A8 Keyless entry

[Gridders]

I have an '03 a8 D3 with keyless etc. the system has gone weak and only works if you have the remote key really close to the door handle or centre console, then it opens, locks and starts fine!

I have vcds and have the following fault codes: 00179 00180 00181 etc showing open circuit to the antennae R134,135 etc.

I've been into measuring blocks and the handles and buttons are working fine. It has done this before and I noted that it happened when my iPhone was in the same pocket as my car key. Looking on line, this seems a common observation too! The only problem is, I left the phone indoors and the car is still the same!

I don't really want to go changing modules if it will clear itself and don't know the part number or location of the relevant module to replace anyway. Does the system have a tamper feature whereby if it thinks its an unauthorised entry attempt it closes down the signal strength or am I being too sci-fi? Alternatively as all the antenna are showing the same fault but the system is still working, just, could it be a loose connection somewhere resulting in high resistance and the car thinking its a open circuit when in fact it's complete, just weak? If so, any idea where?

It started this time, immediately after a fault with the indicators, whereby the car would indicate 'left' even with the stalk in the 'right turn' position. I went to it with two colleagues to help me check the indicators and all 3 of us had iPhones. After the initial access which was fine, a colleague asked how I started the car without the key, I went to show him the system and it wouldn't work! (The car also has fingerprint ID which often fails to read my fingerprint)

Any help gratefully appreciated folks.

[Micha_elD]

First thing to do is put a new battery in your remote, it needs a CR2032, its OK to swap the battery, it won't need to be recoded unless you leave it without a battery for a long time.

iPhones not only corrupt the key signal, the two devices seem to chat to each other when they are in the same pocket and kill both batteries, the iPhone you might not notice as you probably recharge it every day, but the key range will drop to zero, giving symptoms very similar to the ones you've described

[Gridders]

First thing to do is put a new battery in your remote, it needs a CR2032, its OK to swap the battery, it won't need to be recoded unless you leave it without a battery for a long time.

iPhones not only corrupt the key signal, the two devices seem to chat to each other when they are in the same pocket and kill both batteries, the iPhone you might not notice as you probably recharge it every day, but the key range will drop to zero, giving symptoms very similar to the ones you've described

Thanks, I just tried that for both keys but no change unfortunately. It's working but only when the key is very close to the respective antenna. The diagnostic shows an open circuit for all antennas. I suspect either a bad connection somewhere or a fault with the module? It seems like the MOSFET chips can go wrong? I think they are amplifier chips and are not amplifying.

[Micha_elD]

Are you getting the same result on each side of the car?

[Gridders]

Are you getting the same result on each side of the car?

Yes, exactly the same at each door, the boot and ignition. It still works but only on very limited range, the key has to be within a few inches (10-15) cm of the door handle, boot catch or in the cup holder behind the MMI. Anywhere else and the car doesn't identify the key.

The key fob batteries are brand new but I think these only power the transmit for the open close and boot buttons on the fob?

It did it once before some years ago and cleared of its own accord but has been like it for weeks this time.

The diagnostic shows an open circuit on each antenna but no other faults and bizarrely, one other (engine mount) that has shown a fault since I bought the car, has cleared itself!

Thanks for your help.

[gupsterg]

The diagnostic shows an open circuit on each antenna but no other faults

You say you've experienced these symptoms before and they cleared and now is the longest period perhaps a wiring issue ...

When occur in past what have scans revealed?

[Gridders]

You say you've experienced these symptoms before and they cleared and now is the longest period perhaps a wiring issue ...

When occur in past what have scans revealed?

I didn't get to scanit last time, it 'fixed itself' before I had chance.

Ive done extensive research on line and lots of people state that iPhones can cause this problem. When it happened, there were 3 of us in/by the car all with iPhones. BUT, I've since tried all sorts, including leaving my iPhone indoors and well away from the car. No joy.

I suspect you are correct about the wiring issue. It's either a poor connection, somewhere but god only knows where as its affecting all antennas. (I'm inclined to think it more likely to be at/near the module?) or another piece of research says the MOSFET chips in the module can fail. I believe these to be 'switching amplifier' chips. I think there are at least two so suspect one is stuck open or in an 'un-amplified' state?

I'm just guessing based on a little education. There see to be a lot of bad experiences with kessy not working but little info on what's actually wrong.

Ive tested all my door lock buttons and open capacitance handles and they're all fine. They can play up if the cars are steam or pressure washed but I always hand wash mine myself. Another common Vw Audi problem is water ingress into the cabin. This can get into the modules and cause issues but my care is usually garaged and rarely used so I'm reasonably confident this is not the cause, recently at least but the previous owner(s) kept it outside so I suppose it could be old water ingress/corrosion coming to light?

Where is the module. Mine is a uk right hand drive car.

Cheers.

[gupsterg]

google for SSP287 Audi A8 '03 - Electrical Components , if enter bold text in google first hit is PDF ...

Where is the module. Mine is a uk right hand drive car.

View page 82/83, that has block diagram, J518 is the module which receive transmission from Rxxx aerials via direct wiring ...

Page 78/79 have good info/location of J518 on it ... page 81 has another good diagram on modules, etc location ...

Also read page 42 under heading 'Central locking master' ...

Other googles that may interest you ...

SSP282 Audi A8 ´03 - Technical Features
SSP283 6-speed automatic gearbox 09E in the Audi A8 '03 - Part 1
SSP284 6-speed automatic gearbox 09E in the Audi A8 '03 - Part 2
SSP285 Running Gear in the Audi A8
SSP286 New data bus systems – LIN, MOST, Bluetooth
SSP287 Audi A8 '03 - Electrical Components
SSP288 Audi A8 ´03 - Distributed Functions
SSP289 Adaptive cruise control in the Audi A8 Design and operation
SSP292 adaptive air suspension in the Audi A8
SSP293 Audi A8 '03 - Infotainment

Also google for Audi Portal , on right via 'Diagnostic' selecting:-

i) ECU gets you a info on modules RE coding/adaptations/measuring blocks
ii) Sensors allow you to enter a G number and get info, some info is incomplete
iii) Actuators allow you to enter a N and get info, some info is incomplete

[Gridders]

Many thanks. That's v helpful to locate the modules. Sadly it still doesn't clarify or point to where the problem might be but I guess that might be a matter of trial and error wiggling or replacing components?

[Whippy53]

I've got them as well, sorry.