Motronic Engine Control Module Power Supply Relay, Checking

Motronic Engine Control Module Power Supply Relay, Checking

Special tools, testers and auxiliary items required

• Multimeter

• wiring diagrams

• The manufacturers test box Test Box 105 Pin (VAG1598/42) is available for purchase or rental.

Test requirements

• The fuse for the engine electronics OK.

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

• The battery voltage at least 12.5 V.

• The generator OK.

• The ignition is switched off.

Test procedure

- Perform a preliminary check to verify the customers complaint. Refer to --> [ Preliminary Check ] Preliminary Check

Start diagnosis

Test sequence

- Switch the ignition on.

- Using the Multimeter, check the following wiring connections for voltage.





Specified value: 12.5. battery voltage.

- Switch the ignition off.

If the specified values are not obtained:

- Using the Multimeter, check the wiring connections for an open circuit.

Specified value: Wire resistance max 1.5 ohms.

- If necessary, repair the wiring connection.

- Erase the DTC memory. Refer to --> [ Diagnostic Mode 04 - Erase DTC Memory ] Clearing Diagnostic Trouble Codes

- Perform a road test to verify repair.

If the DTC does not return:

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

- End diagnosis.

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 --> [ Motronic Engine Control Module, Replacing ] Motronic Engine Control Module, Replacing.

- Assembly is performed in the reverse of the removal.

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 ] Reading Diagnostic Trouble Codes.

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

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