Positive Crankcase Ventilation Heating Element, 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

  
• 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 PRELIMINARY CHECK 

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 Ω (at approx. 20° C)

If the specified value was not obtained:

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

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 Starter Relay -J53- socket 1/86 for a short circuit to Ground (GND), 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 (GND)

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

Specified value: 1.5 Ω 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.

-- 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:

Repair complete, Generate readiness code. Refer to READINESS CODE .

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

-- Replace the Motronic Engine Control Module (ECM) -J623-. Refer to the appropriate service manual.

-- Assembly is performed in the reverse of the removal.

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 .
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 .