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DTC P0123: Throttle Position Sensor (main) Circuit High Input
 
 
 
 
CIRCUIT OPERATION
  • A 5-volt power supply is applied on the throttle position sensor (main) power terminal from the ECM terminal TPS5.
  • A voltage that is according to the throttle opening angle is sent to the ECM terminal TPSM from the throttle position sensor (main) output terminal.
  • The ground terminal is grounded with ECM terminal TPSE.
 
 
TECHNICAL DESCRIPTION
  • The throttle position sensor (main) outputs voltage which corresponds to the throttle valve opening angle.
  • The ECM checks whether the voltage is within a specified range.
 
 
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 below)
  • Not applicable
Sensor (The sensor below is determined to be normal)
  • Not applicable
 
 
DTC SET CONDITIONS
Logic Flow Chart
 
 
Check Condition
  • Ignition switch is "ON" position.
Judgment Criterion
  • Throttle position sensor (main) output voltage should be 4.8 volts or more for 0.3 second.
 
 
FAIL-SAFE AND BACKUP FUNCTION
  • Throttle opening degree is restricted.
  • Throttle opening degree position is in default position if throttle position sensor (sub) fails.
 
 
OBD-II DRIVE CYCLE PATTERN
  • None.
 
 
TROUBLESHOOTING HINTS (The most likely causes for this code to be stored are: )
  • Throttle position sensor failed.
  • Harness damage
  • Connector damage
  • ECM failed.

 
 
DIAGNOSIS
Required Special Tools:
  • MB992744: Vehicle Communication Interface-Lite (V.C.I.-Lite)
  • MB992745: V.C.I.-Lite Main Harness A
  • MB992747: V.C.I.-Lite USB Cable Short
  • MB992748: V.C.I.-Lite USB Cable Long
  • MB991958: Scan Tool (M.U.T.-III Sub Assembly)
    • MB991824: Vehicles Communication Interface (V.C.I.)
    • MB991827: M.U.T.-III USB Cable
    • MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)
  • MB991658: Test Harness
STEP 1. Using scan tool (M.U.T.-III), check data list item 13: Throttle Position Sensor (main).
cautionTo prevent damage to scan tool (M.U.T.-III), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-III).
(1) Connect scan tool (M.U.T.-III) to the data link connector.
(2) Detach the intake air hose at the throttle body.
(3) Disconnect the connector of the throttle body assembly.
(4) Use test harness special tool (MB991658) to connect only terminals TPSE, TPSM, TPS5 and TPSS line.
(5) Turn the ignition switch to the "ON" position.
(6) Set scan tool (M.U.T.-III) to the data reading mode for item 13, 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.
Is the sensor operating properly?
It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions .
Go to Step 2.
 
STEP 2. Measure the sensor supply voltage at throttle position sensor harness side connector.
(1) Disconnect the throttle body assembly connector 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 4.9 and 5.1 volts.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is the measured voltage between 4.9 and 5.1 volts?
Go to Step 4.
Go to Step 3.
 
STEP 3. Check of short to ground and open circuit in TPS5 line between throttle body assembly connector and ECM connector.
Is the harness wire in good condition?
Go to Step 6.
Repair the connector(s) or wiring harness. Then go to Step 10.
 
STEP 4. Check the continuity at throttle position sensor harness side connector.
(1) Disconnect the throttle body assembly connector and measure at the harness side.
(2) Measure the continuity between terminal TPSE line and ground
  • Continuity (2 ohms or less)
Does continuity exist?
Go to Step 7.
Go to Step 5.
 
STEP 5. Check of open circuit and harness damage in TPSE line between throttle body assembly connector and ECM connector.
Is the harness wire in good condition?
Go to Step 6.
Repair the connector(s) or wiring harness. Then go to Step 10.
 
STEP 6. Using scan tool (M.U.T.-III), check data list item 13: Throttle Position Sensor (main).
(1) Detach the intake air hose at the throttle body.
(2) Disconnect the connector of the throttle body assembly.
(3) Use test harness special tool (MB991658) to connect only terminals TPSE, TPSM, TPS5 and TPSS line.
(4) Turn the ignition switch to the "ON" position.
(5) Set scan tool (M.U.T.-III) to the data reading mode for item 13, 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.
(6) Turn the ignition switch to the "LOCK" (OFF) position.
Is the sensor operating properly?
It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions .
Replace the ECM (Refer to Removal and Installation ). Then go to Step 10.
 
STEP 7. Check of harness damage in TPS5 line between throttle body assembly connector and ECM connector.
Is the harness wire in good condition?
Go to Step 8.
Repair the connector(s) or wiring harness. Then go to Step 10.
 
STEP 8. Check of open circuit and harness damage in TPSM line between throttle body assembly connector and ECM connector.
Is the harness wire in good condition?
Go to Step 9.
Repair the connector(s) or wiring harness. Then go to Step 10.
 
STEP 9. 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.
Is DTC P0123 stored?
Replace the ECM (Refer to Removal and Installation ). Then go to Step 10.
The inspection is complete.
 
STEP 10. Using scan tool (M.U.T.-III), read the diagnostic trouble code (DTC).
(1) Turn the ignition switch to the "ON" position.
(2) After the DTC has been deleted, read the DTC again.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Is DTC P0123 stored?
Retry the troubleshooting.
The inspection is complete.