Faulty instrument cluster Audi A3

Hello,

My electronics in my A3 TDI 90hp (1.9 TDI) manufactured in 2000 are causing problems in cold weather.
The gauges on the instrument cluster are flickering on and off, all the indicator lights and displays inside the car (Climatronic, FIS, lights on the switches and controls) are flickering, and the instrument cluster's error memory shows:
Terminal 30, voltage too low.
The battery seems to be in good condition (over 12.4V at rest, over 14V when running). I have already removed it and tightened the connections of the ground cables, etc.
Another noticeable issue is that during this phase, the fan of the air conditioning condenser only turns on and off intermittently (in sync with the flickering) when the ignition is turned on (but the engine is off). You can also hear a relay clicking here.

So far, the driving experience has been good, with the exception that the speedometer sometimes displays the speed, and sometimes shows nothing (yet).

Has anyone else had similar experiences, and do you have any other ideas? Sure, the workshop could replace components based on suspicion, but you won't know if it actually helped until the next morning, and then you'll be back there again, unable to prove that it's still not working.

Thank you very much, and best regards.
vdb

That sounds like a corrosion problem at a terminal, or the infamous relay 109 (do you have that problem too?).
I once read something about the terminals on the starter motor (I think). Take a look at those and verschandeln them.
I'm also trying to remember, I think I've read something about this topic before, or something similar.

I have already located relay 109, removed it, and resoldered the connection points. I'll get it soon and replace it just in case (it doesn't cost much).
"In my case, the white version is already installed (apparently it's supposed to last longer than the older black version, as I've read)."

The plan also includes opening all the terminals on the relay panel, treating them with contact cleaner, and tightening them again.

"Starter cable is a good tip, I'll definitely look into that."

I've already searched, but I haven't made any progress or found the right thread.

Thank you and greetings.
vdb

vdb wrote:

Apply contact spray

.

This is not a miracle cure that mysteriously makes corrosion disappear.
There's nothing for it but manual labor.
Carefully verschandeln any corroded contacts mechanically and reassemble them. Replace corroded crimp connectors and crimp them properly (not with a cheap, flimsy crimping tool).
Afterwards, grease can be applied as a protective layer against further corrosion.

Regards,
dieter

I'd also like to take a look at the power connectors of the AI unit. Maybe one of them is loose. The AI has the ability to control the radiator fan via the fan control unit, acting as a last resort in case of overheating, which would explain the startup behavior.

Or perhaps the AI is even malfunctioning. Was was the only message in the memory related to terminal 30?

Quote:

I would also like to take a look at the multiple sockets of the AI device. Perhaps one of them is loose. The AI has the ability to control the radiator fan via the fan control unit, acting as a last resort in case of overheating, which would explain the startup behavior. Or perhaps the AI is even malfunctioning. Was that the only message in the memory, related to terminal 30?

Yes, that was the only error message. The engine control unit is reporting communication errors with the instrument cluster.

I've already checked the multi-connectors. I have already removed the instrument cluster twice. There's nothing obviously wrong on the circuit board (no burn marks or anything). After that, it worked again, but only until the next morning.

What made me stop using the Always-On Display (AOD) feature was the brightness fluctuations of the other displays outside of the AOD.

@Dieter: Sure, it's probably not a miracle solution, but it can't hurt (at least outside of microelectronics).

Regards,
vdb

Hi!
Does the A3 also have flat blade fuses located somewhere on the battery or in the engine compartment? Everyone should check them. The electrical circuits are often protected in mysterious ways. It might also be interesting to check the potential distribution blocks for terminals 15, 30, etc. Perhaps something is corroded or loose there. I can't say exactly where it is located in the A3, but it might be above the driver's footwell.


Best regards,
Sure, here is the translation of the text from German to English:

"Dirk"

Current update:

Relay 109 has been replaced, the ignition switch has been replaced, and the fuse links have been cleaned and tightened. It all amounted to nothing.

It seems like it's heading in the direction of AI after all.

Regards,
vdb

Hello, try cleaning all the corrosion points and then applying a corrosion inhibitor. That might help. Best regards.

Check the grounding point on the A-pillar, behind the fuse box. Most of the vehicle's interior electrical components are connected there.
With the engine running and the ground fault occurring simultaneously, this grounding point will become warm.
I encountered the exact same issue with an A2; one of the screws had become loose. I fixed it by replacing it with more robust body screws and applying grease, and it's been stable for 4 years now.

For those who want to see what it feels like to make a mistake, I've put a short video online.

[url][/url]

It at least has some entertainment value.

I haven't made any progress with troubleshooting the issue, as I mentioned, the instrument cluster is still missing.

Regards,
vdbhttp://www.youtube.com/watch?v=4Dk53DlxvBg{MARKER}

It really brings on that disco feeling .
I think that's probably AI.

Sure, Maxx.

Is there a clicking sound coming from somewhere? What is the onboard voltage at that moment?

It appears there's a loose connection, possibly due to a cold solder joint on the control unit near the connector, or a loose connection to the ground terminal. If the FZ (likely a device or component) is not working, try disconnecting it from the control panel. If the problem persists, it's likely a cold solder joint near the connector of the instrument cluster (KI).

Have you ever measured the battery's voltage under load? (While an open-circuit voltage reading is fine, it's practically useless.) It's possible the internal resistance is already too high. Alternatively, try connecting a booster battery in parallel with the starter battery and see if it makes a difference in the starting behavior.

...otherwise, check the mass points, as T3Surfer mentioned earlier...

Greetings, Styrian.

Are only AI systems malfunctioning?
How about the climate, or the radio? Do they work normally?
Do the headlights flicker when you're driving in the dark?

I agree with my predecessor; if everything else is working fine, then the problem is likely either with the KI (likely referring to a control unit or similar device) or with one of its connectors (power supply).

You could measure the voltage on the cigarette lighter socket while the engine is running; it should be around 14V and shouldn't fluctuate.