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DTC P0657: Throttle Actuator Control Motor Relay Circuit Malfunction
 
 
 
 
CIRCUIT OPERATION
  • Battery positive voltage is applied to the throttle actuator control motor relay terminal.
  • Battery positive voltage is applied to the throttle actuator control motor relay terminal from the MFI relay terminal.
  • ECM terminal C/RL applies current to the throttle actuator control motor relay coil by turning ON the power transistor in the unit in order to turn the relay ON.
  • When the throttle actuator control motor relay turns ON, battery positive voltage is supplied by the throttle actuator control motor relay to the ECM terminal RSB.
 
 
TECHNICAL DESCRIPTION
  • When the ignition switch ON signal is input into the ECM, the ECM turns ON the throttle actuator control motor relay.
 
 
DESCRIPTIONS OF MONITOR METHODS
  • Throttle actuator control motor relay circuit voltage is smaller than the specified value.
 
 
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
Check Condition
  • Battery positive voltage is more than 8.3 volts.
Judgment Criterion
  • The power line voltage of the electronic-controlled throttle valve system is less than 6.0 volts for 0.35 second.
 
 
FAIL-SAFE AND BACKUP FUNCTION
  • Throttle opening degree position is in default position.
 
 
OBD-II DRIVE CYCLE PATTERN
  • None.
 
 
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
  • Throttle actuator control motor relay failed.
  • Open or shorted throttle actuator control motor relay circuit, harness damage or 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)
STEP 1. Check the throttle actuator control motor relay.
Refer to Throttle Actuator Control Motor Relay Continuity Check .
Is the throttle actuator control motor relay normal?
Go to Step 2.
Replace the throttle actuator control motor relay. Then go to Step 11.
 
STEP 2. Measure the power supply voltage at throttle actuator control motor relay harness side connector.
(1) Disconnect the throttle actuator control motor relay connector and measure at the harness side.
(2) Measure the voltage between terminal battery line and ground.
  • Voltage should be battery positive voltage.
Is battery positive voltage (approximately 12 volts) present?
Go to Step 3.
Repair or replace the connector(s), or check and repair the harness of open circuit and short to ground in battery line between battery and throttle actuator control motor relay connector. Then go to Step 11.
 
STEP 3. Measure the power supply voltage at throttle actuator control motor relay harness side connector.
(1) Disconnect the throttle actuator control motor relay connector and measure at the harness side.
(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal coil power supply line and ground.
  • Voltage should be battery positive voltage.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is battery positive voltage (approximately 12 volts) present?
Go to Step 4.
Repair or replace the connector(s), or check and repair the harness of open circuit and short to ground in coil power supply line between MFI relay connector and throttle actuator control motor relay connector. Then go to Step 11.
 
STEP 4. Measure the power supply voltage at ECM harness side connector.
(1) Disconnect the connector and measure at the harness side.
(2) Short-circuit the terminal C/R line of the ECM harness connector to the ground.
(3) Measure the voltage between terminal C/RL line and ground.
  • Voltage should be battery positive voltage.
Is battery positive voltage (approximately 12 volts) present?
Go to Step 5.
Repair or replace the connector(s), or check and repair the harness of open circuit and short to ground in C/RL line between throttle actuator control motor relay connector and ECM connector. Then go to Step 11.
 
STEP 5. Measure the power supply voltage at ECM harness side connector B-27.
(1) Disconnect the connector and measure at the harness side.
(2) Short-circuit the terminals C/R line and C/RL line of the ECM harness connector to the ground.
(3) Measure the voltage between terminal RSB line and ground.
  • Voltage should be battery positive voltage.
Is battery positive voltage (approximately 12 volts) present?
Go to Step 8.
Go to Step 6.
 
STEP 6. Check of open circuit and short circuit to ground in RSB line between throttle actuator control motor relay connector and ECM connector.
Is the harness wire in good condition?
Go to Step 7.
Repair it. Then go to Step 11.
 
STEP 7. Check of harness damage in coil power supply line between MFI relay connector and throttle actuator control motor relay connector.
Is the harness wire in good condition?
Repair or replace the connector(s), or check and repair the harness of open circuit in C/RL line between throttle actuator control motor relay connector and ECM connector. Then go to Step 11.
Repair the connector(s) or wiring harness. Then go to Step 11.
 
STEP 8. Check of harness damage in battery line between battery and throttle actuator control motor relay connector.
Is the harness wire in good condition?
Go to Step 9.
Repair it. Then go to Step 11.
 
STEP 9. Check of harness damage in RSB line between throttle actuator control motor relay connector and ECM connector.
Is the harness wire in good condition?
Go to Step 10.
Repair it. Then go to Step 11.
 
STEP 10. Using scan tool (M.U.T.-III), read the diagnostic trouble code (DTC).
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). Refer to HOW TO CONNECT THE SCAN TOOL (M.U.T.-III) .
(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 P0657 set?
Replace the ECM (Refer to, Removal and Installation ). Then go to Step 11.
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 .
 
STEP 11. Using scan tool (M.U.T.-III), read the diagnostic trouble code (DTC).
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). Refer to HOW TO CONNECT THE SCAN TOOL (M.U.T.-III) .
(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 P0657 set?
Retry the troubleshooting.
The inspection is complete.