Positive Crankcase Ventilation (PCV) Heating Element N79, Checking

Diagnostic Procedures

Positive Crankcase Ventilation (PCV) Heating Element N79, Checking

• Use only gold-plated terminals when servicing terminals in the electrical harness connector of the Engine Speed (RPM) Sensor (G28).

Special tools, testers and auxiliary items required

• Multimeter.

• Wiring diagram.

Test requirements

• The Motronic Engine Control Module (ECM) (J623) 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 connections between engine/transmission/chassis OK.

• Ignition switched off.

• Engine cold.

Test procedure

- Observe safety precautions. Refer to => [ Safety Precautions ] Safety Precautions

- Observe Clean Working Conditions. Refer to => [ Clean Working Conditions ] Clean Working Conditions

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

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: 7 to 12 ohms (at approx. 20° C)

If the specified value was not obtained:

- Replace the Positive Crankcase Ventilation (PCV) Heating Element (N79). Refer to the Repair Information.

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 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 fuse 18 in Fuse Panel C for high resistance, a short circuit to ground or an open circuit.

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

- If necessary, repair the wiring connection.

If no malfunctions are found in the wiring:

Checking Ground

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





Specified value: 1.5 ohms Max.

If the specification was not obtained:

- Check the wiring for an open, high resistance or short circuit to voltage or ground.

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

- If necessary, repair the faulty wiring connection.

- Erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 09.

- Perform a road test to verify repair.

If the DTC does not return:

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

If the DTC does return, no malfunction is detected in the wiring and the voltage supply is OK:

- Replace the Motronic Engine Control Module (ECM) (J623). Refer to the Repair Information.

- Assembly is performed in the reverse of the removal.

Final procedures

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

1. Check the DTC memory. Refer to => [ Diagnostic Mode 03 - Read DTC Memory ] Diagnostic Modes 01 - 09.

2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 09.

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