Voltage Supply, Checking Audi TT 8N

Special tools, testers and auxiliary items required

1. Multimeter.
2. Wiring diagrams.

Test requirements

1. Fuse S132 OK.
2. Fuse S134 OK.
3. Fuse S138 OK.
4. Fuse S237 OK.

1. The Ground (GND) connections at the engine and transmission OK.
2. The battery voltage at least 12.5 V.
3. The generator OK.

Test procedure

1. Perform a preliminary check to verify the customers complaint. Refer to --> «General Diagnosis»(ref-276276-S40851803372008010300000) .

Start diagnosis

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

1. Install the Adapter Cable (121-pin) VAG1598/31. Refer to --> «24 MULTIPORT FUEL INJECTION (MFI)»(ref-276275-S13244009452008010300000) .

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

1. Remove the Motronic Engine Control Module (ECM) J220. Refer to --> «Motronic Engine Control Module (ECM) J220, Replacing»(ref-276276-S39982482672008010300000) .

Checking voltage supply

1. Using a Multimeter , check the following wiring connection for voltage.

Specified value: 12.5 V

If the specified value was not obtained

1. Check the Motronic Engine Control Module (ECM) J220 electrical harness connector terminal 28/DF to Generator (GEN) C terminal W for an open circuit or short to Ground (GND).
2. Check the electrical harness connectors for damage, corrosion, loose or broken terminals.
3. If necessary, repair the wiring connection.

If no malfunctions are found in the wiring

1. Switch the ignition on.
2. Using a Multimeter , check the following wiring connection for voltage.

Specified value: 12.5 V

1. Switch the ignition off.

If the specified value was not obtained

1. Check the Motronic Engine Control Module (ECM) J220 electrical harness connector terminal 3/15 to the Motronic Engine Control Module (ECM) Power Supply Relay J271 socket 2/87 for an open circuit or short to Ground (GND).
2. Check the electrical harness connectors for damage, corrosion, loose or broken terminals.
3. If necessary, repair the wiring connection.

If no malfunctions are found in the wiring

Checking Ground (GND)

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

Specified value: 1.5 ohms.

If any of the specified values are not obtained

1. Check the Motronic Engine Control Module (ECM) J220 electrical harness connector terminals to the following Ground (GND) locations for an open circuit or a short to Battery (+).

1. Check the electrical harness connector for damage, corrosion, loose or broken terminals.
2. If necessary, repair the wiring connection.

If no malfunctions are found in the wiring and the voltage supply was OK

1. Perform a road test to verify any electrical repairs.

If the fault does not return

Repair complete, Generate readiness code. Refer to --> Readiness Code .

1. End of diagnosis.

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

1. Replace the Motronic Engine Control Module (ECM) J220. Refer to --> «Motronic Engine Control Module (ECM) J220, Replacing»(ref-276276-S39982482672008010300000) .
2. 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.
2. If necessary, erase the DTC memory. Refer to «Diagnostic Mode 04: Reset/Delete Diagnostic Data»(ref-276276-S31279847122008010300000) .
3. If the DTC memory was erased, generate readiness code. Refer to «Readiness Code»(ref-276276-S05799074302008010300000) .

End of diagnosis.