Positive Crankcase Ventilation Heating Element, Checking

Positive Crankcase Ventilation Heating Element, Checking

• Use only gold-plated terminals when servicing terminals in the electrical harness connector of Positive Crankcase Ventilation (PCV) Heating Element (N79).

Special tools, testers and auxiliary items required

• Multimeter.

• Wiring diagram.

Test requirements

• The Motronic Engine Control Module (ECM) (J220) fuses OK.

• The Power Supply Relay (terminal 50) (J682) 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

Checking internal resistance

- Disconnect the Positive Crankcase Ventilation (PCV) Heating Element (N79) electrical harness connector - 2 -.





- Using a multimeter, check the Positive Crankcase Ventilation (PCV) Heating Element (N79) terminals 1 to 2 for resistance.





Specified value: 25 to 35 ohms (at approx. 20° C)

If the specified value was not obtained:

- Replace the Positive Crankcase Ventilation (PCV) Heating Element (N79).

If the specified value was obtained:

Checking voltage

Switch the ignition on.

- Using a multimeter, check the Positive Crankcase Ventilation (PCV) Heating Element (N79) electrical connector terminal 1 to Ground (GND) for voltage.





Specified value: battery voltage.

Switch the ignition off.

If the specified value was not obtained:

- Check the wiring from the Positive Crankcase Ventilation (PCV) Heating Element (N79) electrical connector terminal 1 to the Power Supply Relay (terminal 50) (J682) socket 1/30 for a short circuit to Ground (GND), or an open circuit.

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

- If necessary, repair the wiring connection.

If no malfunctions are found in the wiring:

Checking Ground (GND)

- Using a multimeter, check the Positive Crankcase Ventilation (PCV) Heating Element (N79) electrical connector terminal 2 to Ground (GND) for continuity.





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, lose or broken terminals.

- If necessary, repair the faulty wiring connection.

If no malfunction is detected in the wiring:

- Replace the Positive Crankcase Ventilation (PCV) Heating Element (N79). Refer to => [ Motronic Engine Control Module, Replacing ] Motronic Engine Control Module, Replacing.

Final procedures

After 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.

- End of diagnosis.