Engine Control Module: Testing and Inspection

Engine Control Module Voltage Supply, Checking

Special tools, testers and auxiliary items required

• Multimeter.

• Wiring diagram.

Test requirements

• Fuses SA14, SA15 and SA18 OK.

• Battery voltage at least 12.5 V.

• The Ground (GND) connections at the engine and transmission OK.

• The generator OK.

• The ignition is switched off.

Test procedure

- Perform a preliminary check to verify the customer's complaint. Refer to => [ Preliminary Check ] Preliminary Check.

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

- Connect the Test Box 105 Pin (VAG1598/42) with Adapter Cable (1598/39-1).

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

- Remove the Engine Control Module (ECM) (J623) => [ Engine Control Module, Replacing ] Engine Control Module, Replacing.

Checking voltage supply

Using a Multimeter, check the electrical harness connector terminals to the Engine Control Module (ECM) (J623) electrical harness connector terminals for voltage.





- Switch the ignition off.

Specified value: Battery voltage.

If the specified value was not obtained:

- Check the Engine Control Module (ECM) (J623) electrical harness connector terminal 92 to the Engine Control Module (ECM) Power Supply Relay (J363) terminal 3/86 for an open circuit or short to Ground (GND).

- Check the Engine Control Module (ECM) (J623) electrical harness connector terminal 69 to Engine Control Module (ECM) Power Supply Relay (J363) terminal 4/85 for an open circuit or short to Ground (GND).

If the specified values are not obtained:

- Check the electrical harness connectors for damage, corrosion, loose or broken terminals.

- If necessary, repair the wiring connection.

If no malfunctions are found in the wiring:

- Check the Engine Control Module (ECM) Power Supply Relay (J363). => [ Engine Control Module Power Supply Relay, Checking ] Engine Control Module Power Supply Relay, Checking

Checking Ground (GND)

- Using a Multimeter, check the following wiring connections for resistance.





Specified value: 1.5 ohms max.

If any of the specified values are not obtained:

- 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 and the voltage supply was OK:

- Perform a road test to verify any electrical repairs.

If the fault does not return:

Repair complete, Generate readiness code. Refer to => [ Readiness Code ] Monitors, Trips, Drive Cycles and Readiness Codes.

- End diagnosis.

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

- Replace the Engine Control Module (ECM) (J623). Refer to => [ Engine Control Module, Replacing ] Engine Control Module, Replacing.

- Assembly is performed in the reverse of the removal.

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 ] Diagnostic Mode 03 - Read DTC Memory.

2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Mode 04 - Erase DTC Memory.

3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code ] Monitors, Trips, Drive Cycles and Readiness Codes.