Audi Q7 Quattro Owner’s Manual

Audi Q7 Quattro

Introduction

2007 Audi Q7 Quattro (4LB) V6-3.6L (BHK) Vehicle > Powertrain Management > Emission Control Systems > Positive Crankcase Ventilation > PCV Heater> Testing and Inspection> Component Tests and General Diagnostics

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) (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 (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] See: Computers and
    Control Systems > Scan Tool Testing and Procedures > 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 ohms (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 ohms 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] See: Computers and Control Systems

  • Scan Tool Testing and Procedures > Diagnostic Mode 04 – Erase DTC Memory

• Perform a road test to verify repair.
  If the DTC does not return:

If the DTC does not return:
Repair complete, Generate readiness code. Refer to [Readiness Code ] See: Computers and Control Systems > Monitors, Trips, Drive Cycles and Readiness Codes> 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] See: Computers and Control Systems
   • Scan Tool Testing and Procedures > Diagnostic Mode 03 – Read DTC Memory.
2. If necessary, erase the DTC memory. Refer to [Diagnostic Mode 04 – Erase DTC Memory] See: Computers and Control Systems > Scan Tool Testing and Procedures > Diagnostic Mode 04 – Erase DTC Memory.
3. If the DTC memory was erased, generate readiness code. Refer to [Readiness Code] See: Computers and Control Systems > Monitors, Trips, Drive Cycles and Readiness Codes > Readiness Code.

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