P0622

Generator Circuit:

Connectors:

Connectors:

CIRCUIT OPERATION
- The ECM (terminal No.52) or PCM (terminal No.54) apply 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 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 rpm.

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.
- PCM failed.

DIAGNOSIS

Generator Circuit:

Connectors:

DTC P0622: Generator FR Terminal Circuit Malfunction
Generator Circuit

647

Connectors:

CIRCUIT OPERATION
- The ECM (terminal No.52) or PCM (terminal No.54) apply 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 or PCM .
- The ECM or PCM detects the generator output with the input signal, and contr()1s the idle air control rnotor according to the generator output.

DTC SET CONDITIONS
Check Conditions
- Engine speed is higher than 50 rpm.

Judgement Criteria
- Input voltage from the generator FR terminal has continued to be approximately battery possitive 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.
- PCM failed.

DIAGNOSIS

STEP 1. Measure the voltage at generator connector B-13 by backprobing.

1. Do not disconnect the connector B-13.
2. Start the engine and run at idle.
3. Measure the voltage between terminal No.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: Is the voltage normal?

YES: Go to Step 2.
NO: Go to Step 4.

STEP 2. Check connector B-13 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 MB991502, read the diagnostic trouble code (DTC).

CAUTION: To prevent damage to scan tool MB991502, always turn the Ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.

1. Connect scan tool MB991502 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 INTRODUCTION, How to Use Troubleshooting/Inspection Service Points.

STEP 4. Check connector B-13 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. Measure the voltage at generator harness side connector B-13.

1. Disconnect the connector B-13 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.

Connectors:

STEP 6. Check connector C-118 at ECM or connector C-115 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.

Connectors:

STEP 7. Check for open circuit and short circuit to ground between generator connector B-13 (terminal No.4) and ECM connector C-118 (terminal No.52) or PCM connector C-115 (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.

Connectors:

STEP 8. Check connector C-118 at ECM or connector C-115 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.

Connectors:

STEP 9. Check for harness damage between generator connector B-13 (terminal No.4) and ECM connector C-118 (terminal No.52) or PCM connector C-115 (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 scantool MB991502, read the diagnostic trouble code (DTC).

CAUTION
To prevent damage to scan tool MB991502, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991502.

1. Connect scan toot MB991502 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.