Engine Coolant Temperature Sensor, Checking

Engine Coolant Temperature Sensor, Checking

CAUTION!
• Cooling system is under pressure.

• Danger of scalding when opening!

• Use only gold-plated terminals when servicing terminals in the electrical harness connector of Engine Coolant Temperature (ECT) Sensor (G62).

Special tools, testers and auxiliary items required

• Multimeter.

• jumper wire.

• Wiring diagram.

Test requirements

• The Diesel Direct Fuel Injection (DFI) Engine Control Module (ECM) (J248) fuses OK.

• Battery voltage at least 12.5 volts.

• All electrical consumers such as, lights and rear window defroster, switched off.

• Vehicles with automatic transmission, shift selector lever into position "P" or "N".

• A/C switched off.

• Ground (GND) connections between engine/transmission/chassis OK.

• Ignition switched off.

• Engine cold.

Test procedure

- Perform a preliminary check to verify the customers complaint. Refer to => [ General Diagnosis ] General Diagnosis.

Start diagnosis

- Perform the function test in diagnostic mode 06. Refer to => [ Diagnostic Mode 06 - Read Test Results for Specific Diagnostic Functions ] Diagnostic Mode 06 - Read Test Results for Specific Diagnostic Functions.

If the specified values were not obtained:

Checking internal resistance

- Disconnect the Engine Coolant Temperature (ECT) Sensor (G62) electrical harness connector.





- Using a multimeter, check the Engine Coolant Temperature (ECT) Sensor (G62) terminals 1 to 2 for resistance.

Use the chart below for the specified values:





• Area A: Resistance values 0 to 50° C (32° - 122° F).

• Area B: Resistance values 50 to 100° C (122° - 212° F).

Examples:

• Range A, 30° C (86° F) equals a resistance of 1500 to 2000 ohms

• Range B, 80° C (176° F) equals a resistance of 275 to 375ohms

If any of the specified values were not obtained:

- Replace the Engine Coolant Temperature (ECT) Sensor (G62).

If the specified values were obtained:

Checking wiring

If the manufacturers test box is being used, perform the following step.

- Install the test box. Refer to => [ 68-Pin Test Box Adapter, VAG1598/19, Installing ] Diesel Direct Fuel Injection ECM, Checking.

If the manufacturers test box is not being used, perform the following step.

- Remove the Diesel Direct Fuel Injection (DFI) Engine Control Module (ECM) (J248). Refer to => [ Diesel Direct Fuel Injection ECM, Replacing ] Diesel Direct Fuel Injection ECM, Checking.

- Using a Multimeter, check the Engine Coolant Temperature (ECT) Sensor (G62) electrical harness connector terminals to the Diesel Direct Fuel Injection (DFI) Engine Control Module (ECM) (J248) electrical harness connector T60 terminals for resistance.









Specified value: 1.5 ohms Max.

If the specification was not obtained:

- Check the wiring for a short circuit to each other, Battery (+), and Ground (GND).

- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

- If necessary, repair the faulty wiring connection.

If no malfunction is detected in the wiring:

- Erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Mode 04 - Erase DTC Memory.

- Perform a road test to verify repair.

If the DTC does not return:

Repair complete, Generate readiness code. Refer to => [ Readiness Code ] Readiness Code.

- End diagnosis.

If the DTC does return and no malfunction is detected in the wiring and the voltage supply was not OK:

- Replace the Diesel Direct Fuel Injection (DFI) Engine Control Module (ECM) (J248). Refer to => [ Diesel Direct Fuel Injection ECM, Replacing ] Diesel Direct Fuel Injection ECM, Checking.

- Assembly is performed in the reverse of the removal.

Final procedures

After the repair work, the following work steps must be performed in the following sequence:

1. Check the DTC memory. Refer to => [ Diagnostic Mode 03 - Read DTC Memory ] Diagnostic Mode 03 - Read DTC Memory.

2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Mode 04 - Erase DTC Memory.

3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code ] Readiness Code.