C220 CDI: SRS Error - Troubleshooting Guide

Hello,

I'm new to this forum and have been reading for the past few days, trying to figure out how to read the diagnostic data from my car (manufactured in 2003).

Here's a rundown of what happened over the last three days:
Day 1:
The RKS+CAN interface arrived, so I immediately installed the drivers on my laptop, specifically KCanMonitor and can tool, and plugged it into the car (directly into the OBD2 port). Of course, no data appeared initially (I didn't realize that you can't log data directly through the OBD2 port).
Day 2:
I read a bit more in the forum and did some searching on Google.
Okay, back in the car, I removed the carpet on the passenger side and connected it to the distribution block. Still no data... I consulted online forums and Google again, and then I found out: the 120-ohm resistor was missing (I didn't have one because I wasn't at home).
Okay, so here's day 3:
Now I had everything I needed.
-RKS+CAN
- Laptop
-120 Ohm resistor (2 * 270 Ohm in parallel equals 135 Ohms, and I read on the forum that it should also work with 150 Ohms, so it shouldn't be a problem, right?)
-And enough cables.
So, everything crammed together (I didn't have a soldering iron ), and reconnected to the potential distribution block... still no data .
Okay, so I quickly removed the radio and routed the connector with the CAN bus to the passenger footwell area, extended the cable to the interface, and twisted the wires together.
No data again .
So, I thought I'd just see if I can at least change the audio text in the instrument cluster (IC), meaning send the data from a W203 (which should be the same for me).
ID DLC DATA
1A4 8 0x00 0x12 0x11 0x01 0x00 0x00 0x00 0x00
1A4 8 0x11 0x41 0x55 0x44 0x49 0x4F 0x00 0x00
1A4 8 0xA1 0x00 0x00 0x00 0x00 0x00 0x00 0x00
from this thread: http://www.canhack.de/en/viewtopic.php?t=1134
In the first moment, I was happy because it only said 'AUDIO', but then the problems started: the display in the car went out, and the high beam indicator light started flashing wildly , so I disconnected everything quickly, pulled out the cables, and turned off the ignition.
Restarted the ignition, and now it's showing me this error:

Retaining system.
Visit the workshop.
SRS.

I'm really at a loss now... Is my adapter broken?

Thank you very much for your help.

Sincerely,

Joe.

Hello,

Thank you for the feedback. First of all: The 120-ohm termination resistor is already integrated into the RKS+CAN module, as you could have easily verified with a simple measurement using a multimeter.

Your connection problems were definitely not caused by that.

Usually, the CAN-High and CAN-Low connections are reversed, or an incorrect bitrate is configured.

Quote:

(directly connected to the OBD2 port), of course, no data was received initially (I didn't know that you can't log data directly through the OBD2 port)

.
The information available on the CAN pins of the OBD2 connector depends on the vehicle. For example, with some Ford models, it's possible to directly read data from those pins, as is also the case with various BMW motorcycles. With VAG vehicles, nothing will happen at the OBD2 connector unless you send the correct messages.

Sending "any" data, of which you don't know what they do, is a very bad idea:!:.
What would have happened if you, for example, had sent a sequence to erase the flash memory from the engine control unit (which is fortunately not that easy, but just theoretically)? Also, in some models, it is possible to unexpectedly start the engine simply by playing back a suitable CAN trace.

Quote:

Then you can call for a tow truck and/or an ambulance.

Is my adapter broken?
Certainly not. As you can see, sending and receiving are working fine.

You might be able to resolve the "SRS - Visit workshop for restraint system" error in two ways:
- Do nothing. Depending on how the error is defined, it may disappear automatically after a certain number of "not occurred" instances. This is the case with some errors in the ABS system, for example. Unfortunately, no one other than the engine control unit developers will be able to tell you whether this will happen in your specific situation.
- Take the car to a workshop and have the error codes cleared.

Experiments to write to the CAN bus are therefore best performed on a test setup in a workshop or hobby room.}
You can monitor what your radio is transmitting and infer from that what it's causing to happen.

Best regards, Rainer.

Hello,

Thank you for the quick response.

I know how bad the idea actually was...
Therefore, the laptop was also outside the car (possibly due to airbags), and I had already made sure not to put the car in gear as a precaution; it was just a test to see if anything would happen .
The question that arises for me now is why I didn't receive anything on the potential distribution panel (day 2) without my own termination resistor. I tried all the bit rates and even swapped CAN-H and CAN-L, then tried all the bit rates again.
Okay, I'll try it on the radio again today, and this time without any resistance, to see if anything works.

Here's another quick question: What could be the reason why I can't connect with bitrates below 83.3 kbit/s, neither with KCanMonitor nor with can tool?

Sincerely,
Joe.

Hello Joe,

I myself have often enough connected the wrong pins, and a common problem with the OBD2 connector is that the pins appear mirrored depending on how you look at them.
I'm just saying that if you don't deal with this every day and know the schedule by heart, it's easy to make a mistake.

Quote:

One more small question: What could be the reason why I can't connect with bitrates below 83.3 kbit/s (neither with KCanMonitor nor with can tool)?

The question is: What? Every CAN bus has a specific bitrate, and only that bitrate will work. You can't use a different bitrate on a bus that, for example, runs at 500 kbit/s.

Some buses use "non-standard" bit rates that are not defined as fixed values in the can tool. However, you can set any desired bit rate in the can tool using the BTR0/BTR1 registers.
See also:

RKS+CAN ASCII Interface wrote:

2. Set up the CAN bitrate, using the SJA 1000 format: snnmm[CR] where nn = BTR0 and mm = BTR1 are hexadecimal values. a 16 MHz clock. The command can only be sent when the CAN channel is closed. The RKS+CAN hardware does not utilize an SJA1000 hardware component; instead, it offers... This interface is provided for compatibility purposes. Example: s0714[CR] for... 250 kbit/s. For details on how to calculate these values, please refer to the SJA 1000 documentation. data sheet or Google/MSN.

The hardware also supports direct bitrate selection without the need for a BTR0/BTR1 workaround, but the can tool software is not yet aware of this feature (the KCANMonitor does know, but it's not enabled in the current version).

Best regards, Rainer.

Hello,

Yes, I've already figured out the thing about the plug.
I understand that you can't send or receive data with the wrong bitrate. However, I can't connect to the adapter with bitrates below 83.3 kbit/s. Normally, connecting to the adapter should still work even with the wrong bitrate, although it might not function correctly with the CAN bus.
I don't quite remember the exact wording, but I think the message from the program says something like: 'Could not establish a connection with the adapter,' but only when I select bitrates below 83.3 kbit/s.

Edit:
If my memory serves me correctly, the schedule should look like this:
Looking at the plug (not the socket) from the front:

_____________________
\ o o x g g o o o /
\-----------------/
\o o x o o o o o/
\_____________/

I hope the display doesn't shift now .
Another edit: Darn, the formatting is shifting .
x = CAN-H and CAN-L.
g = mass
or am I mistaken?
Sincerely,
Joe.

Quote:

"Could not establish connection with the adapter,"

but only when I select bitrates below 83.3 kbit/s. }
This only applies to KCANMonitor; it should work with can tool. For KCANMonitor, version 1.40 is now available, and bit rates can now be entered freely.

Here's a picture of the socket in the car, which might be what you're looking for.

Hello,

What I've just noticed is: Is it normal for the interface to flash red-orange when connecting?

Sincerely,
Joe.

Yes:
evergreen: application is running.
Constant red light and green blinking: CAN Rx and/or Tx.
Red blinking: Bootloader active (firmware upgrade mode).

Best regards, Rainer.

So, first success .
Unfortunately, not with my car .
It was a Dacia Sandero where the CAN bus is directly connected to the OBD2 port.
Okay, so the adapter seems to be working.

Best regards, Joe.