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DTC P1234: Throttle
Position Sensor (Sub) Plausibility
TECHNICAL DESCRIPTION
Compare the actual measurement of volumetric efficiency by a mass airflow sensor signal with
volumetric efficiency estimated from a throttle position sensor (sub) signal.
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)
Sensor (The sensor below is determined to be normal)
DTC SET CONDITIONS
Logic Flow Chart
Check Conditions
- The difference between the actual volumetric efficiency and the volumetric efficiency estimated
by the throttle position sensor (sub) is 0 percent or more. Or, the volumetric efficiency is 60
percent or less.
- The engine speed is between 750 and 3,000 r/min. Or, the throttle position sensor (main)
output voltage is 3 volts or less.
Judgment Criterion
- For 0.4 second, the difference between the actual volumetric efficiency and the volumetric
efficiency estimated by the throttle position sensor (sub) is 33 percent or more.
OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function - OBD-II Drive Cycle Pattern 17 
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TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Throttle position sensor (sub) system failed.
- Intake system vacuum leak.
- There is some trash around mass airflow sensor.
- ECM failed.
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Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991910: Main Harness A
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STEP 1. Using scan tool MB991958, read the diagnostic
trouble code (DTC).
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| 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.
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(1)Connect scan tool MB991958 to the data link connector.
(2)Turn the ignition switch to the "ON" position.
(3)Read the DTC.
(4)Turn the ignition switch to the "LOCK" (OFF) position.
Q.
Is the diagnostic trouble code other than P1234 set?
 Refer to, Diagnostic Trouble Code Chart .
 Go to Step 2.
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STEP 2. Using scan tool MB991958, check data list item 15: Throttle
Position Sensor (sub).
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(1)Turn the ignition switch to the "ON" position.
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(2)Detach the intake air hose at the throttle body.
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(3)Disconnect the connector of the throttle position sensor.
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(4)Use test harness special tool (MB991658) to connect only terminals No. 3, No. 4,
No. 5, and No. 6.
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(5)Set scan tool MB991958 to the data reading mode for item 15, Throttle Position
Sensor (sub).
- Output voltage should be 4.0 volts or more when the throttle valve is fully
closed with your finger.
- Output voltage should be 1.0 volt or less when the throttle valve is fully open
with your finger.
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(6)Turn the ignition switch to the "LOCK" (OFF) position.
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Q.
Is the sensor operating properly?
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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 .
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Go to Step 3.
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STEP 3. Check for intake system vacuum leak.
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Q.
Are there any abnormalities?
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Repair it. Then go to Step 6.
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Go to Step 4.
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STEP 4. Check for foreign matter being around the mass airflow sensor.
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Q.
Are there any foreign matter?
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Repair it. Then go to Step 6.
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Go to Step 5.
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STEP 5. Check the trouble symptoms.
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(1)Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II
Drive Cycle Pattern 17 .
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(2)Check the diagnostic trouble code (DTC).
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Replace the ECM. When the ECM is replaced, register the ID code. Refer to GROUP
42B, ID Code Registration Necessity Judgment Table <Vehicles with KOS> or
GROUP 42C, ID Codes Registration Judgment Table <Vehicles with WCM> .
The go to Step 6.
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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 .
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STEP 6. Test the OBD-II drive cycle.
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(1)Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II
Drive Cycle Pattern 17 .
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(2)Check the diagnostic trouble code (DTC).
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Retry the troubleshooting.
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The inspection is complete.
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