VOLTAGE SUPPLY, CHECKING Audi A3 8P facelift

VOLTAGE SUPPLY, CHECKING

Special tools and workshop equipment required

1. Multimeter.
2. Wiring diagram.

Test requirements

1. The Motronic Engine Control Module (ECM) - J220- fuses OK.
2. Battery voltage at least 12.5 volts.
3. All electrical consumers such as, lights and rear window defroster, switched off.
4. Vehicles with automatic transmission, selector lever in position "P" or "N".
5. A/C switched off.
6. Ground (GND) connections between engine/transmission/chassis OK.
7. Ignition switched off.

Test procedure

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

Start diagnosis

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

Checking voltage

Using a Multimeter, check the Motronic Engine Control Module (ECM) Power Supply Relay -J271- socket 1/30 to Ground (GND).

Specified value: battery voltage.

If the specified value was not obtained

Check the wiring connections from the Battery to the Motronic Engine Control Module (ECM) Power Supply Relay -J271- socket 1/30 for an open circuit or a short circuit.

Check the wiring connections for damage, corrosion, lose 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 3/86 to Ground (GND).

Specified value: battery voltage.

If the specified value was obtained

Checking wiring

If the manufacturers test box is being used. Perform the following step.

Install the test box. Refer to Repair information.

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

Remove the Motronic Engine Control Module (ECM) -J220-. Refer to Repair information.

Using a Multimeter, check the Motronic Engine Control Module (ECM) Power Supply Relay -J271- socket 3/86 to the Motronic Engine Control Module (ECM) -J220- electrical harness connector T94 terminal 92 for resistance.

Specified value: 2.0 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, lose or broken terminals.

If necessary, repair the faulty wiring connection.

If no malfunction is found in the wiring

Checking activation

Switch the ignition on.

Using a Multimeter, check the Motronic Engine Control Module (ECM) Power Supply Relay -J271- socket 4/85 to the Motronic Engine Control Module (ECM) -J220- electrical harness connector T94 terminal 69 for voltage.

Switch the ignition off.

Specified value: 0.5 V Max.

If the specified value was obtained

Replace the Motronic Engine Control Module (ECM) Power Supply Relay -J271- : Refer to Repair information.

If the specified value was not obtained

Check the wiring connection for an open circuit, short circuit to Battery (+) or Ground (GND).

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

If necessary, repair the faulty wiring connection.

If no malfunction is found in the wiring and voltage supply was not OK

Replace the Motronic Engine Control Module (ECM) -J220-. Refer to Repair information.

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»(ref-496054-S19296251252012082100000) .
2. If necessary, erase the DTC memory. Refer to «DIAGNOSTIC MODE 04 - ERASE DTC MEMORY»(ref-496054-S06987146602012082100000) .
3. If the DTC memory was erased, generate readiness code. Refer to «READINESS CODE»(ref-496054-S23770317242012082100000) .