P0622
DTC P0622: Generator FR Terminal Circuit MalfunctionGenerator Circuit:
CIRCUIT OPERATION
- The ECM
TECHNICAL DESCRIPTION
- When the generator field coils are controlled, the generator FR terminal inputs signal to the ECM
- The ECM
DTC SET CONDITIONS
Check Condition
- Engine speed is higher than 50 r/min.
Judgement Criterion
- 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)
- Generator failed.
- Open or shorted circuit in generator FR terminal circuit, harness damage or connector damage.
- ECM failed.
- PCM failed.
DIAGNOSIS
Required Special Tools:
- MB991958: Scan tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991910: Main Harness A
- MB991923: Power Plant ECU Check Harness
STEP 1. Check harness connector B-22 at ECM
Q: Is the harness connector in good condition?
YES: Go to Step 2.
NO: Repair or replace it. Then go to Step 8.
STEP 2. Measure the voltage at ECM
1. Disconnect all ECM
2. Start the engine and run at idle.
3. Measure the voltage between terminal No. 131 and ground.
NOTE: Vehicle for Canada, the headlight, taillight, etc. remain lit even when the lighting switch is in "OFF" position but this is no problem for checks.
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 drop.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Did the measured voltage drop?
YES: Go to Step 3.
NO: Go to Step 4.
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 the PCM. When the ECM or the PCM is replaced, register the encrypted code. Refer to Encrypted Code Registration Criteria Table. Then go to Step 8.
NO: It can be assumed that this malfunction is intermittent.
STEP 4. Check harness connector B-120 at generator connector for damage.
Q: Is the harness connector in good condition?
YES: Go to Step 5.
NO: Repair or replace it. Then go to Step 8.
STEP 5. Measure the voltage at generator harness side connector B-120.
1. Disconnect the connector B-120 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 7.
NO: Go to Step 6.
STEP 6. Check for open circuit and short circuit to ground between generator connector B-120 (terminal No. 4) and ECM
Q: Is the harness wire in good condition?
YES: Replace the ECM or the PCM. When the ECM or the PCM is replaced, register the encrypted code. Refer to Encrypted Code Registration Criteria Table. Then go to Step 8.
NO: Repair it. Then go to Step 8.
STEP 7. Check for harness damage between generator connector B-120 (terminal No. 4) and ECM
Q: Is the harness wire in good condition?
YES: Replace the generator. Then go to Step 8.
NO: Repair it. Then go to Step 8.
STEP 8. 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.