Dispelling more CAN-BUS Myths

[Ken H.]

'Don't touch the electrical system in the new CAN-BUS bikes, it'll melt down into a molten mass right before your eyes!' 'Or at the very least set faults, void the warranty', blah, blah, blah. To which I say, "Baloney!"

 

Last night I added the Kisan HD-100M brake light modulator to my Nippy Norman's LED tail light array. Works great, no faults, no meltdown. Going to try their headlight modulator next.

 

Point is, I don't think we have to be as shy about doing things to these new systems as some would have us believe.

 

Cheers!

[steveknapp]

It's hard to give advice on the internet.

 

It requries some common sense.

 

Which may or may not be common.

[John Moylan]

.....like the article in a recent copy of the BMW Journal - the Club's monthly magazine over here and the UK............

 

It bemoaned that it wouldn't be possible to use secondhand units as mundane as a rear light, in the event you damaged yours, and bought a used unit from a breaker's yard, because it had an 'address' that wouldn't work with your ECU..and you'd be forced to buy a new one, and get it 'programmed' to match your specific bike by the main dealer.........puhleeez!

 

If anybody honestly thinks that BMW would have invested the $$$ to even bother do this......they're deluded. Sure s/hand assy's will have 'addresses'.........but they're global. All brake lights will have the same address. All headlights, etc.

 

Some parts will be unique, possibly because of alarm functions, but really, the CanBus has just left the building....here comes the Scam Bus instead !!

[steveknapp]

John, that's absurd. There are only three nodes on the CAN bus. The ECU, the brake module, and the "ZFE".

 

Someone at some point heard CAN, and looked it up, and saw what it COULD be...basically a network node per electrical device. Nevermind that this isn't common practice, nor is it cost effective...

 

OTOH, it is possible that to make the bike more theft proof the three CAN nodes might need some syncing up. But the brake light itself? Or the headlight? Or...well you get the idea.

[Emoto]

.....like the article in a recent copy of the BMW Journal - the Club's monthly magazine over here and the UK............

 

It bemoaned that it wouldn't be possible to use secondhand units as mundane as a rear light, in the event you damaged yours, and bought a used unit from a breaker's yard, because it had an 'address' that wouldn't work with your ECU..and you'd be forced to buy a new one, and get it 'programmed' to match your specific bike by the main dealer.........puhleeez!

 

If anybody honestly thinks that BMW would have invested the $$$ to even bother do this......they're deluded. Sure s/hand assy's will have 'addresses'.........but they're global. All brake lights will have the same address. All headlights, etc.

 

Some parts will be unique, possibly because of alarm functions, but really, the CanBus has just left the building....here comes the Scam Bus instead !!

 

The controller has the address, not the object getting the power. The controller allows X amount of power through. If something/anything tries to exceed that limit, the controller shuts it off. So, you can change whatever you want downstream of the controller for a particular object as long as you do not exceed the limits - whatever they might be. Example: put a different horn in place of the OEM unit. It will work fine unless it is a really loud one, which will make it draw "too much" power. It will honk for a second or three and then the controller will shut it off.

[steveknapp]

So, you can change whatever you want downstream of the controller for a particular object as long as you do not exceed the limits - whatever they might be.

 

Which brings me to my winter project...

 

What *are* the thresholds for the various bits on this bike.

[Ken H.]

There are only three nodes on the CAN bus. The ECU, the brake module, and the "ZFE".

Yeah, after all the hype about CAN-BUS, imagine my surprise when I started studying the bike's schematic and low and behold what do we have? Plain old wires running from all the 'stuff' (lights, horn, etc.) to a central control box, the ZFE.

 

Things have gotten more complicated in bikes, but fortunately we're not yet to the point where each $4 light bulb has it's own address and has to be programmed!

[James Clark]

John, that's absurd. There are only three nodes on the CAN bus. The ECU, the brake module, and the "ZFE".

 

Don't forget about the instrument cluster.

 

And the CANBus interface for the scan tool.

 

And what about a fanatical devotion to the pope?

(Oops. Wrong routine.)

[steveknapp]

Don't forget about the instrument cluster.

 

Hmm.. good point ... Ken, my wiring diagrams aren't 100%

 

And the CANBus interface for the scan tool.

 

It's a connector, but not a node on the network until the diag tool is connected. This assumes you don't just have a K-line connection to the ECU, and then have the ECU talk on the CAN bus for you.

[steve.foote]

Also, keep in mind that virtually any of the electrical lines leading to various endpoints can be tapped to switch relays hooked directly to the battery. The accessory circuit is an excellent place to switch relays.

[SiamJim]

Also, keep in mind that virtually any of the electrical lines leading to various endpoints can be tapped to switch relays hooked directly to the battery. The accessory circuit is an excellent place to switch relays.

 

Not necessarily true. In my case, I tapped the low beam wire for my motolight relay. The lights worked fine, but set an error message in the ZFE. The ZFE didn't disconnect the circuit, just gave an error message. The BIG problems came when the idiots at BMW Thailand couldn't interpret the error message and gave me massive grief.

 

As was said earlier in the thread, each consumer (electrical components) is given tolerance levels or amps/volts/resistance (not sure which one or the mix) and if there is an exception to this tolerance, an error gets reported or the circuit is broken, or both.

 

I think the accessory plug is given the most tolerance so should be used for most hard-wired accessories.

[SiamJim]

'Don't touch the electrical system in the new CAN-BUS bikes, it'll melt down into a molten mass right before your eyes!' 'Or at the very least set faults, void the warranty', blah, blah, blah. To which I say, "Baloney!"

 

Last night I added the Kisan HD-100M brake light modulator to my Nippy Norman's LED tail light array. Works great, no faults, no meltdown. Going to try their headlight modulator next.

 

Point is, I don't think we have to be as shy about doing things to these new systems as some would have us believe.

 

Cheers!

 

Ken, after you installed the lights, did you have the dealer hook it up to the computer?

 

Like I said above, my lights worked fine but the set an error and gave the dealer an excuse to make my life miserable. I would have been happy to live with the tolerance error but in my case it just confused the hell out of the dealer when I brought the bike in for two unrelated problems.

 

I guess my point is, it's not such a complex and risky proposition on the bike, it's an ignorance issue on the part of BMW - some dealers excepted of course.

[Ken H.]

Ken, after you installed the lights, did you have the dealer hook it up to the computer?

Dealer? I don't need no stink'n dealer! Especially are local one who thinks "canbus" is something you smoke out back when nobody is looking.

 

Actually when I said "no faults", I was referring to no instrument panel indicated faults. I suppose it's possible an internal one might be recorded and not displayed to the rider, but I kind of doubt it. The whole point of the thing is to tell the rider something is up with a light circuit.

[SiamJim]

Dealer? I don't need no stink'n dealer! Especially are local one who thinks "canbus" is something you smoke out back when nobody is looking.

 

Good on ya Ken.

 

Actually when I said "no faults", I was referring to no instrument panel indicated faults. I suppose it's possible an internal one might be recorded and not displayed to the rider, but I kind of doubt it. The whole point of the thing is to tell the rider something is up with a light circuit.

 

Actually, I know it's possible to have an error on the ZFE without any indication on the instrument panel. This is exactly what happened with my lights. I wouldn't worry if your bike is working properly, my point is that you may bring it to the dealer and they would see an error and it could turn into a shite storm. I'm not trying to be an alarmist, just point out a potential risk.

[steve.foote]

Also, keep in mind that virtually any of the electrical lines leading to various endpoints can be tapped to switch relays hooked directly to the battery. The accessory circuit is an excellent place to switch relays.

 

Not necessarily true. In my case, I tapped the low beam wire for my motolight relay. The lights worked fine, but set an error message in the ZFE. The ZFE didn't disconnect the circuit, just gave an error message. The BIG problems came when the idiots at BMW Thailand couldn't interpret the error message and gave me massive grief...

 

Jim, I have my motolights tapped on the low beam and the PIAA 540's tapped to the high beam (through relays, of course). I've had the computer read a couple of times since and no errors noted.

 

Considering the amount of current the stock lights draw, I can't see how the relays could make much of a difference.

[R4ND0M_AX3]

Anyone know if the Alarm is a node on the CAN bus or is it just wired direct to the ECM?

[opampca]

Anyone know if the Alarm is a node on the CAN bus or is it just wired direct to the ECM?

The alarm is a node, i mean the optional alarm. Looked at the GS diagrams and also found out that there is no access to the canbus on the diagnostic plug. Tonight i hooked my canbus evaluation board on my R1200ST. Lots of trafic there. I had to unplug the I-cluster, so maybe error messages were sent. I received more than 20,000 messages in 11 identifiers in 1 minute after ignition on. We should not ge so worry about the canbus, which is not a single wire, as advertised, but a regular hi and lo canbus at 500kbit/sec. I do not either think that adding a small relay coil on a 55watt bulb circuit would be detected by the zfe.

[SiamJim]

Jim, I have my motolights tapped on the low beam and the PIAA 540's tapped to the high beam (through relays, of course). I've had the computer read a couple of times since and no errors noted.

 

How did you tap the low beam? BMW said the error was cause a change in resistance becaue of the splice connector. I don't rely much on the info I get from BMW, but I did see the error get set when the lights were connected and no error when they were disconnected.

 

when I spoke to the guys at Motolight, they said it was crucial to solder the connection. I ended up soldering the relay power to the + connector on the rear accessory socket and now no errors are reported.

[steve.foote]

How did you tap the low beam?

 

I used a regular crimp type tap. This winter, I plan on doing a proper soldier job.

[James Clark]

. . . a proper soldier job.

 

 

I

CAN'T

HEAR

YOU!!!

[steveknapp]

I received more than 20,000 messages in 11 identifiers in 1 minute after ignition on.

 

That does not seem unreasonable. Care to post the dump?

 

We should not ge so worry about the canbus, which is not a single wire, as advertised, but a regular hi and lo canbus at 500kbit/sec.

 

I agree about not worrying, but single wire, 2-wire...what does it matter?

 

I do not either think that adding a small relay coil on a 55watt bulb circuit would be detected by the zfe.

 

Depends on the relay and the ZFE. Some draw 300-500mA. That's hardly noise to any reasonable current sensing scheme.

[Ken H.]

Today I added a Kisan pathBlazer Headlight Modulator on the high beam on our R1200GS and it functions fine with no bulb out fault displayed on the dash.

 

Also a Stebel Nautulus Compact Airhorn with relayed power, which also functions fine on the bike.

 

And wired in our heated seats.

 

I have to say, to even my own surprise somewhat, every modification or addition I have done to the bike has worked fine and not upset anything. Guess I've gotten lucky!

[steveknapp]

Ken, FWIw, some of the modifications people have performed, like adding extra brake lights, may not cause faults. But they MAY disable the "lamp failure" functionality.

 

Still not the end of the world. At least not the end of the world I live in...

[Ken H.]

But they MAY disable the "lamp failure" functionality.

 

Still not the end of the world. At least not the end of the world I live in...

Yeah I'm with you, I aways thought the whole lamp monitor thing was a bit over the top.

 

I've had a lamp monitoring system on every bike I've ever had. It's called looking at them!