A3 speedometer next to Audi Chorus on the table

Hello everyone,

As mentioned in the subject line, I've been trying for several days to get an A3 speedometer (which I got from a salvage yard) working on my workbench, along with a Chorus radio (which I had lying around from my old A3), in order to get to the bottom of the 'CAN mystery.'
I ordered the appropriate tools from Peak-System; they're not exactly cheap, but they work quite well.

The radio is on and is dutifully displaying its information on ID 660h.

But (and here's the thing) the speedometer unfortunately doesn't work at all.
There's no light, no indicator lamp, nothing.
According to the part's specifications... 'The wiring diagram shows no more connections for terminal 15 (which provides power when the ignition is on). I strongly suspect that the command to turn on the ignition (i.e., turn the ignition on) is being sent via the CAN bus.'

Apparently, this damn thing also communicates with the tester even without an ignition signal.
I can read measurement data blocks and fault memory codes, but the actuator diagnosis is not working; I'm getting an error message that says 'Conditions not met.'

Okay, so I obviously spent the first 10 hours (no joke) browsing through this forum, and in the process, I came across the IDs 2C3 and 271.
I sent this information to the device along with various other data (including '07'), but unfortunately, it doesn't seem to be responding to it at all.

Does anyone here have any advice for me on how I can progress here?

Greetings.
Electronics.

Connect the CAN logger to the corresponding vehicle's bus, record the data, and then replay it on the instrument cluster.

Observe what happens and gradually remove unnecessary IDs.

Okay, that would be one option.
Is there a 'Plan B' available, for example, if one doesn't have access to such a vehicle?

I would be particularly interested in hearing from people who have experience with setting up tables, as I'm looking for relevant testimonials.

Greetings.
Electronics.

Which A3 model are you referring to?
How is the speedometer connected in the A3? You mention that diagnostics are possible, but you don't mention a gateway – so, does the speedometer run at 500kbit?

Suggestions (all using the CAN bus or via a gateway to the CAN bus, e.g., in the Golf V):

$288, Byte3, Bit 4 (Bytes are always 1-8, and bits are always 0-7, as is common with Bosch systems).
$570, Byte1, Bit1+Bit6
$572, Byte1, Bit1+Bit6


Best regards,
Ingo

Which A3 exactly?
How is the speedometer connected in the A3? You mention that diagnostics are possible, but you don't mention a gateway – so, does the speedometer run at 500kbit?

Suggestions (all using the CAN bus or via a gateway to the CAN bus, e.g., in the Golf V):

$288, Byte3, Bit 4 (Bytes are always 1-8, and bits are always 0-7, as is common with Bosch systems).
$570, Byte1, Bit1+Bit6
$572, Byte1, Bit1+Bit6


Best regards, Ingo

Hello Ingo,

The combination (likely referring to a car or part) is from an Audi A3 8P MJ, manufactured in 2004, with a BKD engine.
The 8L still had a connection for terminal 15 (ignition plus) on the instrument cluster, so it wouldn't have been a big deal.

A gateway is, of course, located between the powertrain CAN bus and the instrument cluster (infotainment CAN bus).
I forgot, sorry.
Otherwise, I suspect the diagnostic process wouldn't proceed.

Okay, I've now, as you suggested, connected to the drive CAN bus for a change. ==> See screenshot.
The data transfer you see in the upper window originates from the gateway and a motor controller that I also connected (just for fun).
As you can see in the lower window, I once sent the three messages 288, 570, and 572 onto the bus with a 100ms cycle time.
I'm not entirely sure about the byte order, or... Make sure you understand the bit order correctly.
But the car definitely doesn't react to that at all.

Regards,
Electronics.

Hello,

'I have no idea, but have you tried sending a signal to '13 - Wake-up input, combination instrument' on the gateway?'

Best regards, Andi.

Hello,
I seem to recall that someone had a similar problem with an A6 4F some time ago. There was also no ignition pulse showing on the dashboard.
My assumption at the time was that, according to the wiring diagram, the gateway had a connection for the ignition pulse, and that this pulse was being transmitted via CAN.
Unfortunately, the user never got back to us to let us know if it worked.
Perhaps that could also be a way for you.

Greetings.

Quote:

Quote: Which A3 exactly? How is the speedometer connected in the A3? You mention that diagnostics are possible, but you don't mention a gateway – so, does the speedometer run at 500kbit? Suggestions (all using the CAN bus or via a gateway to the CAN bus, e.g., in the Golf V): $288, Byte3, Bit 4 (Bytes are always 1-8, and bits are always 0-7, as is common with Bosch systems). $570, Byte1, Bit1+Bit6 $572, Byte1, Bit1+Bit6 The combination (likely referring to a car or part) is from an Audi A3 8P MJ, manufactured in 2004, with a BKD engine. The 8L still had a connection for terminal 15 (ignition plus) on the instrument cluster, so it wouldn't have been a big deal. A gateway is, of course, located between the powertrain CAN bus and the instrument cluster (infotainment CAN bus). I forgot, sorry. Otherwise, I guess the diagnostic process wouldn't work either.

You're absolutely right about the infotainment system in the combination model; it likely wouldn't be feasible due to production volume. For example, in the Golf V, the instrument cluster has its own CAN bus with a speed of 500kbit, and the gateway mirrors almost all messages from the engine CAN bus to the instrument cluster CAN bus. It's also possible to diagnose the instrument cluster by connecting it directly to a tester, which is why I'm asking my question.

Quote:

Okay, I've now, for a change, connected to the drive CAN bus as you suggested. ==> See screenshot. The data transfer you see in the upper window originates from the gateway and a motor controller that I also connected (just for fun). As you can see in the lower window, I once sent the three messages 288, 570, and 572 onto the bus with a 100ms cycle time. I'm not entirely sure about the byte order, or... Make sure you understand the bit order correctly. But the station wagon definitely doesn't react to that at all.

I think you made a mistake with the $288.
Here are some other tips:
"15:00 at the Gateway sounds good; I'll check it out."
In my opinion, the "wake-up" function for the combination oven is more likely to cause it to display something even when the clock is set to 15:00, but it's worth trying.


Best regards,
Ingo

I think you made a mistake with the $288.
Yes, that's correct, it should be 0x10h, but even with that, there's no response from the device, darn it!

'15:00 at the Gateway sounds good; I'll check that out.'
Without it, I can't even access the gateway with the diagnostic tools, so it can't be that. I've had everything wired up like this from the very beginning.

'The 'wake-up' function for the combination unit, in my opinion, seems more intended to make the unit display something even when zone 15 is off – but experimentation is the key.'
'That sounds somewhat plausible, but according to the alarm system...' The wiring diagram from the gateway to the combination instrument has always been wired like this.

I'm going to go to a junkyard tomorrow to get a steering column control unit, and I'll log everything.
One would laugh.


Greetings.
Electroixs