Positive Crankcase Ventilation (PCV) Heating Element, Checking

Special tools and workshop equipment required 

• Multimeter.
• Wiring diagram.

Test requirements 

• The Motronic Engine Control Module (ECM) - J623- fuses OK.
• The Fuse 1 (on fuse panel C) -SC1- 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.

Checking internal resistance 

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

-- 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 -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 Fuse 1 (on fuse panel C) -SC1- 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 Wiring 

-- Using a multimeter --, check the Positive Crankcase Ventilation (PCV) Heating Element -N79- electrical connector terminal 2 to connector T94 terminal 93 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.

If no malfunction is detected in the wiring:

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

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 .