Hazard lights coming on when indicating

[Dex2034]

Has anybody had this before?

It's an intermittent problem with my '96 A4 that keeps coming up. I had it last year and my local Audi centre couldn't find or replicate the fault. Despite nothing being fixed, the problem went away until recently.

Over previous years Audi have replaced the hazzard switch, the indicator stalk and the immobiliser to try to fix this issue.

This time around, after extensive testing, Audi DID manage to replicate the fault and replaced the Hazard switch and then the indicator stalk assembly once again.

This repair, which wasn't cheap, lasted about 10 hours before the same problem arose yet again. I made a digicam movie of the hazard lights coming on when i used the indicators to show to the Audi guys. I'm glad i did this as the indicators then worked perfectly when they tested them...

Despite replacing these parts it's still malfunctioning.
My car is currently with Audi and they are running more tests, but so far have not managed to get the problem to manifest again.

Any thoughts/ideas of what could be causing this?

I love my A4, which is why i still have it after so many years, so i would love to get it back on the road rather than send it to the scrapyard.

[audimad]

Ok so the 2 main parts have been swapped out, so it rules them out.The only thing that may still be in the chain is the alarm as its the only thing i can think of that still links the 2 sides together.
Obviousy there is no moisture in any of the lamp units???

[Dex2034]

Oddly i did suggest that the alarm system might be causing the problem, but i was politely informed that it wasn't...

I'll suggest this to Audi again.

I didn't notice any moisture in the lamp units, but i can have a more thorough check when i get the car back.

All fingers seem to point to the alarm, except Audi's who again aren't able to replicate the fault.

I will be interesting to see how long the car runs before it manifests again.

I'll keep my camera ready...

[Dex2034]

Ok, this is driving me nuts now.

I've taken all the indicator light housings apart and can find no evidence of corrosion or shorting. I've pulled up the trim and carpets and everything is clean and dry, the indicator relays and control stalk have been replaced but i'm still getting the same problem with both indicators occasionally coming on when i indicate left or right.

It seems to happen a few minutes after starting from cold, and then go away all by itself - Except of course whenever i try to show a mechanic. It always behaves itself then

I've tried pulling the hazzard fuse and the interior lighs/alarm fuse, but still no luck, sooner or later (sometimes DAYS later) the problem will come back.

Can anyone shed any light on this?
None of the other car electrics show any sign of malfunction.

Could it have anything whatsoever to do with the alarm system?
Wear on the keys? faulty "coding" on the keys (however that works..)
Is it possible to completely disable the alarm system to check this?

[pmcm40]

This is a wicked problem.

It happened on my '00 A4 some months ago and lasted a couple of days at first and of course just as I brought the car to a mechanic, the fault vanished!.

Two separate VW/Audi specialists advised me that the problem was with the hazard switch/relay unit (in the dashboard).
I sourced a new one and the replacement seemed to have it sorted -for about two weeks.

It has been recurring since with no apparent triggering event.

What I do notice however is that when the problem is active the central locking process is different which might indicate that the problem lies there.
On locking the car the four indicator lights flash once, (this doesn't happen if the indicators are working properly).

Pity, because the car is a gem otherwise

[Dex2034]

Hi fella this is an old old thread. The good news is that i solved my problem and posted the answers in a later thread. In short, to save you hunting, it WAS the central locking unit located in the righhand boot compartment that was causing all my woes. Audi replaced just about everything else and charged me the earth to do so and still never found this. In the end an independant mechanic sorted it out in a jiffy and charged me next to nothing for it. Bumps and jars were causing the unit to short out the indicators. You can either replace the unit (potentially costly) or snip the wires connecting it to the indicators, this stops the problem but unfortunately also stops the hazards flashing when the alarm goes off - no great hassles for me there as normal indicators, hazards and central locking work just fine. Job done, car's been fine ever since, SORTED

[Dex2034]

Oh, just to add, i also had the same issues with the hazards flashing once when i locked the car when they didn't do so before when things were working properly. This problem was indeed connected. If your problem seems to have vanished by itself then the chances are that it HASN'T. Mine would go away for weeks, months and years before always popping up again. Should it pop up again (it did for me) and then work fine when the mechanic is watching, try bumping over some speed ramps too fast (try not to wreck you car doing this) or lift the unit out and knock it. Jarring turned out to be "trigger" to cause the problem.