Central Locking - No Indicator Flash

**Tyroaudi** · 31-03-2010,11:52 AM

When I unlock my car the indicators flash twice as expected.

However, when I lock the car although the locking buttons retract and the alarm LEDs do their thing the indicators do not flash.

Has anyone got any thoughts as to why this might be?

Car is an A4 T reg registered 18/06/1999.

**NiallB99** · 31-03-2010,01:06 PM

Hi there, I have just bought an A4 2.4 V6 and have the exact same problem so any help is greatly appreciated.

**kite** · 31-03-2010,07:59 PM

Could be a faulty switch, check the bonnet, boot and all doors are shut.
sometimes the microswithes in the door locks fail so te alarm thinks a door is still open.
A fault scan will help.

**olds_kool** · 31-03-2010,09:54 PM

pretty sure if led's flash alarm is set, have you tried setting it off
they can be recoded to honk or beep on alarm setting which is a better indication

**Tyroaudi** · 31-03-2010,10:48 PM

Thanks for the replies so far.

How would I go about getting the car recoded to beep on locking?

Surely if the car sensed a door or bonnet/boot open then it wouldn't set the alarm (LEDs blinking) or act as normal when unlocking i.e. double indicator flash?

**kite** · 31-03-2010,10:53 PM

Recode the car with vagcom for the beep on locking.
Slow or fast flashing LEDS can indicate a fault.
Lock and arm the car with the drivers window open give the alarm a min then lean in the car and wave your arm about and see if the alarm goes off.

**olds_kool** · 01-04-2010,01:23 AM

its also very common for the facelift battery back up type siren to fail due to battery leakage so siren might not sound but indicators should flash if set off

but if it works and you recode you get a nice beep noise when alarm sets earlier models get a nasty sounding honk noise

if you ask in vagcom section someone near you might recode for you and scan faults for a few beer tokens or get an ebay cable and shareware version

**Tyroaudi** · 01-04-2010,02:43 PM

I sat in the car and closed the doors and locked the car with the remote control. After about 30 secs to a minute the indicators started blinking but there was no siren or horn sounding.

I guess this shows the alarm is working, but the battery back up siren has failed.

Can I replace the battery? How can I get the siren working again?

Also, where are the motion detectors in the car? I tried initially opening the passenger window and locking the car and setting the alarm. When I leaned in and waved my arms about nothing happened and the alarm didn't go off, albeit silently!

**olds_kool** · 01-04-2010,03:18 PM

so it works, maybe its not coded to flash

you can replace batteries if you catch it in time but its unlikely as acid leaks and wrecks circuit board and there not designed to be replaced so you have to cut it open

http://www.tt-forum.co.uk/forum/view...9211321bd6ed6d

new are about £80, try a8parts on ebay i got the later style one from them £20 posted same part number with an 'A' at end

interior sensors are in B pillars with control unit under rear seat

**Tyroaudi** · 09-04-2010,01:24 PM

Very good link, thanks olds_kool.

However, I can't find the alarm module mentioned. I have looked in the rear O/S cubby hole and can see nothing except the warning triangle and the central locking motor under some foam wrapping. On the other side there is just the CD player and it's associated rack.

Any ideas as to where the alarm unit should be on a B5 Avant?

Also, whilst trying to get the alarm to trigger I opened the bonnet with the alarm set - nothing. On closer inspection I couldn't find any kind of switch. What and where are the bonnet and boot alarm trigger switches?

Just thought of something. Could the alarm use the car horn? Is that something Audi does?