CANbus Resistance Values

[WarthogARJ]

Hi,
Is GREAT to now have a way to change from MILES to KILOMETERS.
Thanks.

What I'd like is a way to reset the common CANbus lighting resistance values for the indicator lights, taillight, and the main headlight.
It's a very common upgrade to add in an aftermarket LED but if you don't have some sort of power resistor you get a CANbus fault.
I have an HP2 Enduro, but I'm sure all you lesser mortals with those other BMW bikes might want this too...:-}

So you have to add in a power resistor.
Which fools the CANbus.
But you waste power.

I'm sure that the CANbus system checks a registry for the resistance value.
Be nice to adjust that to the value of the LED you added.

Of course if Stephen cannot figure out how to do that, well we shouldn't stress him about it.
Dang.
He might get upset and kick his dog.
Yell at the wife.
Heavens.

Then we'd be responsible for his dog biting him and for his subsequent relocation to the dog house due to his wife not being happy with him.
Imagine having to share the dog house with a dog you just kicked?
Poor dog.
No.
So just forget about it.
I'm SURE it's just too hard to do.
Sigh......:-}

Alan

[Haakon]

The Hexcode team can not make "magics"- even tho it often seems they do :-)))
They are restricted by how BMW programmed the ECU.
If the BMW GT1 (Their $$$$$ computer) can not change the resistance values then the GS911 also can not.
I know it "can" be done but not unless you rewrite the ECU software... almost impossible to do for a "small" firm.
(as a example: 11 years ago one of Germanys main chiptuning firms were asked to just find the ignition part of the GS F650 ECU (so "we" could modify it) The time and price for a "simple" task like that was HUGE!!
----------
Even with full access to the code its a enormous task to modify it- AND make sure the rest is not altered.
If BMW ever offer other types of "bulbs" there will be modifications done to the ECU code...  and then Hex will be able to use that in a new Beta :-)))
Haakon

PS: I am NOT working at Hexcode.
The easiest way is to cheat the CANbus with  external electronics that give the CANbus the values it expect.       

[WarthogARJ]

Yeah I know.
The dogs in Stellenbosch have BIG teeth.
And Stephen's wife has a great left hook.

Sigh.

Seriously, the info MUST be stored somewhere.
In an array.

[Haakon]

Seriously, the info MUST be stored somewhere.
In an array.

Yes, I fully agree. The problem is to find it- and how to modify it.
I do NOT know anything re: the BMW CANbus system but I bet its not "open source" or "easy" to crack and read/ modify.
Unless BMW come up with a updated ECU/CANbus software that have that as a option its almost impossible to do.
Not impossible, but just way too time consuming AND expensive to even try.
-----------------
Some of the firms that sell LED lights tell its CANbus "usable"- is that just cheap resistor solutions??
   
 

[WarthogARJ]

So, Stephen, what say?
You afraid of your dog or your wife?

Seriously, is it not possible to find the resistance look-up table in the firmware?

[kobus]

Stephan is currently in the US busy with the BMWOA rally.

While I understand it's spoken in jest, I would suggest we rather leave wives (and dogs  ) out of discussions on this forum.

As to your original question the answer is basically that what you want has nothing to do with "CANbus Resistance Values" but rather with re-coding the ZFE to know what hardware is fitted. Figuring out how the coding work is a difficult and time consuming process and must be done correctly or risk breaking the ZFE controller.

We'll add more coding functionality as and when we are confident that it is done correctly.

I suggest you read up on what a CAN bus is.

[WarthogARJ]

I've owned a GS-911 since 2009: it's a useful tool, but a bit limited in some aspects.
I do all my own maintenance.
My last job was stripping down my HP2 to the bare engine.

And I don't have a wife or a dog, but I do have a sense of humor.

And thank you, I understand what CANbus is.
I was using the term loosely, and if one wants to be more technically correct, then I am saying that it would be very useful to be able to modify the values that the ZFE module looks up when it gets the resistance values back VIA the CANbus system.

Incidentally, if you buy aftermarket items, the manufacturer uses the term "CANbus" friendly: meaning they don't get an error message issued.
So that's why I use the term myself: it's the terminology people understand.

What I don't know specifically, and if you don't know either, join the club, is how the ZFE module decides that there is a lighting error: by using an LED instead of an OEM incandescent bulb.
When I last spoke to Stephen about modifying the system via the GS-911, he said that he was concerned that allowing that would allow too great a chance for a SNAFU and potentially scramble the modules if people messed it up.

That was specifically about changing from km to miles.
However I now see that you CAN do that.
Great: I've had to change mine twice: from miles to km and then back to miles.
And each time via the dealer.

I THINK the system measures the lighting resistance and if it is too low or too high it thinks it's a short, or open-circuit.
And issues an error message (via CANbus) to the other modules.
In my case to the instrument cluster module.

But HOW does it measure the resistance?
Is this firmware or hardware?
Like does it use the equivalent of a galvometer to measure the current to the specific item?
And is there ONE internal device for this?
Or perhaps are there a number of small resistors hardwired in the ZFE module so that when current goes to the specific pin (for the headlight it is pin 56 of the ZFE) the voltage drop is measured.
If so, this is a hardware thing and hard to change.

Anyways, I'll wait until Stephen is back and will email him directly about it.
Some Chinese manufacturers seem to have figured out how to do this, so I'm hoping Stephen "wil 'n Boer maak 'n plan".

[marki_gsa]

The ZFE unit most likely measures current drawn rather than resistance and your probably right in that it will use a lookup or reference a coded figure and decide from there whether it's all good or something is broken. It will be changeable but whether it can be done outside BMW is another matter. These units aren't particular to a specific bike but the software in them is if that makes sense. The PDM 60 is a good example of a basic and limited version of the ZFE unit. In theory the lower current limit could be removed (you would never get lampf) or could be lowered (widening the acceptable range) but I doubt this can even be done with dealer equipment. It's most likely flashed at manufacturing and locked since as far as BMW there is no real reason for it to ever change. The new LC bikes will most likely simply have an option setting 1-halogen 2-LED type thing so the values of them still won't be changeable.

[bikecrazy5]

hi guys
there is s much that can be argued about on this subject. I know there are certain things that can be changed at the dealers i.e. a change from normal globe indicators to led indicators and gets done as a retro fit  on there diagnostics system all this is set up by the bmw boffins in Germany. the dealers cant alter any values and resistance values as far as they know its locked...

[WarthogARJ]

That's interesting.
Is the first I heard that they can do it.
I did ask the dealer I go to about LED's, but not specifically that question.

I will ask.
If it's right, then problem solved.
But so far I have seen many people posting on various forums with LED Canbus errors, and nobody has ever said "hey my dealer solved my problem".
After all, BMW doesn't sell these items, so why would they solve the issue?
And in many places the HiD's are not approved.
They are not in the UK.
Nor as far as I know in Germany or the USA.
So if your dealer DOES do something that lets you run HiD's then he's just done something that's not allowed by that country's traffic laws....

Anyways, if so, I will post this solution widely: it's not going to be very expensive.
And save a lot of headaches.

[bikecrazy5]

don't get me wrong the led indicators are original bmw indicators from the newer models just retrofitted on to the older bikes

[WarthogARJ]

Aha.
OK, I understand now.
But the dealer did not have to change anything to do this.
The newer LED's come complete with resistors to make the CANbus system think you still have the OEM bulbs.
You just plug in the new ones.
I did this myself on my bike: I installed them myself.
No errors either.
You have to order the resistors as an extra though, and the parts guy for my dealer did not know that the extra "harness" was in fact a resistor to do this.

My only issue was I needed two sets of rear LED's since the front set don't fit the HP2.
But they are great LED's I agree.

[WarthogARJ]

I was looking at some other forums.
I think the closest I've seen to a solution is to power the HiD bulb directly from the BMW wiring and not use a relay.
And as long as the ballast has the same resistance as a BMW OEM H4 bulb then no Lampf faults.

But it would need to be happy for BOTH the High and Low beams.

I'll try that though: can use a couple of diodes to supply power to the ballast from either low or high beam parts of the OEM socket, but not allow them to short each other.
And then switch the HiD H4 from the High beam voltage.

Only other option is live with the Lampf faults, or else use a power resistor.

Until the Mighty HexCode GS-911 Team figures out the code!!

[Haakon]

Re headlight and HID`s
Does anyone know the (resistance) values the "CAN-bus" accept?
There must be some leeway + and - ?
I do not think Hi or Lo matters
On my "table", add bad connections and so on...
My guess is the resistance can be between 2.0 to 5.5 ohms??
 
50W
12V
= 2.88 ohm
-----------
50w
14v
= 3,92 ohm
----------
-----------
45w
12v
= 3,2ohm
------
45w
14v
= 4,35ohm
-----------
Most HID ballasts draw 35Watts when the bulb is fully "on"- more during the first seconds, while its "charging".
35W
13v
= 4.8 ohm`s
------------------
I am way too tired to think so I cheated- using one of the many online "calculators"
http://www.rapidtables.com/calc/electric/watt-volt-amp-calculator.htm
For the paranoid, use the link on your own risk :-))))
 

[WarthogARJ]

Haakon,
That was a good idea.
Yes, I think you're right about the resistance.

I'm going to try running the HiD ballast direct from the Low and High Beam supply of the BMW circuit.
Use a couple of diodes, and run leads to the ballast input.

And use the High/Low voltage to power the H4 High/Low beam to change filaments: as my current system does.

i think my HP2 system is a bit unusual: BMW brought out CANbus is 2004 and that's when the Hexheads started.
But they've all got OEM H7 bulbs (single filament), and not H4.
The H4 is a dual filament Hi/Low Beam.

Alan