Code No. P0657: Throttle Valve Control Servo Relay Circuit Malfunction
OPERATION
- Battery voltage is applied to the throttle valve control servo relay.
- Battery voltage is applied to the throttle valve control servo relay from the engine control relay.
- Engine-ECU connector terminal C/RL applies current to the throttle valve control servo relay by turning ON the power transistor in the unit in order to turn the relay ON.
- When the throttle valve control servo relay turns ON, battery voltage is supplied by the throttle valve control servo relay to the engine-ECU connector terminal RSB.
FUNCTION
- When the ignition switch "ON" signal is input into the engine-ECU, the engine-ECU turns ON the throttle valve control servo.
TROUBLE JUDGEMENT
Check Condition
- Battery positive voltage is more than 8.3 V.
Judgement Criterion
- The power line voltage of the electronic controlled throttle system is less than 6.0 V.
FAIL-SAFE AND BACKUP FUNCTION
- Throttle opening degree position is in default position.
PROBABLE CAUSES
- Failed throttle valve control servo relay
- Open/short circuit or harness damage in throttle valve control servo relay circuit or loose connector contact
- Failed engine-ECU
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STEP 1. Check throttle valve control servo relay itself.
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- Throttle valve control servo relay check (Refer to
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Q.
Is the check result normal?
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 Go to Step 2.
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 Replace the throttle valve control servo relay.
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STEP 2. Voltage measurement at throttle valve control servo relay connector (battery side power supply line).
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(1)Remove the relay, and measure at the relay box side.
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(2)Check the voltage between the throttle valve control servo relay connector (battery side power supply line) and body earth.
OK: System voltage
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Q.
Is the check result normal?
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Go to Step 3.
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Repair or replace the connector(s), or check and repair the harness of short to earth and open circuit in power supply line between battery and throttle valve control servo relay connector.
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STEP 3. Voltage measurement at throttle valve control servo relay connector (engine control relay side power supply line).
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(1)Remove the relay, and measure at the relay box side.
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(3)Check the voltage between the throttle valve control servo relay connector (engine control relay side power supply line) and body earth.
OK: System voltage
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Q.
Is the check result normal?
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Go to Step 4.
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Repair or replace the connector(s), or check and repair the harness of short to earth and open circuit in power supply line between engine control relay connector and throttle valve control servo relay connector.
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STEP 4. Voltage measurement at engine-ECU connector (C/RL terminal).
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(1)Disconnect the connector, and measure at the wiring harness side.
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(2)Short-circuit engine-ECU connector (C/R terminal) to the body earth.
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(3)Check the voltage between the engine-ECU connector (C/RL terminal) and body earth.
OK: System voltage
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Q.
Is the check result normal?
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Go to Step 5.
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Repair or replace the connector(s), or check and repair the harness of short to earth and open circuit in C/RL line between throttle valve control servo relay connector and engine-ECU connector.
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STEP 5. Voltage measurement at engine-ECU connector (RSB terminal).
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(1)Disconnect the connector, and measure at the wiring harness side.
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(2)Short-circuit engine-ECU connector (C/R and C/RL terminal) to the body earth.
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(3)Check the voltage between the engine-ECU connector (RSB terminal) and body earth.
OK: System voltage
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Q.
Is the check result normal?
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Go to Step 6.
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Repair or replace the connector(s), or check and repair the harness of short to earth and open circuit in RSB line between throttle valve control servo relay connector and engine-ECU connector.
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STEP 6. Check of harness damage in power supply line between battery and throttle valve control servo relay connector.
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Q.
Is the check result normal?
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Go to Step 7.
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Repair the connector(s) or wiring harness.
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STEP 7. Check of harness damage in power supply line between engine control relay connector and throttle valve control servo relay connector.
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Q.
Is the check result normal?
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Go to Step 8.
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Repair the connector(s) or wiring harness.
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STEP 8. Check of harness damage in C/RL line between throttle valve control servo relay connector and engine-ECU connector.
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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 harness damage in RSB line between throttle valve control servo relay connector and engine-ECU connector.
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Q.
Is the check result normal?
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Go to Step 10.
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Repair the connector(s) or wiring harness.
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STEP 10. M.U.T.-III diagnosis code
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- Reconfirmation of diagnosis code.
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Q.
Is diagnosis code set?
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Replace the engine-ECU.
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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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