CANBUS

[pitrat101]

Hey guys, I am new to this CANBUS system on the BMW and still trying to get my head round it, so far figure everything is controlled from main ECU through modules that know what happening when lights and stuff switched on! so just wondered if anyone could shed any light on what leeway with load if any you can get away with without popping warning lights on? or shutting down a system? Please correct me if I am way off!

Thanks

Steve

 

[Stevie4scoops]

I've connected relays to things powered by CAN Bus without triggering any warnings. I don't think it would take much more than the relay solenoid load to cause a problem though.

 

[Engineer]

Hey guys, I am new to this CANBUS system on the BMW and still trying to get my head round it, so far figure everything is controlled from main ECU through modules that know what happening when lights and stuff switched on! so just wondered if anyone could shed any light on what leeway with load if any you can get away with without popping warning lights on? or shutting down a system? Please correct me if I am way off!

Thanks

Steve

You would need to know the load limits for each controlled circuit, not sure if BMW publish this - so best to add nothing more than a small relay coil drive load onto the existing circuits and put the heavy current direct from the battery through the relay contacts via a suitably rated fuse.

 

[Pukmeister]

CAN is just a way of controlling items, it doesn't do power itself (although it can limit power draw based on the software settings, for example the auxiliary socket is limited/protected by the can bus control setting at 5 amps maximum).

If you wish to add items to your bike, you can do it via a fused supply direct from the battery or via a relay depending on the current drawn. Typically you can add extra power sockets for heated vests etc, a switched power feed for a satnav, or fog/spot lights etc.

I have a 'Fuzeblock' accessory panel under the seat on my GSA triggered from the sidelight bulb feed (ignition) which can provide both switched and unswitched power for accessories. Other similar devices are available.

There are some "useful links" in the sticky section of the 1200 forum that can explain how to do switched power easily, plus much more.

 

[Wapping]

Canbus is not magic; electricity is electricity no matter which way you chop it.

The draw on the individual circuits are pre-set by BMW and, with the exception of the under seat auxiliary socket (5 amps) are not generally known. There are threads on some American forums where bods have patiently unpicked the codes, to add things like oil temperature and pressure gauges - both of which are used in the engine's management system's calculations - but, for understandable reasons, it's not easy.

A simple bog standard relay (or even simpler, a fused lead) will sort out most things, more than comfortably. Besides the ever popular Fuseblock, there are now digital versions *, with the relays built in. Some you can pre-programme, too. Quite tidy, really.


* PDM for example