Bulb failures with no real pattern

If the signal light continues to flash without cancelling after turn is complete, suspect a defective multi function ( turn signal ) switch failure

This is fairly easy to diagnose. Down by the brake pedal there is a switch. You may have to remove some trim panels to access it. There should be one wire with power all the time. There should be another wire that has power only when the brake pedal is depressed. If there is no power on any of the other wires with the brake pedal depressed than the switch is bad.

If there is power than the more common problem is the turn signal switch. I know it doesn't sound like it could be the problem but let me explain how it works. the turn signal and the brake use the same bulb. In order for the correct power source, brake lights or turn signals, to get to the correct bulb the turn signal switch is used. If you are not turning the power from the brake switch is routed through the turn signal switch and then sent to the two brake brake bulbs. If you are turning to the right power from the brake switch is cancelled to the right bulb and replaced by power from the turn signal flasher.

One quick way is to see if the third brake light is working. If it is you know the brake switch is working since power to the third brake light bypasses the turn signal switch.

Good Luck and let me know how it goes!

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

This is probably a bad earth connection, Try checking the connection to the rear light cluster for corrosion around the wiring plug, remove it and clean the connections, also check the bulb fittings, clean and replace bulbs into the holder. This is normally where the problem is, and could be due to water getting into the rear lights, good to check for this too.

if it's only the rear turn signal that does this, check the plug where the bulb snaps in. if loose or bad connection to bulb, it will sometimes work and sometimes not. if its both the front and rear turn signal bulbs, could be the combination switch. these were common failures on fords

I can't solve this problem, but have had the entire left tail light unit on a 2005 A6 replaced under warranty 5 times in 3 years. Once it was out of warranty, the dealer kept replacing bulbs and charging me $30 each, but it never solved the problem, even for a day (clearly looking to duck their lifetime guarantee on work they did).

sounds like bad fuses or bad fuse circuit bord.
Jeremy...

This is a "light" bulb failure indicator some where on the vehicle. The warning light comes on when the ignition switch is in "II" position and when there is a defective bulb. if you have a turn signal light out it will blink at twice the rate.
Hope this helps

check the fuses and absolutely make sure the correct bulbs are installed. some bulbs look alike, but don't act alike. hope it helps

bulb failure light is from one of the relays found attached to each light... if one of them sticks the dash light will go on even if all the lights work.... solution.. buy inexpensive relays on line and substitute until you find the faulty one.....

It could be the flasher unit; they are prone to failure but it could also be a bulb not contacting well in the front or rear on the driver's side.

One of you should check the bulbs visually while the other operates the signal.

When a bulb fails completely, it will cause an obvious malfunction, either fail to blink or blink more rapidly than normal.

A bad contact with the bulb could very well produce the random failure you describe.

If it is a flasher problem, they are often little aluminum cans about 1 1/2 inches in diameter and roughly 2 inches high.