How to: CAN bus and 3rd party alarm wiring

[Mouth]

Hi,
First my introduction and then my question [^]

Got my '07 grey ST on Fri evening, and after 450km I love it. I hail from AUS, and have been riding for about 12 years. Yam FZ6, Honda 1000F, and Honda VFR800 have been my bikes for last 5 years. I know it's very early, but I already feel/know the F8 ST is the best of them [8D]

Been lurking/reading the forum for a little while and learnt lots from reading many threads from top to toe. Haven't had anything to contribute or ask until now. I'm also co-owner and admin of Australia's most popular motorcycling community website.

Now my question...

I brought a basic alarm to go on the ST. Nothing fancy, just two wires to connect and it has a movement sensor so it can sound-off in case any 'chumps' want to sit on it or roll it away. Won't stop any pro (will any alarm?), but at least it will stop any opportunists and anyone who thinks that can just have a fiddle.

The alarm requires a connection to battery positive terminal (easy!) and the 2nd wire to an ignition wire that has 12V when the ignition is on and no volts when the ignition is off. It then just automatically arms and disarms with the ignition key and requires no fob etc. The circuit used also needs to have less than 4ohms DC resistance when the ignition is off.

So, through reading through these forums, I decided that the accessory/gps connector located near the battery underneath the rhs fairing about knee height/position would be a good one to use for the alarm's ignition lead requirement. It has 12V when the ignition is on, and no voltage after ~60 secs from turning off the ignition. The connector also has 0.7ohms DC resistance with the ignition off. Sounds perfect, except the alarm isn't arming, and thus sounding when the bike is moved :(

I immediately thought the CAN bus was to blame, but with some more thinking I'm not so sure. My thinking now is that because this accessory/gps connector that I have 'spliced' into does not have any device attached/connected to it, then there is no 'join' between the live/12V wire and the earth wire giving the DC resistance. And thus the alarm won't be arming because it's not getting the < 4ohms DC resistance it requires when I turn off the ignition? (It's getting no resistance at all?) Anyone with more electrical knowledge than me (not hard!) like to comment or confirm/deny?

I checked the 2 wires going into the park light within the headlight assembly, and they provide the same results - 1 wire providing 12V with ignition on, and the other providing DC resistance of 0.7ohms with ignition off. The only difference is that this has a globe/lamp/connector that is 'joining' the live and earth together?

Am I thinking in the right/accurate direction here, or just showing my electrical ignorance? Maybe the above doesn't apply at all and it is the CAN bus causing my issue?

Has anyone else attached a non BMW/OEM alarm? If so, what circuits/wire did you use to connect into, if you required a 12V active connection with ignition ON?

If I am correct about the accessory/gps connector requiring a device attached/connected to it to complete the circuit and pass through the required DC resistance to the alarm, then what is my best solution? Should I ignore/detahc from the accessory/gps connector and use something else, such as the park light connection? Since the park light connector and wiring is a little 'exposed' then perhaps I'd be better using another connector/wireing that is more hidden/enclosed? If so, what connector/wiring would people suggest?

http://www.ignitoralarms.com.au/Installation.html is the alarm if your interested. It also has installation details and installation manual as PDF if that helps anyone in answering my question.

Sorry for my long winded post, and thanks for reading if you've come this far :) Thanks.

[Pat H]

Hi and welcome.

re the alarm I think your right on the GPS connector. It won't have any load on it when the ignition is off so the alarm enable sensing wire isn't be dragged to ground (via the 4 ohm) so not sensed.

The park light should work and if you track the wiring back you may find a less exposed place. Or what about the rear tail light? That comes on with the ignition as well.
Or power to the rear brake light switch (although probably won't have a 4 ohm load when off)

Good luck and post back results.
I have the BMW alarm because it integrates nicely and well it was only money at the end of the day.

[SMB]

Hi and welcome,
I have added accessories to my ST. However I am fearful of the CanBus system, and did not want to load the original wiring circuits. I am not sure that the brown wire (the earth wire)is a direct connection to the negative of the battery. I used a small 12V relay (when I say small it takes about 17mA 0.017A Coils resistance of 720 ohms). I wired this in parallel to the tail light. I also added a diode to take care on any electrical spikes well the relay switches off; though not really necessary as it will discharge though the tail light filament. When ever the ignition is on the relay closes and I can use the relay contact to operate my accessories. This isolates the accessories from the CanBus system. You could do the same.

Attached Image:
http://F800Riders.org/forum_old/UPLOADED/smb/2007121113525_Picture5.jpg
23.3*KB

However I am sure that there will be many other ways to achieve what you require.
SMB

[Butzull]

Hi Mouth,

Fancy seeing you here! But Grey??? Tsk...tsk! ;)

I'm pretty clueless when it comes to electrics so may not have understood the issue correctly, but if the grounding to close the circuit is the issue, did you ground it directly to the negative terminal of the battery? I was told sometime that it is the most reliable/best ground on the bike, rather than also splicing into a grounded wire.

I spliced into the accessory socket wire for the positive of my Autocomm and the negative directly to the battery terminal and it works like a charm, cutting out the requisite timing after switching the engine off.

Hope you get it all sorted, and we've gotta have that coffee one of these days and go for an F800 outing. ;)

Good luck and happy riding!

Gav.

[Mouth]

Originally posted by Butzull
we've gotta have that coffee one of these days and go for an F800 outing. ;)


Absolutely :) I can even show you that the grey one's go faster :P ;)

[Mouth]

Originally posted by Pat H
re the alarm I think your right on the GPS connector. It won't have any load on it when the ignition is off so the alarm enable sensing wire isn't be dragged to ground (via the 4 ohm) so not sensed.

Yup, this is the problem. I emailed the alarm seller, and he confirmed that it will because there is nothing plugged into the connector so the DC resistance with the ignition off is not be transferred/joined back to the live wire that I spliced into.

I can either move the alarm connection to one of the park light or tail light wires, or alternatively get a connection plug for the GPS connector and complete the circuit so the DC resistance gets passed. I must admit I think I'd prefer the latter since I've already wired it in and spliced it etc. and like the wire placement instead of having to go all the way back to under teh seat for the tail light (park light is too exposed and goes into a bigger wiring loom).

Anyone know if the GPS connector and wires are sold seperately? If so, perhaps a part number? :D Or maybe I could just get a small piece of wire and cross/join the live and earth wires?

[Butzull]

Originally posted by Mouth

Originally posted by Butzull
we've gotta have that coffee one of these days and go for an F800 outing. ;)


Absolutely :) I can even show you that the grey one's go faster :P ;)

I'm sure that's not fair. I don't even pretend to be a great rider...and I'm a bit of a blouse to boot! ;)

Re: Short-circuiting, we've already established I know nothing, but wouldn't that slowly drain the battery?

Butz. [booze]

[Mouth]

Originally posted by Butzull
I'm sure that's not fair. I don't even pretend to be a great rider...and I'm a bit of a blouse to boot! ;)
Aren't we all, otherwise we wouldn't have BMW's :) I was, of course, speaking metaphorical.

Originally posted by Butzull
Re: Short-circuiting, we've already established I know nothing, but wouldn't that slowly drain the battery?
Yeah, I think your right. Going to bite the bullet and just re-wire it into the tail light wire/circuit, when I get an hour or 2.

[Mouth]

Originally posted by SMB
I am fearful of the CanBus system, and did not want to load the original wiring circuits. I am not sure that the brown wire (the earth wire)is a direct connection to the negative of the battery. I used a small 12V relay (when I say small it takes about 17mA 0.017A Coils resistance of 720 ohms). I wired this in parallel to the tail light. I also added a diode to take care on any electrical spikes well the relay switches off; though not really necessary as it will discharge though the tail light filament. When ever the ignition is on the relay closes and I can use the relay contact to operate my accessories. This isolates the accessories from the CanBus system. You could do the same.

Thanks for the advice and diagram. As my alarm already has it's own power source direct from the battery, I think I'm fairly safe in hooking it to a CAN bus wire, since all it's looking for is a DC resistance when the ignition is off and not drawing any current from the system. If I was going to draw current, I think I'd definantly do what you have done and described.

[Mouth]

Just to close off this topic, in case anyone is reading/researching in the future. I completed wiring the alarm the other day.

The alarm connected directly to the battery, and also to a 'suitable' ignition wire. The definition of a suitable ignition wire for the alarm was one where 12V power existed when the ignition was on, and the same wire provided no more than 4ohms resistance to earth when the ignition was off. It recommended the live tail light wire, live parking light wire, or live instrument cluster wire as examples.

I initially thought I'd use the BMW GPS connector live wire that exists just near the battery, but since I have no GPS or other device on this connectore/wire, there was no ohms resistance provided when the ignition was off, so this didn't work.

Following SMB's suggestion/diagram above, I decided to use the live 12V tail light wire as the ignition wire. I confirmed that it had 12V when the ignition was on (with or without engine running, and also whilst cranking/starting the engine which was important for the alarm) and also that it had 3.1 ohms earth resistance when the ignition was off.

For those wanting to know, the connector for the tail light (and brake light, and both sides rear indicators) is under the seat almost exactly center and almost exactly underneath the rider's backside. Just follow the wrapped wires that runs to the rear lights along the left side of the bike. It's easy to identify.

The tail lights 12V live wire in the above connector is the one in the 3rd (of 6) connection 'pins'. There are only 5 wires to/from this connector. Each 'pin' on the connector is marked as either 1,2,3,4,5, or 6. Number 3 is the tail light wire. (Earth, brake, left indicator, and right indicator are the other wires on the connector).

After wiring in the alarm it works fine, and there is no problems with canbus. And no problems with the computer thinking that there was a light/globe problem either. I also checked the computers blown/faulty globe reporting still worked too, by both removing the globe in the tail light and also pulling apart the connector under the seat. In both cases it still reported a globe/light problem :)

So it's acceptable to use the tail light as an ignition wire without causing problems with canbus and the computers globe/light detection.

If any accessories that you are wishing to wire to your bike don't need an ohms resistance (as would be the case in the majority of cases I would think) then I would suggest you use the BMW GPS connector 12V wire instead though.

[de100kb]

Thanks for the full report Mouth [clap] I moved this thread to the Hall of wisdom (so it's more easily found) and changed the name a bit.

Thanks for sharing :)