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CANbus Resistance Values

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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  :-X) 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.

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