Knock Sensor 2, Checking

Observe all safety precautions: SAFETY PRECAUTIONS 

View clean working conditions: CLEAN WORKING CONDITIONS 

Use only gold-plated terminals when servicing any component with gold-plated electrical harness connector terminals.

For wiring diagrams, component locations, and connector views, Refer to the applicable wiring diagram.

Special tools and workshop equipment required 

• Multimeter.
• Wiring diagram.

Test requirements

• The mounting bolt of Knock Sensor (KS) 2 -G66- tightened to 20 Nm.
• The Motronic Engine Control Module (ECM) - J623- fuses 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.

Test procedure

-- Perform a preliminary check to verify the customers complaint. Refer to PRELIMINARY CHECK 

Start diagnosis

-- Remove the engine cover with air filter. Refer to appropriate service manual.

Fig 2: Air Filter Components

-- Disconnect the Knock Sensor (KS) 2 -G66- electrical harness connector -arrow-.

Fig 3: Location of Engine Speed (RPM) Sensor -G28-

Checking internal resistance

-- Using a multimeter, check the Knock Sensor (KS) 2 -G66- terminals 1 to 2 for an internal short.

Fig 4: Identifying Engine Speed (RPM) Sensor G28 Terminals

Specified value: ∞ (Infinity).

If the specified value was not obtained:

-- Replace the faulty Knock Sensor (KS) 2 -G66-. Refer to appropriate service manual.

If the specified value was obtained:

Checking wiring

If the manufacturers test box is being used, perform the following step.

-- Install the test box.

If the manufacturers test box is not being used, perform the following step.

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

-- Using a multimeter, Check the Knock Sensor (KS) 2 -G66- electrical harness connector to the Motronic Engine Control Module (ECM)J623 electrical harness connector T60 for an open circuit.

Fig 5: Identifying 3-Pin Connector

Specified value: 1.5 Ω Max.

If the specified value was not obtained:

-- Check the wiring connection for an open circuit.

-- Check the wiring connection for damage, corrosion, loose or broken terminals.

-- If necessary, repair the faulty wiring connection.

If no malfunction is found in the wiring and the resistance was not OK:

-- Replace the faulty Knock Sensor (KS) 2 -G66-. Refer to appropriate service manual.

If no malfunction is found in the wiring and the resistance was OK:

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

-- Install the engine cover with air filter. Refer to appropriate service manual.

Final procedures

After the 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 .