P0622

Generator Circuit Part 1:

Generator Circuit Part 2:

or PCM (terminal No. 54) apply a battery positive voltage into the generator FR terminal 4 via resistance inside the unit.

TECHNICAL DESCRIPTION
- When the generator field coils are controlled, the generator FR terminal inputs signal to the ECM or PCM .
- The ECM or PCM 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, harness damage, or connector damage.
- ECM failed.
- PCM failed.

DIAGNOSIS

Required Special Tools:
- MB991958: Scan Tool (MUT-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991911: Main Harness B

STEP 1. Check the voltage at generator connector B-45 by backprobing.

1. Do not disconnect the connector B-45.
2. Start the engine and run at idle.

3. Measure the voltage between terminal 4 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 be 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 connector B-45 at generator connector for damage.

Q: Is the connector in good condition?

YES: Go to Step 3.

NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 10.

STEP 3. 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. Start the engine and run at idle.
3. Read the DTC.
4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is DTC P0622 set?

YES: Replace the ECM or PCM. Then go to Step 10.

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

STEP 4. Check connector B-45 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 10.

STEP 5. Check the voltage at generator harness side connector B-45.

1. Disconnect the connector B-45 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 be 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 8.

NO: Go to Step 6.

STEP 6. Check connector C-58 at ECM or connector C-55 at PCM for damage.

Q: Is the connector in good condition?

YES: Go to Step 7.

NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 10.

STEP 7. Check for open circuit and short circuit to ground between generator connector B-45 (terminal No. 4) and ECM connector C-58 (terminal No. 52) or PCM connector C-55 (terminal No. 54) .

NOTE: Check harness after checking intermediate connector B-13. If intermediate connector is damaged, repair or replace them. Refer to Harness Connector Inspection. Then go to Step 10.

Q: Is the harness wire in good condition?

YES: Replace the ECM or PCM. Then go to Step 10.

NO: Repair it. Then go to Step 10.

STEP 8. Check connector C-58 at ECM or connector C-55 at PCM for damage.

Q: Is the connector in good condition?

YES: Go to Step 9.

NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 10.

STEP 9. Check for harness damage between generator connector B-45 (terminal No. 4) and ECM connector C-58 (terminal No. 52) or PCM connector C-55 (terminal No. 54) .

NOTE: Check harness after checking intermediate connector B-13. If intermediate connector is damaged, repair or replace them. Refer to Harness Connector Inspection. Then go to Step 10.

Q: Is the harness wire in good condition?

YES: Replace the generator. Then go to Step 10.

NO: Repair it. Then go to Step 10.

STEP 10. 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. Start the engine and run at idle.
3. Read the DTC.
4. Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is DTC P0622 set?

YES: Retry the troubleshooting.

NO: The inspection is complete.