is in good condition, go to Step 5.
If harness connector B-07 is damaged, repair or replace it. Refer to Harness Connector Inspection. Then go to Step 7.
STEP 5. Check harness connector C-58, C-62 at the ECM
If harness connector C-58, C-62
If harness connector C-58, C-62
STEP 6. Check the harness wire between throttle position sensor (TPS) connector B-07 and ECM connector C-58, C-62
If the wire between TPS connector B-07 and ECM connector C-58, C-62
Then go to Step 7.
If the wire between TPS connector B-07 and the ECM connector C-58, C-62
STEP 7. Test the OBD-II drive cycle.
1. Carry out a test drive with the drive cycle pattern. Refer to Procedure 6 - Other Monitor.
2. Read the diagnostic trouble code, and confirm that diagnostic trouble code P0120 does not reset.