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

OPERATION

Power is supplied to the EGR cooler bypass control solenoid valve connector terminal from the engine control relay connector terminal.
The engine-ECU connector terminal EGC makes the power transistor in the unit be in "ON" position, and that makes currents go on the EGR cooler bypass control solenoid valve connector terminal.

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. Perform resistance measurement at EGR cooler bypass control solenoid valve connector.

EGR cooler bypass control solenoid valve connector check.
Disconnect connector, and measure at solenoid valve side.
Resistance between terminals.

OK: 29 - 35 Ω (at 20°C)

Q. Is the check result normal?

	Go to Step 3.

	Repair or replace the connector, or replace the EGR cooler bypass control solenoid valve.

STEP 3. Perform voltage measurement at EGR cooler bypass control solenoid valve connector.

Disconnect connector, and measure at harness side.
Ignition switch: ON
Voltage between terminal power supply line and body earth.

OK: System voltage

Q. Is the check result normal?

	Go to Step 4.

	Repair or replace the connector, or check and repair harness between EGR cooler bypass control solenoid valve connector terminal and engine control relay connector terminal. Check power supply line open/short circuit

STEP 4. Perform voltage measurement at engine-ECU connector.

Disconnect connector, and measure at harness side.
Ignition switch: ON
Voltage between terminal EGC and body earth.

OK: System voltage

Q. Is the check result normal?

	Go to Step 5.

	Repair or replace the connector, or check and repair harness between EGR cooler bypass control solenoid valve connector terminal and engine-ECU connector terminal EGC. Check output line for open/short circuit.

STEP 5. Check harness between EGR cooler bypass control solenoid valve connector terminal and engine-ECU connector terminal EGC.

Check output line for damage.

Q. Is the check result normal?

	Go to Step 6.

	Repair or replace the connector, or repair the damaged harness wire.

STEP 6. Check harness between EGR cooler bypass control solenoid valve connector terminal and engine control relay connector terminal.

Check power supply line for damage.

Q. Is the check result normal?

	Go to Step 7.

	Repair or replace the connector, or repair the damaged harness wire.

STEP 7. 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.