MOTRONIC Engine Control Module Power Supply Relay, Checking

Special tools and workshop equipment required 

• Multimeter.
• Wiring diagram.

Test requirements 

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

  Courtesy of VOLKSWAGEN UNITED STATES, INC.
• Battery voltage at least 12.5 volts.
• All electrical consumers such as, lights and rear window defroster, switched off.
• Vehicles with automatic transmission, selector lever in position "P" or "N".
• A/C switched off.
• Ground connections between engine/transmission/chassis OK.
• Ignition switched off.

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 .

Test sequence 

-- Remove the Motronic Engine Control Module (ECM) Power Supply Relay -J271-.

Checking voltage 

-- Turn the ignition switch on.

-- Using a multimeter, check the Motronic Engine Control Module (ECM) Power Supply Relay -J271- socket 30 to ground.

-- Switch the ignition off.

Specified value: battery voltage.

If the specified value was not obtained:

-- Check the wiring connections from fuse 3 in Fuse Panel F to the Motronic Engine Control Module (ECM) Power Supply Relay -J271- socket 30 for high resistance, an open or short circuit.

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

-- If necessary, repair the faulty wiring connection.

If the specified value was obtained:

-- Switch the ignition on.

-- Using a multimeter, check the Motronic Engine Control Module (ECM) Power Supply Relay -J271- socket 86 to ground.

-- Switch the ignition off.

Specified value: battery voltage.

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.

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-.

-- Using a multimeter, check the Motronic Engine Control Module (ECM) Power Supply Relay -J271- to the Motronic Engine Control Module (ECM) -J623- electrical harness connector T94 for resistance.

Motronic Engine Control Module (ECM) Power Supply Relay -J271- socket terminal	Motronic Engine Control Module (ECM) -J623- electrical connector T94 terminal or test box socket
85	69

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.

If the specified value was obtained:

-- Replace the Motronic Engine Control Module (ECM) Power Supply Relay -J271-.

-- 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-.

-- 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 .