P0622

DTC P0622: Generator FR Terminal Circuit Malfunction

Generator Circuit:

CIRCUIT OPERATION
- The ECM (terminal 41) applies a battery positive voltage into the generator FR terminal No. 4 via resistance inside the unit.

TECHNICAL DESCRIPTION
- When the generator field coils are controlled, the generator FR terminal inputs signal to the ECM.
- The ECM detects the generator output with the input signal, and controls the idle air control motor according to the generator output.

DTC SET CONDITIONS

Check Conditions
- Engine speed is higher than 50 r/min.

Judgement Criteria
- Input voltage from the generator FR terminal has continued to be approximately battery positive voltage for 20 seconds.

TROUBLESHOOTING HINTS (The most likely causes for this code to be set area:)
- Open circuit in generator FR terminal circuit.
- ECM failed.

DIAGNOSIS

STEP 1. Measure the voltage at generator intermediate connector B-14 by backprobing.




1. Do not disconnect connector B-14.
2. Start the engine and run at idle.




3. Measure the voltage between terminal No. 5 and ground by backprobing
a. Engine: warming up
b. Radiator fan: stopped
c. Headlight switch: OFF to ON
d. Rear defogger switch: OFF to ON
e. Stoplight switch: OFF to ON
- Voltage should measure drops.

4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Did the measured voltage drop?

YES: Go to Step 2.

NO: Go to Step 4.




STEP 2. Check harness connector B-14 at generator intermediate connector for damage.

Q: Is the harness connector in good condition?

YES: Go to Step 3.

NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 11.

STEP 3. Retest the system.

1. Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Procedure 6 - Other Monitor. OBD-II Drive Cycle Pattern Lists
2. Check the diagnostic trouble code (DTC).

Q: Is DTC P0622 set?

YES: Replace the ECM. Then go to Step 11.

NO: It can be assumed that this malfunction is intermittent. Refer to How to Use Troubleshooting/Inspection Service Points.




STEP 4. Check connector B-14 at generator intermediate connector for damage.

Q: Is the connector in good condition?

YES: Go to Step 5.

NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 11.




STEP 5. Check harness connector B-25 at generator connector for damage.

Q: Is the harness connector in good condition?

YES: Go to Step 6.

NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 11.

STEP 6. Measure the voltage at generator harness side connector B-25.




1. Disconnect connector B-25 and measure at the harness side.
2. Turn the ignition switch to the "ON" position.




3. Measure the voltage between terminal No. 4 and ground.
- Voltage should measure battery positive voltage.

4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is battery positive voltage (approximately 12 volts) present?

YES: Go to Step 9.

NO: Go to Step 7.




STEP 7. Check harness connector C-119 at ECM for damage.

Q: Is the harness connector in good condition?

YES: Go to Step 8.

NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 11.







STEP 8. Check for open circuit and short circuit to ground between generator connector B-25 (terminal No. 4) and ECM connector C-119 (terminal No. 41).

Q: Is the harness wire in good condition?

YES: Replace the ECM. Then go to Step 11.

NO: Repair it. Then go to Step 11.




STEP 9. Check harness connector C-119 at ECM for damage.

Q: Is the harness connector in good condition?

YES: Go to Step 10.

NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 11.







STEP 10. Check for harness damage between generator connector B-25 (terminal No. 4) and ECM connector C-119 (terminal No. 41).

Q: Is the harness wire in good condition?

YES: Replace the generator. Then go to Step 11.

NO: Repair it. Then go to Step 11.




STEP 11. Using scan tool MB991958, read the diagnostic trouble code (DTC)

CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.

1. Connect scan tool MB991958 to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. Read the DTC.
4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is DTC P0622 set?

YES: Repeat the troubleshooting.

NO: The procedure is complete.