Code No. P0622: Alternator FR Terminal System








OPERATION



  • The energized state of the alternator field coil is inputted from the alternator (terminal No. 4) to the engine-ECU (terminal No. 61).

FUNCTION



  • A signal of the power supply duty ratio for the alternator field coil is inputted to the engine-ECU.
  • In response to the signal, the engine-ECU detects the alternator output current and controls the idling speed according to the output current (electric load).

TROUBLE JUDGMENT


Check Condition
  • Engine is running.
Judgement Criterion
  • Input voltage from the alternator FR terminal is approximately battery positive voltage for 20 seconds.
FAIL-SAFE AND BACKUP FUNCTION
  • Prohibits alternator output suppression control against current consumers.(Operates as a normal alternator.)

PROBABLE CAUSES



  • Failed alternator
  • Open circuit or harness damage in alternator circuit or loose connector contact
  • Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: B-115 alternator connector

Q. Is the check result normal?
Go to Step 2.
Repair or replace the connector.

STEP 2. Perform voltage measurement at B-115 alternator connector.

  • Disconnect connector, and measure at harness side.
  • Ignition switch: ON
  • Voltage between terminal No. 4 and earth.
OK: System voltage

Q. Is the check result normal?
Go to Step 6.
Go to Step 3.

STEP 3. Connector check: B-08 engine-ECU connector

Q. Is the check result normal?
Go to Step 4.
Repair or replace the connector.

STEP 4. Check harness between B-115 (terminal No. 4) alternator connector and B-08 (terminal No. 61) engine-ECU connector.

  • Check output line for open circuit.

Q. Is the check result normal?
Go to Step 5.
Repair the damaged harness wire.

STEP 5. M.U.T.-III diagnosis code

  • Reconfirmation of diagnosis code.

Q. Is diagnosis code set?
Replace the engine-ECU.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).

STEP 6. Connector check: B-08 engine-ECU connector

Q. Is the check result normal?
Go to Step 7.
Repair or replace the connector.

STEP 7. Check harness between B-115 (terminal No. 4) alternator connector and B-08 (terminal No. 61) engine-ECU connector.

  • Check output line for damage.

Q. Is the check result normal?
Go to Step 8.
Repair the damaged harness wire.

STEP 8. Perform voltage measurement at B-08 engine-ECU connector.

  • Disconnect engine-ECU connector, and connect special tool power plant ECU check harness (MB992110) to measure at connector for inspection.
  • Engine: Idle operation after warm-up
  • Transmission: P range
  • Radiator fan: Not operated
  • Voltage between terminal No. 61 and earth.
OK: The voltage decreases when the headlamp switch and the rear window defogger switch are turned ON from OFF.

Q. Is the check result normal?
Go to Step 5.
Replace the alternator.