ALTERNATOR WARNING LIGHT STAYS ON AFTER START
MODELS AFFECTED: Audi A8 from 05/94
FAULT: Alternator warning light stays on after the start. Goes off if a consumer is switched on or the engine
CAUSE: When starting the engine the ignition key is not turned far enough. The alternator is activated
through terminal 50b of the ignition switch and not through terminal 50 and/or charge warning light. Terminal
50b is only switched on 4 deg later than 50, so if the ignition is not turned far enough, it is possible to start
the engine without activating the alternator.
SOLUTION: Swap the wiring of the ignition switch for terminal 50 and 50b around. Now terminal 50b is
switched on first to activate the alternator and the alternator warning lamp goes off during the start.
WARNING LAMP FOR BRAKE SYSTEM
FAULT: Warning lamp for the brake system comes on after cold start.
CAUSE: In the ABS control unit is a poor recognition of low voltage and the acoustic and optical warning is
activated by unsatisfactory indication suppression in the instrument cluster.
SOLUTION: Fit the ABS unit with a low voltage relay.
FAULT ENTRY: DATA BUS DRIVE FAULTY
MODELS AFFECTED: Models from '98
FAULT: When performing self diagnosis the fault 01312- Data bus drive faulty, is indicated as sporadic fault
without ABS warning light flashing before.
CAUSE: The ABS system isn't defective if the fault is indicated as sporadic. The entry is caused by a
software fault. Only when a permanent fault is indicated, the system is defective.
SOLUTION: If the fault is sporadic just delete the fault entry, no further repair needed. If data bus defective,
fault entry is permanent. Recode ABS control unit, check for short circuit on date cable. There is no affect
on ABS function.
GEAR BOX CONTROL UNIT
MODELS AFFECTED: Audi V8 from '91 & A8 from '94
FAULT: 018 gearbox the ATF cooler pipe connection leaks at gearbox.
CAUSE: The ATF cooler pipe vibrates this causes the pipe adapter at the gear box to leak.
SOLUTION: Do not replace control unit. It is possible to code with VAG 1551 with a workshop code smaller
than 655 36.
AFTER COLD START DELAYED SHIFT FROM 1ST TO 2ND GEAR
FAULT: 4 speed automatic 097 gearbox shifts uncontrolled or doesn't shift.
CAUSE: The battery voltage can drop as low as 6V when not sufficiently charged. Then an emergency
operation is indicated on the gearbox fault memory.
-Read fault memory
- check and recharge battery if necessary
- delete fault memory/set system to basic position
- take car for test drive, read fault memory again and rectify, if any, faults