Computers and Control Systems: Service and Repair
General Repair Information
• For the electric components to work properly, a voltage of at least 12.5 V is required.
• It is possible that the control module will recognize a malfunction and store a DTC during some tests. After completing all tests and repairs, DTC memory should therefore be checked and erased if necessary. Readiness code must be generated after DTC memory is erased => [ Readiness Code ] Readiness Code.
• If the engine only starts briefly and then turns off again after troubleshooting, repair or checking of the components, it may be that the immobilizer is blocking the Engine Control Module (ECM). DTC memory must then be checked and if necessary, control module must be adapted.
- Note radio code (for vehicles equipped with coded anti-theft radio / radio navigation system), determine if necessary.
- Switch ignition off and remove ignition key.
- Turn the locking mechanisms counter clockwise and remove them from the cover.
- Pull cover upward and remove.
• On vehicles equipped with Audi Telematics by OnStar(R), switch-off the emergency (back-up) battery for the Telematic/Telephone Control Module prior to disconnecting vehicle battery. Use must use the (VAS5051) or Vehicle Diagnosis & Service Syst. (VAS5052).
• The battery must only be disconnected and connected with the ignition switched off, since the Engine Control Module (ECM) can otherwise be damaged.
- Disconnect Ground (GND) wire at battery.
• Be sure to activate vehicle features (radio/radio-navigation system, clock, electric window regulators) according to owner's manual when the battery is re-connected.
• Deactivate service mode of Telematic Control Module.
• Generate readiness code => [ Readiness Code ] Readiness Code.
Final procedures
After reconnecting voltage supply, the following steps must be carried out in the order specified:
1. Retrieve DTC memory "Mode 3: Check DTC memory", => [ Diagnostic Mode 03 - Read DTC Memory ] Diagnostic Mode 03 - Read DTC Memory.
2. If necessary, erase DTC memory , => [ Diagnostic Mode 04 - Erase DTC Memory ] Clearing Diagnostic Trouble Codes.
3. Generate readiness code => [ Readiness Code ] Readiness Code.
- End diagnosis and switch ignition off.