Code No. P2426: EGR Cooling Valve Control Circuit (Low)

OPERATION

Power is supplied to the EGR cooler bypass control solenoid valve (terminal No. 2) from the engine control relay (terminal No. 1).
The engine-ECU (terminal No. 23) makes the power transistor in the unit be in "ON" position, and that makes currents go on the EGR cooler bypass control solenoid valve (terminal No. 1).

FUNCTION

By the signals from the engine-ECU, the EGR cooler bypass control solenoid valve takes control switching the pressure in the vacuum pump between the vacuum pressure and the atmospheric pressure.

TROUBLE JUDGMENT

Check Conditions

Battery positive voltage is 8 - 16 V.
2 seconds later after the ignition switch has been in "ON" position or the engine has started up.

Judgment Criterion

When the ECU command is "OPEN" and the valve position judged by the terminal voltage is "CLOSED".

FAIL-SAFE AND BACKUP FUNCTION

The EGR control is stopped (fully closed).

PROBABLE CAUSES

Failed EGR cooler bypass control solenoid valve
Open/short circuit or harness damage in EGR cooler bypass control solenoid valve circuit or loose connector contact
Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III actuator test

Item 31: EGR cooler bypass control solenoid valve

OK: Operating sound can be heard and the valve vibrates

Q. Is the check result normal?

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).

	Go to Step 2 .

STEP 2. Connector check: B-23 EGR cooler bypass control solenoid valve connector

Q. Is the check result normal?

	Go to Step 3 .

	Repair or replace the connector.

STEP 3. Perform resistance measurement at B-23 EGR cooler bypass control solenoid valve connector.

Disconnect connector, and measure at solenoid valve side.
Resistance between terminal No. 1 and No. 2.

OK: 29 - 35 Ω (at 20°C)

Q. Is the check result normal?

	Go to Step 4 .

	Replace the EGR cooler bypass control solenoid valve.

STEP 4. Perform voltage measurement at B-23 EGR cooler bypass control solenoid valve connector.

Disconnect connector, and measure at harness side.
Ignition switch: ON
Voltage between terminal No. 2 and earth.

OK: System voltage

Q. Is the check result normal?

	Go to Step 6 .

	Go to Step 5 .

STEP 5. Connector check: A-33X engine control relay connector

Q. Is the check result normal?

	Check intermediate connector A-11,and repair if necessary. If intermediate connector is normal, check and repair harness between B-23 (terminal No. 2) EGR cooler bypass control solenoid valve connector and A-33X (terminal No. 1) engine control relay connector. Check power supply line open/short circuit

	Repair or replace the connector.

STEP 6. Perform voltage measurement at B-39 engine-ECU connector.

Disconnect connector, and measure at harness side.
Ignition switch: ON
Voltage between terminal No. 23 and earth.

OK: System voltage

Q. Is the check result normal?

	Go to Step 8 .

	Go to Step 7 .

STEP 7. Connector check: B-39 engine-ECU connector

Q. Is the check result normal?

	Check and repair harness between B-23 (terminal No. 1) EGR cooler bypass control solenoid valve connector and B-39 (terminal No. 23) engine-ECU connector. Check output line for open/short circuit.

	Repair or replace the connector.

STEP 8. Connector check: B-39 engine-ECU connector

Q. Is the check result normal?

	Go to Step 9 .

	Repair or replace the connector.

STEP 9. Check harness between B-23 (terminal No. 1) EGR cooler bypass control solenoid valve connector and B-39 (terminal No. 23) engine-ECU connector.

Check output line for damage.

Q. Is the check result normal?

	Go to Step 10 .

	Repair the damaged harness wire.

STEP 10. Check harness between B-23 (terminal No. 2) EGR cooler bypass control solenoid valve connector and A-33X (terminal No. 1) engine control relay connector.

note

Before checking harness, check intermediate connector A-11, and repair if necessary.

Check power supply line for damage.

Q. Is the check result normal?

	Go to Step 11 .

	Repair the damaged harness wire.

STEP 11. M.U.T.-III actuator test

Item 31: EGR cooler bypass control solenoid valve

OK: Operating sound can be heard and the valve vibrates

Q. Is the check result normal?

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).

	Replace the engine-ECU.

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