Positive Crankcase Ventilation (PCV) Heating Element N79, Checking

Special tools and workshop equipment required 

• Multimeter.
• Wiring diagram.

Test requirements

• The Motronic Engine Control Module (ECM) - J623- fuses OK.
• The Power Supply Relay (terminal 50) -J682- OK.
  Fig 1: Fuses On E-Box In Engine Compartment, Left Side

  Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.
• 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 

-- Observe Clean Working Conditions. Refer to CLEAN WORKING CONDITIONS 

-- Perform a preliminary check to verify the customers complaint. Refer to 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 Ω (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 Ω 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 .

-- Perform a road test to verify repair.

If the DTC does not return:

Generate readiness code. Refer to 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 .
2. If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
3. If the DTC memory was erased, generate readiness code. Refer to READINESS CODE .