Code No. P2127: Accelerator Pedal Position Sensor (sub) Circuit Low Input
OPERATION
- A power voltage of 5 V is applied to the accelerator pedal position sensor connector terminal from the engine-ECU connector terminal AP5.
- The power voltage is earthed to the engine-ECU connector terminal APE from the accelerator pedal position sensor connector terminal.
- The sensor signal is inputted to the engine-ECU connector terminal APSS from the accelerator pedal position sensor output terminal.
FUNCTION
- The accelerator pedal position sensor converts the opening degree of the accelerator pedal into the voltage signal to input it to the engine ECU.
- The engine ECU uses this signal to determine the amount of basic fuel injection.
TROUBLE JUDGEMENT
Check Conditions
- Ignition switch is in "ON" position
- Accelerator pedal position sensor (main) is normal
Judgement Criterion
- Accelerator pedal position sensor (sub) output voltage is lower than 0.125 V.
FAIL-SAFE AND BACKUP FUNCTION
- The amount of depression of the accelerator pedal is detected, using the accelerator pedal position sensor (main) signal, which is calculated by taking half of the normal value.
PROBABLE CAUSES
- Failed accelerator pedal position sensor
- Open/short circuit or harness damage in accelerator pedal position sensor circuit or loose connector contact
- Failed engine-ECU
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STEP 1. M.U.T.-III data list
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- Refer to Data List Reference Table
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- Item 10: Accelerator pedal position sensor (sub)
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Q.
Is the check result normal?
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 Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions).
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 Go to Step 2.
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STEP 2. Voltage measurement at accelerator pedal position sensor (AP5 line)
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(1)Disconnect the connector, and measure at the wiring harness side.
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(3)Check the voltage between the accelerator pedal position connector (AP5 line) and body earth.
OK: 4.9 - 5.1 V
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Q.
Is the check result normal?
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Go to Step 5.
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Go to Step 3.
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STEP 3. Check of open circuit and short to earth in AP5 line between engine-ECU connector and accelerator pedal position sensor connector.
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Q.
Is the check result normal?
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Go to Step 4.
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Repair the connector(s) or wiring harness.
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STEP 4. M.U.T.-III data list
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- Refer to Data List Reference Table .
- Item 10: Accelerator pedal position sensor (sub)
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Q.
Is the check result normal?
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Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions).
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Replace the engine-ECU.
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STEP 5. Resistance measurement at accelerator pedal position sensor connector (APE line).
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(1)Disconnect the connector, and measure at the wiring harness side.
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(2)Check the voltage between the accelerator pedal position sensor connector (APE line) and body earth.
OK: Continuity (2 Ω or less)
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Q.
Is the check result normal?
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Go to Step 7.
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Go to Step 6.
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STEP 6. Check of damage in APE line between accelerator pedal position sensor connector and engine-ECU connector.
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- Check earthing line for damage.
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Q.
Is the check result normal?
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Go to Step 4.
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Repair the connector(s) or wiring harness.
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STEP 7. Voltage measurement at accelerator pedal position sensor connector (APSS line).
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(1)Use special tool test harness (MB991658) to connect connector, and measure at pick-up harness.
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(3)Check the voltage between the accelerator pedal position sensor connector (APSS line) and body earth.
OK: 0.2 - 0.8 V
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Q.
Is the check result normal?
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Go to Step 10.
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Go to Step 8.
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STEP 8. Check of short to earth in APSS line between engine-ECU connector and accelerator pedal position sensor.
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Q.
Is the check result normal?
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Go to Step 9.
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Repair the connector(s) or wiring harness.
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STEP 9. Check of damage in AP5 line between engine-ECU connector and accelerator pedal position sensor connector.
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Q.
Is the check result normal?
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Replace the accelerator pedal assembly.
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Repair the connector(s) or wiring harness.
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STEP 10. Check of open circuit and damage in APSS line between accelerator pedal position sensor connector and engine-ECU connector.
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Q.
Is the check result normal?
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Go to Step 4.
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Repair the connector(s) or wiring harness.
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