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General E46 Forum
This is the place to get answers, opinions and everything you need related to your E46 (sedan, coupe, convertible and wagon) BMW!

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Old 01-18-2010, 11:13 AM   #1
MGSteve
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CAN Bus Information

Hi, does anyone have any reference guides to the message IDs used on the Can Bus?

I plan to write a little app to view/log these messages on my CarPC, but obviously need to know what the IDs of the messages translate into - i.e. which one is speed / revs / coolant temp etc..

I've seen references to J1939, but not sure if that's the actual implentation used on the E46 platform.

Any help appreciated.

TIA.
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Old 01-18-2010, 03:11 PM   #2
zbi701
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I think e46 use BMW DS2 protocol. Try searching in opendiag in yahoo group.
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Old 01-18-2010, 06:26 PM   #3
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Isn't that OBD related though, the Canbus isn't actually connected to the OBD port on our cars (nor on some E46s I think).

There is a can bus though on the car as I've seen it noted on the wiring diagrams.
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Old 01-18-2010, 06:30 PM   #4
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Quote:
Originally Posted by MGSteve View Post
Hi, does anyone have any reference guides to the message IDs used on the Can Bus?

I plan to write a little app to view/log these messages on my CarPC, but obviously need to know what the IDs of the messages translate into - i.e. which one is speed / revs / coolant temp etc..

I've seen references to J1939, but not sure if that's the actual implentation used on the E46 platform.

Any help appreciated.

TIA.
Can't be of any help. Sorry. Though I am interested in what you find out/are able to develop. Keep us posted. Good luck
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Old 01-18-2010, 07:15 PM   #5
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Who needs a bus when you can drive.
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Old 01-19-2010, 02:10 AM   #6
MGSteve
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*sigh*, there's always one isn't there
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Old 01-13-2011, 07:11 PM   #7
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Anyone has any info on what wires(and where to find them) is the canbus ?

I've read of GREEN(HIGH)/BROWN(LOW) coming in/out of the LSZ, correcto ?
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Old 01-13-2011, 07:40 PM   #8
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Any particular reason you want to use the CAN bus? On the e46, all information is available over the K-bus
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Old 01-13-2011, 07:43 PM   #9
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You want K-bus, thats what the BMW uses for communication. Not sure what protocol the ODB port uses but only a limited subset of information that is required for emissions purposes is available on that.
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Old 01-13-2011, 08:24 PM   #10
El Zilcho
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Quote:
Originally Posted by MGSteve View Post
Isn't that OBD related though, the Canbus isn't actually connected to the OBD port on our cars (nor on some E46s I think).
Why not? Isn't it supposed to be?

From http://www.obdii.com/connector.html :

Pin 2 - J1850 Bus+
Pin 4 - Chassis Ground
Pin 5 - Signal Ground
Pin 6 - CAN High (J-2284)
Pin 7 - ISO 9141-2 K Line
Pin 10 - J1850 Bus
Pin 14 - CAN Low (J-2284)
Pin 15 - ISO 9141-2 L Line
Pin 16 - Battery Power
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Old 01-13-2011, 08:27 PM   #11
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This is interesting. I've been interested in watching the traffic on the can bus for a while. I thought of getting a converter from CAN to something like USB and then writing some software to read the signals from USB.
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Old 01-13-2011, 08:37 PM   #12
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I need the CAN bus because i have a CAN datalogger which will send speed signal to my headlight leveling system

My ODB II connector only has 4 wires though (2 of which are GND if im not mistaken) :/
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Old 01-13-2011, 08:45 PM   #13
El Zilcho
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Originally Posted by Pir4t View Post
I need the CAN bus because i have a CAN datalogger
How does it work? Does it have local storage that you can view afterwards, or can it feed live data to a computer?

Did you buy it somewhere, or did you build it yourself?
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Old 01-13-2011, 09:22 PM   #14
thefrog1394
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Its the K-bus that is not connected on all cars. On the cars with the round diag plug under the hood the K bus is not connected to the OBD port.

FYI not all those pins are connected on the OBD port. Newer cars connect CAN but older ones did not. It was only mandated in the US in 2008

A quick google search leads me to believe that the e46 does NOT have a CAN bus. It uses ISO 9141-2 on the diag port. If you want to decode speed information your best bet is probably to get a USB VAG-COM adaptor and use BMW INPA/EDIABAS and connect to your car's K-line. Google around INPA and you will find more information on it. Its a great tool to have anyways, you can read way more specific information from the cars computer besides the generic stuff that the OBD reader tells you. Think how the Peake tool is advertised only this is what BMW dealers and factories use. (well dealers use DIS but, whatever I digress, both talk to the computer through the K-line)
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Old 01-13-2011, 10:11 PM   #15
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Quote:
Originally Posted by El Zilcho View Post
How does it work? Does it have local storage that you can view afterwards, or can it feed live data to a computer?

Did you buy it somewhere, or did you build it yourself?
It just feeds data to the adjuster , but as it provides a 1mhz output for every km/h hooking up a logger would be pretty much cake

I bought it
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Old 01-13-2011, 10:27 PM   #16
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did anyone else read the thread title and wonder why the "i" was missing

eeeeeeeeeeeeeeeeeps
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Old 01-13-2011, 11:31 PM   #17
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Quote:
Originally Posted by Pir4t View Post
Anyone has any info on what wires(and where to find them) is the canbus ?

I've read of GREEN(HIGH)/BROWN(LOW) coming in/out of the LSZ, correcto ?
The CAN bus does not go to the LSZ. There seems to be two different wire colors for the CAN Bus. Between the ABS, steering angle sensor, instrument cluster, DME and adaptive headlight control unit it's CAN+ is Yellow/Red and CAN- is Yellow/Brown. Between the DME and the transmission control unit it's CAN+ is yellow and CAN- is white. The CAN Bus does NOT connect to the OBDII connector nor does it connect to the older DLC-20 connector under the hood.

Quote:
Originally Posted by thefrog1394 View Post
You want K-bus, thats what the BMW uses for communication. Not sure what protocol the ODB port uses but only a limited subset of information that is required for emissions purposes is available on that.
K-Bus doesn't have any engine information. You might be thinking K-Line (ISO 9141-2) which is available on the OBDII port. If you want engine specific information it's safest to go through the OBDII port, K-Line. If you look at the wiring diagram it's called D_TXD2.

Quote:
Originally Posted by El Zilcho View Post
Why not? Isn't it supposed to be?

From http://www.obdii.com/connector.html :

Pin 2 - J1850 Bus+
Pin 4 - Chassis Ground
Pin 5 - Signal Ground
Pin 6 - CAN High (J-2284)
Pin 7 - ISO 9141-2 K Line
Pin 10 - J1850 Bus
Pin 14 - CAN Low (J-2284)
Pin 15 - ISO 9141-2 L Line
Pin 16 - Battery Power
BMW E46 does not use J-2284 and CAN bus is not available on the OBDII port. The E46 uses ISO 9141-2. Look at the connector, pins 6 and 14 (CAN J-2284) are empty as well as pin 2 & 10 (J1850) and pin 15 (L-Line is optional in ISO 9141-2)

Quote:
Originally Posted by Pir4t View Post
I need the CAN bus because i have a CAN datalogger which will send speed signal to my headlight leveling system

My ODB II connector only has 4 wires though (2 of which are GND if im not mistaken) :/
Be careful messing around with the CAN bus. If you disrupt traffic on the bus you may have issues with the ABS, transmission, steering angle sensor and engine which need to be in constant communication or stuff won't work right. It's best to use the K-Line (ISO 9141-2) signals at the OBDII connector. The instrument cluster acts as a gateway to the CAN bus. It will take your requests for information and if properly formatted will send it along on the appropriate bus. If your program goes crazy and transmits garbage the cluster will ignore it and not forward it to the CAN bus.

Last edited by scottjoh; 01-13-2011 at 11:49 PM.
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Old 01-18-2011, 06:11 PM   #18
SweTurbo
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Hacked(spliced) my way into the CAN today and everything worked out perfect.

I located connector x6004 on the DME (the 2nd one on the left, has a "4" marking on the dme when plug is removed)
And then i located pins 36 and 37, coming out of these are a pair of twisted yellow wires with red and brown stripes(just like scottjoh said)

Plugged in there and my can reader lit up like it should.

Thank you scottjoh and thank you spaghetticoder
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Old 01-18-2011, 08:12 PM   #19
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Lets see the result...
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Old 01-19-2011, 01:54 AM   #20
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so your reading data from the can bus, or the kbus?
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