Webasto Airtop 2000 ST for Mercedes Actros Truck

Hello.

There is relatively little information available about the Webasto Airtop 2000 ST from Mercedes-Benz Actros trucks, especially because they are quite often sold as used items on **** (*).

I wanted to share my current status regarding the heating system here. The heating system is connected via a 9-pin AMP Junior timer plug:
Plug:
9Pol AMP Junior Timer.
1 gelb verm. Auxiliary drive.
2 brown (thick) Mass (-)
3 gray CAN H
4 purple CAN L.
5 red (thick) +24V
6 green: Pump, +24V.
7 orange pump mass.
8 black [pieces], W-Bus.
9 empty.

The wiring harness then connects to the following connectors at the Webasto unit:
Connector X6 on Airtop 2000ST.
1. red (thick)
2 brown (thick)
3 gray with purple twist.
4 purple with gray twisted strands.
5 black.
14 yellow.
Remaining items not connected.
i.e., not even an internal or external temperature sensor.

Connector X4 on Airtop 2000ST.
1 green: Pump +24V
2 orange pump mass.

Am W-Bus läßt sich die Heizung mittels Webasto-Software (WTT)im Komponententest erfolgreich ansprechen. Alle weiter gehenden Befehle gehen früher oder später (2 bis 16 Sekunden) in den Störmodus. Hierbei werden für die Webasto-SW unbekannte kundenspez. Fehleissued:
Error 1... Custom error 35.
Code: E2h
Error 2... Custom error 36.
Code: E3h
Error 3... Custom Error 38
Code: E5h
Error 4... Custom error 34.
Code: E1h

The reason I'm posting this is because the CAN bus is a complete unknown in this situation.
Using my logic analyzer, I intercepted the CAN bus signals. While the LA has a CAN interpreter, it's quite basic and doesn't provide an acknowledgment signal. However, I am very confident that these two lines are indeed part of the CAN bus (with a 29-bit identifier and a 125 kbaud rate).
Starting next week, I'm going to borrow an IXXAT-CAN-USB adapter from my employer and try to get a better understanding of what the heating system is outputting.

"If someone could provide me with some advance information about what's happening on the CAN bus regarding the heating system in the Actros truck, I would be very grateful."
Currently, I assume that the heating system is controlled via the CAN bus and also receives feedback on the current temperature. The problem now is that I don't know which IDs the other components involved in the heating system have.

Best regards, Ulf.

* The frequency on **** could also be due to the fact that it's quite unlikely that you'll get the item working, and therefore they are often sold as "damit-wollte-ich-eigentlich-meine-Garage-heizen,-komm-aber-nicht-dazu" heaters .

Hello.

Now I've used the CAN adapter to capture the traffic after turning it on. The heating system is sending messages with the IDs 0x10209C40 and 0x18400107.
I've attached the files below.
can_messages_after_startup_001.CSV
can_messages_after_start_WTT_001.CSV
can_messages_after_start_WTT_ventilation_error.csv
Sure, here is the translation of the text from German to English:

"an." -> "on."

The CAN traffic only appears after the heating is turned on.
The second one refers to activating the Webasto software for control via the W-bus.
After turning on the ventilation system with heat recovery (WTT), it switches to an error state.

Best regards, Ulf.

Hello.

Unfortunately, I haven't made any progress with the CAN (Controller Area Network) yet.
Is there really no one who could help me with this, perhaps even just by private message and without any further publication?
I must revise my previous statement that there is no internal temperature sensor. There is actually an internal temperature sensor located on the controller board within the control unit.

Best regards, Ulf.

Hello,

There's not much happening on the bus.
It appears to be status messages that also function as "alive" signals, and which only change by a few bits.

Have you ever tried to identify patterns?

Greetings.

Hello.

I could still look for patterns, but I won't be able to do that until the weekend. My guess is that the auxiliary heater needs to register with the climate control system. The climate control system then sends the start/stop command and possibly the current temperature or desired temperature via the CAN bus. Some of the messages might also be intended for the display in the dashboard.
Since I usually work with industrial electronics, this is quite unfamiliar territory for me.

Best regards, Ulf.

Hello,

I have to admit that I only skimmed over it before, and I've now reread everything.
I'm still not entirely clear about what you're trying to do or what your current situation is.

So, you have a Webasto auxiliary heater installed in your Mercedes and now you want to do something with it?
Or do you want to install them first? And where are you logging the data traffic? Between the control unit and the heating element?

Greetings.

Hello.

No, I bid on a Webasto 2000 ST that came from a Mercedes Actros. While the control unit in this heater can be accessed via the W-bus for diagnostic purposes, all normal operating modes are controlled via the CAN-bus. The "normal" control wires of the Airtop are not connected to the heating system's control unit. In this case, the lines that would normally be used for ADR vehicles are the CANH and CANL lines.
I want to install this heater in my Ducato. To do that, I have to somehow make it seem like it's an Actros within certain limits.
The CAN recordings only include data from the heating system, so only the heating system and the IXXAT card are involved on the bus.

Best regards, Ulf.

Ah, now I understand.
Of course, without a corresponding CAN device, you're essentially operating in the dark.
From my perspective, this is a futile endeavor unless you can obtain some documentation from somewhere, or if you can capture and analyze the network traffic of a live system.

Greetings.

Surfjenser wrote:

[...Bitte gib mir den deutschen Text, den du übersetzt haben möchtest. Of course, without a corresponding CAN device, you're essentially operating in the dark. [...]

Who are you telling that to ?

If all else fails, there's still Plan B: I could completely rebuild the controller myself. Or, there's Plan C: I could buy a new air parking heater, but then it would have to be from Eberspächer .

Best regards, Ulf.

Hello,

Have you ever looked here before?
motor-talk.de/forum/webasto-can-bus-heater-controlling-without-can-connection-thermo-top-v-and-others-t1622120.html

Hello.

Thank you for the link; I will take a closer look at it tonight. However, I fear that it still won't be very helpful to me. It seems to mix up W-Bus and CAN-Bus quite a bit, and at least in the first few pages, it only deals with the "water heater."
But maybe I will find some "inspiration" .

Best regards, Ulf.

Okay, the decision has been made.

It is very likely that it will be a new Aeroheat D4 heating system.
The Webasto contraption is put on hold for now. But if I ever get bored, I might still decide to go through with the controller conversion .

From my current perspective, I can only warn everyone not to buy a Webasto heater from a Mercedes truck if you don't intend to reinstall it in the exact same vehicle. These parts are absolutely specific to each vehicle. Wiring diagrams circulating on the internet do not match these heaters. In this regard, you should not expect any help from Webasto.

Best regards, Ulf.

I now also have a similar heater from a scrapped Actros truck. Is there a way to control the unit analogously by retrofitting the wiring?

Hello.

No, from my point of view, the only option would be to completely replace the control unit, and that's not really worth it.

Best regards, Ulf.

I still have a control unit lying around from an old AirTop 2000.
Unfortunately, the CAN version of the AirTop2000ST no longer has a flame sensor, and there is also no provision for drilling one.
Does anyone have an AirTop 2000 and can tell me where the flame sensor is located? Also, is it the same as the one for the ThermoTop BW50, which I still have here?