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-A/T-ECU (terminal No. 54).

FUNCTION

A signal of the power supply duty ratio for the alternator field coil is inputted to the engine-A/T-ECU.

In response to the signal, the engine-A/T-ECU detects the alternator output current and controls the idling speed according to the output current (electric load).

TROUBLE JUDGMENT

Check Condition

Engine speed of 50 r/min or more <SOHC>.

Engine speed of 500 r/min or more <DOHC>.

Judgment Criterion

Input voltage from alternator FR terminal continues to be below 4.5 V for 20 seconds. <SOHC>

Input voltage from alternator FR terminal continues to be 4.8 - 5.2 V or battery voltage for 20 seconds <DOHC>.

PROBABLE CAUSE

Alternator FR terminal circuit open circuited

Failed engine-A/T-ECU

DIAGNOSIS PROCEDURE

STEP 1. Connector check: B-19 intermediate connector

Q: Is the check result normal?

YES: Go to Step 2

.
NO: Repair.

STEP 2. Perform voltage measurement at B-19 intermediate connector.

Disconnect connector, and measure at male connector side.

Ignition switch: ON

Voltage between terminal No. 1 and earth.

OK: 4.9 - 5.1 V

Q: Is the check result normal?

YES: Go to Step 6

.
NO: Go to Step 3

STEP 3. Connector check: C-111 engine-A/T-ECU connector

Q: Is the check result normal?

YES: Go to Step 4

.
NO: Repair.

STEP 4. Check harness between B-19 (terminal No. 1) intermediate connector and C-111 (terminal No. 54) engine-A/T-ECU connector.

Check output line for short circuit.

Q: Is the check result normal?

YES: Go to Step 5

.
NO: Repair.

STEP 5. Check the trouble symptoms.

Q: Does trouble symptom persist?

YES: Replace engine-A/T-ECU.
NO: Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points

STEP 6. Perform voltage measurement at B-19 intermediate connector.

Use special tool test harness (MB991658) to connect connector, and measure at pick-up harness.

Ignition switch: ON

Voltage between terminal No. 1 and earth.

OK: 5 - 6 V

Q: Is the check result normal?

YES: Go to Step 9

.
NO: Go to Step 7

STEP 7. Connector check: B-30 alternator connector

Q: Is the check result normal?

YES: Go to Step 8

.
NO: Repair.

STEP 8. Check harness between B-30 (terminal No. 4) alternator connector and B-19 (terminal No. 1) intermediate connector.

Check output line for short circuit.

Q: Is the check result normal?

YES: Replace alternator.
NO: Repair.

STEP 9. Perform voltage measurement at B-19 intermediate connector.

Use special tool test harness (MB991658) to connect connector, and measure at pick-up harness.

Engine: Idle after warm-up

Selector lever position: P

Radiator fan: Inactive

Voltage between terminal No. 1 and earth.

OK: Switching the headlamps to ON from OFF causes the voltage to fall.

Q: Is the check result normal?

YES: Go to Step 5

.
NO: Go to Step 10

STEP 10. Connector check: B-30 alternator connector

Q: Is the check result normal?

YES: Go to Step 11

.
NO: Repair.

STEP 11. Check harness between B-30 (terminal No. 4) alternator connector and B-19 (terminal No. 1) intermediate connector.

Check output line for damage.

Q: Is the check result normal?

YES: Go to Step 12

.
NO: Repair.

STEP 12. Check harness between B-19 (terminal No. 1) intermediate connector and C-111 (terminal No. 54) engine-A/T-ECU connector.

Check output line for damage.

Q: Is the check result normal?

YES: Go to Step 13

.
NO: Repair.

STEP 13. Check trouble symptom.

Q: Same symptoms regenerated?

YES: Replace alternator.
NO: Intermittent malfunction (Refer to Group 00 - How to Use troubleshooting/Inspection Service Points


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-A/T-ECU (terminal No. 54).
FUNCTION A signal of the power supply duty ratio for the alternator field coil is inputted to the engine-A/T-ECU. In response to the signal, the engine-A/T-ECU detects the alternator output current and controls the idling speed according to the output current (electric load).
TROUBLE JUDGMENT Check Condition Engine speed of 50 r/min or more <SOHC>. Engine speed of 500 r/min or more <DOHC>. Judgment Criterion Input voltage from alternator FR terminal continues to be below 4.5 V for 20 seconds. <SOHC> Input voltage from alternator FR terminal continues to be 4.8 - 5.2 V or battery voltage for 20 seconds <DOHC>.
PROBABLE CAUSE Alternator FR terminal circuit open circuited Failed engine-A/T-ECU
	DIAGNOSIS PROCEDURE

	STEP 1. Connector check: B-19 intermediate connector
	Q: Is the check result normal? YES: Go to Step 2 . NO: Repair.
	STEP 2. Perform voltage measurement at B-19 intermediate connector.
	Disconnect connector, and measure at male connector side. Ignition switch: ON Voltage between terminal No. 1 and earth. OK: 4.9 - 5.1 V Q: Is the check result normal? YES: Go to Step 6 . NO: Go to Step 3 .
	STEP 3. Connector check: C-111 engine-A/T-ECU connector
	Q: Is the check result normal? YES: Go to Step 4 . NO: Repair.
	STEP 4. Check harness between B-19 (terminal No. 1) intermediate connector and C-111 (terminal No. 54) engine-A/T-ECU connector.
	Check output line for short circuit. Q: Is the check result normal? YES: Go to Step 5 . NO: Repair.
	STEP 5. Check the trouble symptoms. Q: Does trouble symptom persist? YES: Replace engine-A/T-ECU. NO: Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points ).
	STEP 6. Perform voltage measurement at B-19 intermediate connector.
	Use special tool test harness (MB991658) to connect connector, and measure at pick-up harness. Ignition switch: ON Voltage between terminal No. 1 and earth. OK: 5 - 6 V Q: Is the check result normal? YES: Go to Step 9 . NO: Go to Step 7 .
	STEP 7. Connector check: B-30 alternator connector
	Q: Is the check result normal? YES: Go to Step 8 . NO: Repair.
	STEP 8. Check harness between B-30 (terminal No. 4) alternator connector and B-19 (terminal No. 1) intermediate connector.
	Check output line for short circuit. Q: Is the check result normal? YES: Replace alternator. NO: Repair.
	STEP 9. Perform voltage measurement at B-19 intermediate connector.
	Use special tool test harness (MB991658) to connect connector, and measure at pick-up harness. Engine: Idle after warm-up Selector lever position: P Radiator fan: Inactive Voltage between terminal No. 1 and earth. OK: Switching the headlamps to ON from OFF causes the voltage to fall. Q: Is the check result normal? YES: Go to Step 5 . NO: Go to Step 10 .
	STEP 10. Connector check: B-30 alternator connector
	Q: Is the check result normal? YES: Go to Step 11 . NO: Repair.
	STEP 11. Check harness between B-30 (terminal No. 4) alternator connector and B-19 (terminal No. 1) intermediate connector.
	Check output line for damage. Q: Is the check result normal? YES: Go to Step 12 . NO: Repair.
	STEP 12. Check harness between B-19 (terminal No. 1) intermediate connector and C-111 (terminal No. 54) engine-A/T-ECU connector.
	Check output line for damage. Q: Is the check result normal? YES: Go to Step 13 . NO: Repair.
	STEP 13. Check trouble symptom. Q: Same symptoms regenerated? YES: Replace alternator. NO: Intermittent malfunction (Refer to Group 00 - How to Use troubleshooting/Inspection Service Points ).