Code No. P0620: Alternator Control Circuit


OPERATION



  • When the ignition switch is turned ON, the current should be supplied from the engine-ECU (terminal No. 7) to the alternator (terminal No. 3). When the engine starts under those conditions, the alternator should generate currents.The generated voltage is applied to the engine-ECU (terminal No. 7) from the alternator (terminal No. 3).This allows the engine-ECU to detect that the electrical generation begins.
  • The engine-ECU (terminal No. 121) controls the alternator output voltage by turning the power transistor in the unit ON/OFF according to the electrical load.

FUNCTION



  • The engine-ECU compares the battery voltage with the voltage generated from the alternator to check whether the electrical generation is normal.

TROUBLE JUDGMENT


Check Conditions
  • The ignition switch is turned ON.
  • The engine speed is 600 r/min or more.
  • The battery backup voltage is 13.5 V or more.
  • The G-terminal duty ratio is 10.2 % or more and 89.8 % or less.
  • The FR-terminal duty ratio is 80 % or less and the malfunction of P0622 is not detected.
Judgement Criterion
  • For 30 seconds, the final target generation voltage subtracted from the battery backup voltage equals 0.8 V or more.


  • For 30 seconds, the battery backup voltage subtracted from the final target generation voltage equals 1.3 V or more.

FAIL-SAFE AND BACKUP FUNCTION



  • The restriction of the alternator output control against the electrical load is prohibited. (Normal alternator output control)

PROBABLE CAUSES



  • Failed battery
  • Failed alternator & failed drive belt
  • Failed connector contact
  • Disconnection, short and damage of alternator G-terminal circuit
  • Disconnection, short and damage of alternator L-terminal circuit
  • Damage of battery backup circuit
  • Failed alternator
  • Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Checking engine start conditions

  • Check whether the user uses the booster cable to start the engine.
note This diagnosis code can be output due to the battery voltage drop.

Q. Have you ever used the booster cable to start the engine?
Delete the diagnosis code and finish the check.
Go to Step 2.

Step 2. Battery check

  • Check the battery (Refer to GROUP 54A - Battery - On-vehicle Service - Battery Test ).

Q. Is the check result normal?
Go to Step 3.
Replace the battery.

STEP 3. Drive belt tension check

  • Drive belt tension check (Refer to GROUP 11C - On-vehicle Service - Drive belt tension check and adjustment )

Q. Is the check result normal?
Go to Step 4.
Replace the drive belt.

STEP 4. Connector check: B-09, B-10 engine-ECU connector and B-117 alternator connector

Q. Is the check result normal?
Go to Step 5.
Repair the connector.

STEP 5. Check harness between B-117 (terminal No. 1) alternator connector and B-10 (terminal No. 121) engine-ECU connector.

  • Check the disconnection, short and damage of the output line.

Q. Is the check result normal?
Go to Step 6.
Repair the harness.

STEP 6. Check harness between B-117 (terminal No. 3) alternator connector and B-09 (terminal No. 7) engine-ECU connector.



  • Check the disconnection, short and damage of the output line.

Q. Is the check result normal?
Go to Step 7.
Repair the harness.

STEP 7. Connector check: B-09, B-10 engine-ECU connector

Q. Is the check result normal?
Go to Step 8.
Repair the connector.

STEP 8. Check harness between battery and B-10 (terminal No. 103) engine-ECU connector.

  • Check the power supply line.

Q. Is the check result normal?
Go to Step 9.
Repair the harness.

STEP 9. Rechecking diagnosis code

Q. Is the diagnosis code output?
Go to Step 10.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).

STEP 10. Rechecking diagnosis code after replacing drive belt

  • Recheck whether the diagnosis code is output after replacing the drive belt

Q. Is the diagnosis code output?
Go to Step 11.
Finish the check.

STEP 11. Rechecking diagnosis code after replacing alternator

  • Recheck whether the diagnosis code is output after replacing the alternator.

Q. Is the diagnosis code output?
Replace the engine-ECU.
Finish the check.