2007RT, Did the Canbus eliminate fuses?

AntonLargiader said:

This is a different misunderstanding, but OK.

If you think there is a missing fuse between the ZFE and the headlight, there isn't. The ZFE acts as a circuit breaker for that part of the circuit.

If you think there is a missing fuse between the battery and the ZFE, then you misunderstand the whole concept of overload protection. Protection is not to protect the device; if the device is drawing too much current then it is already bad. Fuses and the like protect the wiring that feeds the defective device which is trying to draw too much current.

So when you ask, "What protects the ZFE?" what is it that you think the ZFE needs to be protected from?

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The purpose of a fuse or circuit breaker is to limit the amount of current passing through a circuit. LOOK AT THE CIRCUIT DIAGRAM and you will see there is no fuse or circuit breakers BUT the circuit goes THROUGH the ZFE. As you said the ZFE operates as the circuit breaker. That built in circuit breaker has design limits. Exceeding those limits causes bad things to happen. A microprocessor is pretty delicate and lots of current tends to be hard on them. The circuit breaker and for that matter a fuse depends on tripping rapidly. If it doesn't the entire circuit that is involved heats up. Commonly called frying. If you think this is BS, do a search on "motorcycle ECU fried", it happens to cars too. My position is that yes, Canbus "could" eliminate fuses, but do you really want it to? I'm sure you won't understand that.
http://www.r1200gs.info/R1200GS-WD2.pdf - Wiring Diagram
http://www.bmwra.org/otl/canbus/ - how canbus is implemented on R1200gs
CANBus is a protocol, period. What does that means? You can do the homework and find out. Does it make your bike faster? No! Does it make it more fuel efficient? No! Does it make it more reliable? Yes and no.

BernieEcht said:

Let's go back to 6 volt systems with candlelight head lights.

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All 35 watts worth...



And no fuses to protect against "major power", either.

chewbacca,

i'm not sure you're actually a real person but I'm giving you the benefit of the doubt. You've proven my initial comment several times over now, you're evading questions, and your posts are't even consistent with themselves. I'm sort of glad you found my article but it certainly wasn't the source of your bizarre bit of fabrication regarding ZFE and GS911.

The forums are here for the benefit of club members. You have a question, fine, you have some knowledge to share, fine. I have no idea who could possibly benefit from your posts, yourself included.

I hope your next foray into a technical thread goes better, but I'm out of this one.

chewbacca,

There are many ways to accomplish the same goal. BMW picked CanBus to provide communications between intelligent modules on the bike, and uses electronic circuit breakers to protect the bikes wiring. Other bikes use different systems, as do cars. Personally I think BMW made an intelligent choice, which may not be popular with some riders used to fuses and branch-circuit wiring harnesses. It's fine to have that opinion, but in this case BMW isn't going to revert back to it, and many people find the improved reliability a real plus in the real world. As was also pointed out - the GS-911 is a diagnostics device, not at this point a programming device, and there is no "limp-home" mode on the bikes that it would be capable of enabling. Also - CanBus does NOT eliminate fuses. It only provides communications. A solid-state circuit breaker (as used in the ZFE) monitors the current flowing to a circuit and if it exceeds a predetermined value, it shuts that circuit off. Just like a fuse - but much faster, and automatically resettable when the fault is fixed. The ZFE does not control the engine - that is a different module entirely (and it could be referred to as a ECU, except BMW likes to use different names, and it's the BMSK or BMSK-P.)

As I mentioned before - the failure rate of ZFE modules seems to be about zero. If you have any info to the contrary, I'm all ears - but minus that, it's a non-issue, and at this point, I'm considering closing the thread. It isn't terribly productive to have arguments about what BMW has already done, and is not going to un-do in a technical forum.

lkraus said:

I've never heard of a ZFE being damaged or needing replacement. Apparently it can take care of itself...

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My '07 now-lemoned F800S probably had a faulty ZFE but after replacing the Can-Bus, BMW bought the bike back, not taking the ZFE as a chance.

Now I have a much better bike.