Keyless Systems - Intermittent No Start Using Button
96 Engine intermittently or consistently does not start using advance key start button, starts w/ key & ignition switch96 09 16
2010941/6
November 24, 2009.
Supersedes Technical Service Bulletin Group 96 number 08-13 dated November 14, 2008 for reasons listed below.
Affected Vehicles
Condition
Customer states that engine does not start or intermittently does not start when Advance Key engine start button is depressed. Engine will start using ignition key and ignition switch.
Technical Background
May be caused by:
A - Mechanical issue with the engine start button.
B - Electrical issue with the engine stop button.
Production Solution
Production (B only)
Updated access start control unit software.
Service
Tip: If the vehicle exhibits battery discharging and the diagnosis of the engine start / stop button is determined to be a software issue based on the criteria in section B - Electrical issue with the engine stop button, please perform update flash as outlined in TSB 2019143. Otherwise proceed with this TSB.
Perform the following only if condition is accompanied by a customer concern.
A - Mechanical issue with the engine start button
Rationale
Engine start button has two detents. Similar to ignition switch, the first detent will activate 15 power. Second detent activates starter.
When depressing engine start button, flow from initial push through to second detent should be smooth; audible clicks should be heard as detents are reached.
In some cases, second detent, starter activation, cannot be achieved due to mechanical tolerances within the switch.
Procedure
1. Interrogate fault memory of access start control unit, address word (05), with VAS 5051/5052.
a. If no fault is found in access start control unit, check engine start button functionality by observing measuring value block 2, fields 1 and 2, of access start control unit.
-- If engine start button is found to be non-functional, replace Advance Key engine start / engine stop switch.
Refer to Repair Manual >> Group 96 - Lights, Switches >> Interior, AntiTheft for appropriate repair procedure.
b. If DTC 02764 008 (Button for start/access authorization - incorrect signal) is found in access start control unit, go to B Electrical issue with the engine stop button below.
B - Electrical issue with the engine stop button
Rationale
Engine stop button has two internal micro switches, activated when the button is depressed.
Both micro switches send a signal independently of one another to access start control unit. When access start control unit receives both signals within three seconds, access start control unit disables the engine, as long as vehicle is stationary.
In some instances, the engine stop button may be held down lightly but not in the fully depressed position. For instance, there may be a cell phone resting on the button. In this case, the access start control unit receives only one micro switch signal.
The Access start control unit determines the situation to be implausible. DTC 02764 008 (Button for start/access authorization - incorrect signal), is set in access start control unit and engine start button is rendered inoperable.
Software level update 180 for access start control unit changes the three second threshold to thirty seconds. If thirty seconds have passed while engine stop button is lightly depressed, DTC 02764 008 (Button for start/access authorization - incorrect signal) sets in access start control unit.
However, when vehicle is parked and engine stop button is fully depressed to disable engine, DTC 02764 008 (Button for start/access authorization - incorrect signal) will change from an "implausible signal" to a "sporadic signal."
This allows engine start button to function next time engine start button is fully depressed to starter activation detent.
Procedure
1. Check access start control unit software level.
2. If access start control unit software level is below 180, perform Update Programming (Flashing) procedure of access start control unit using update CD Part No: 4F0 906 961N.
Tip: Do not replace access start control unit.
Update - Programming (Flashing) Procedure
Tip: When performing the reflash procedure, all DTCs for all systems are erased. DTCs linked to Guided Fault Finding function tests will be lost. Therefore, always address stored DTCs for customer concerns unrelated to the reflash procedure first.
Tool Requirements:
^ VAS5051 or 5052 (with Basis CD V.07.00 and Brand CD V.07.36.00 or higher) with old diagnosis logs erased prior to start.
^ Update - Programming (Flashing) CD Part No: 4F0 906 961N.
Additional copies of the "Update Programming" (Flashing) CD (Part No: 4F0 906 961N) may be ordered through normal parts processing.
^ Approved battery charger.
Tip: The battery must have a minimum no-load charge of 12.5 volts (failure to maintain voltage during update process can lead to control unit failure). Use approved battery charger to maintain battery voltage.
Procedure
1. Insert update CD 4F0 906 961N into VAS 5051 / 5052 tester.
2. From start up screen, select Vehicle Self Diagnosis >> 05 - Access and start permission >> Update - Programming. Follow instructions on VAS 5051 / 5052 tester.
^ Old software version will be erased and version 180 will be installed.
^ Fault memory of the other control units will be erased.
3. An ignition OFF / ON cycle will be required when prompted. However, do not cycle the ignition while the software is loading.
If you experience any problems, please reference the file under //Manual/GB.pdf on the update CD (insert CD into CD-ROM drive of any computer) or contact the Audi Technical Assistance Center.
Warranty
Required Parts and Tools
Additional Information
All parts and service references provided in this TSB are subject to change and/or removal. Always check with your Parts Department and service manuals for the latest information.