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DTC P0657: Throttle Actuator Control Motor Relay Circuit Malfunction
 
 
 
 
CIRCUIT OPERATION
  • 12V starter battery positive voltage is applied to the throttle actuator control motor relay terminal.
  • 12V starter battery positive voltage is applied to the throttle actuator control motor relay terminal from the MFI relay.
  • 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, 12V starter battery positive voltage is supplied by the throttle actuator control motor relay to the ECM terminal RSB.
 
 
TECHNICAL DESCRIPTION
  • When the power supply mode of the electric motor 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 set 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
  • 12V starter battery positive voltage is higher than 8.3 volts.
Judgment Criterion
  • The power line voltage of the electronic controlled throttle valve system should be 6.0 volts or lower for 0.35 second.
 
 
FAIL-SAFE AND BACKUP FUNCTION
  • Throttle opening degree position is in default position.
 
 
OBD-II DRIVE CYCLE PATTERN
  • Refer to Diagnosis Function - OBD-II Drive Cycle - Pattern 1 .
 
 
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
STEP 1. Check the throttle actuator control motor relay.
Refer to Throttle Actuator Control Motor Relay Continuity Check .
Is the measured resistance 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 12V starter battery power supply line and ground.
  • Voltage should be 12V starter battery positive voltage.
Is 12V starter battery positive voltage (approximately 12 volts) present?
Go to Step 3.
Repair or replace the connector(s), or check and repair the harness of short to ground and open circuit in 12V starter battery power supply line between 12V starter 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 on the power supply mode of the electric motor switch.
(3) Measure the voltage between terminal coil power supply line and ground.
  • Voltage should be 12V starter battery positive voltage.
(4) Turn off the power supply mode of the electric motor switch.
Is 12V starter battery positive voltage (approximately 12 volts) present?
Go to Step 4.
Repair or replace the connector(s), or check and repair the harness of short to ground and open circuit 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 ECM connector and measure at the harness side.
(2) Short-circuit the terminal C/R of the ECM harness connector to the ground.
(3) Measure the voltage between terminal C/RL and ground.
  • Voltage should be 12V starter battery positive voltage.
Is 12V starter battery positive voltage (approximately 12 volts) present?
Go to Step 5.
Repair or replace the connector(s), or check and repair the harness of short to ground and open circuit 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.
(1) Disconnect the ECM connector and measure at the harness side.
(2) Short-circuit the terminals C/R and C/RL of the ECM harness connector to the ground.
(3) Measure the voltage between terminal RSB and ground.
  • Voltage should be 12V starter battery positive voltage.
Is 12V starter battery positive voltage (approximately 12 volts) present?
Go to Step 8.
Go to Step 6.
 
STEP 6. Check of short to ground and open circuit 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 the connector(s) or wiring harness. 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 damage 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 12V starter battery power supply line between 12V starter battery and throttle actuator control motor relay connector.
Is the harness wire in good condition?
Go to Step 9.
Repair the connector(s) or wiring harness. 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 the connector(s) or wiring harness. Then go to Step 11.
 
STEP 10. Check the trouble symptoms.
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn off the power supply mode of the electric motor switch before connecting or disconnecting scan tool (M.U.T.-IIISE).
(1) Connect scan tool (M.U.T.-IIISE). Refer to HOW TO CONNECT THE SCAN TOOL (M.U.T.-IIISE) .
(2) Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 1 .
(3) Check the diagnostic trouble code (DTC).
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. Test the OBD-II drive cycle.
cautionTo prevent damage to scan tool (M.U.T.-IIISE), always turn off the power supply mode of the electric motor switch before connecting or disconnecting scan tool (M.U.T.-IIISE).
(1) Connect scan tool (M.U.T.-IIISE). Refer to HOW TO CONNECT THE SCAN TOOL (M.U.T.-IIISE) .
(2) Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 1 .
(3) Check the diagnostic trouble code (DTC).
Is DTC P0657 set?
Retry the troubleshooting.
The inspection is complete.