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-   -   F800GS CANBUS Stebel Quandary (http://www.advrider.com/forums/showthread.php?t=388453)

Dieselboy 09-24-2008 11:33 AM

F800GS CANBUS Stebel Quandary
 
Need a perspective:

I put a Stebel Compact Airhorn on my F800GS last night.

Horn worked...once...then caused the CANBUS to shut down the aux plug circuit.

Why?

CANBUS reset and the horn worked again...once.

An overly simplified diagram:

http://i194.photobucket.com/albums/z...belcircuit.jpg




A word picture of the circuit:
1- BMW accessory plug above the battery connects to 2-Relay connects to 3a- battery and 3b- AP1 Fuse Panel connects to 4-Horn Relay connects to 5a- OEM horn and 5b- Stebel Compact

Why would the horn shut down the AP1. Obviously the horn is overpowering the CANBUS, but why. It is isolated from it by two relays. I don't understand. I've used this set up on my R1200GSA with no issues.

AP1 is also running the Zumo450 and Starcom1 Advance. They worked fine for a week prior to my adding the horn. They still work fine since I've disabled the horn circuit pending further experimentation.

Help is requested.

GB 09-24-2008 11:45 AM

You need to obtain the wiring diagram for the relay for this horn used on the 12GS. I've had mine on there for several years and it works perfectly well without being shut down by the Canbus.

The wiring however, is not how you'd normally wire a horn using a relay. I don't have the schematic handy, so I can't tell you how to wire it so it works, but there is a way of doing it. I do recall there are 2 leads to the battery, 1 to the bike's +ve horn harness.. :gerg

Dieselboy 09-24-2008 12:00 PM

Quote:

Originally Posted by Gadget Boy
You need to obtain the wiring diagram for the relay for this horn used on the 12GS. I've had mine on there for several years and it works perfectly well without being shut down by the Canbus.

The wiring however, is not how you'd normally wire a horn using a relay. I don't have the schematic handy, so I can't tell you how to wire it so it works, but there is a way of doing it. I do recall there are 2 leads to the battery, 1 to the bike's +ve horn harness.. :gerg


Gadget Boy, there are actually multiple wires not depicted in the diagram. I pull the horn "signal" from the oem horn to the relay. When I push the horn button on the handlebar, that signal tells the horn relay to send power from the AP1 to the Stebel and then the stebel fires. That actually worked. But in the process of drawing power from the AP1, the BMW Aux Plug that feeds the 2nd relay (the one that tells the battery to send power to the AP1) shuts down.

Now why would drawing power from the battery--through the AP1--to the stebel, cause the CANBUS to shut down. The horn should not put any additional load on the CANBUS system at all.

The stebel intersects the CANBUS in two places: at the OEM horn and at the Aux Plug. In both cases, the connection is to a relay and that is wired to post 85 on the relay which should be milliamps of current. The only thing that current is for is to tell the switch to close and send power from the source to the device.

Source= battery Device= AP1
Source=AP1 Device= Stebel

I need ideas on how to isolate the problem. My next step is to wire the horn to the battery. That will remove one of the relays and one of the CANBUS connections. That won't however tell me why it is doing this in the first place.

rapidoxidationman 09-24-2008 05:05 PM

I don't know much about the BMW system, but I do know that when you fire a relay the induction pulse can be large and maybe the system doesn't like it. Might help to put a filter across the relay coil to dissipate the spike..

Dieselboy 09-24-2008 06:50 PM

Quote:

Originally Posted by rapidoxidationman
I don't know much about the BMW system, but I do know that when you fire a relay the induction pulse can be large and maybe the system doesn't like it. Might help to put a filter across the relay coil to dissipate the spike..

Filter, eh? From my electronic meanderings here, I seem to recall that configuration mentioned at some point. I'll do a search.

If anyone happens to have a make, model, source, I'll take that.

If the pulse is the culprit, I'm curious as to why this bike and not the R1200GSA? I suppose it's magic.

Thanks

rapidoxidationman 09-24-2008 09:30 PM

I've got a voltmeter on the Strom that's just a series of LED lights. 3 yellows at the bottom of the scale (discharging), 4 greens in the middle (just right) and 3 reds up top (too much voltage). Every time I hit the horn or turn the PIAA's off I can see the meter light up all the way for about a half second...

The horn (a Stebel) and the piaa's are both on their own relays.. Nothing has gone pop yet, but it is a concern. Maybe your 1200's electrical system is more robust and better able to handle the pulse?


IIRC from my electronics schooling, you need an RC filter (a resistor and capacitor in series with each other) put across the coil (electromagnet, inductor, kinda the same thing in this case) to absorb and safely dissipate the pulse generated when the electromagnetic field collapses in the coil when you remove power from the relay (let go of the horn button). Too big a capacitor and resistor and it'll take too long for the horn to activate, too little and it'll be ineffective. Kinda like a shock absorber for the electrical system. I'll bet somebody makes one commercially but if not I'll only ask for 20% royalty:deal

Keep us posted!

RobTheRigger 09-24-2008 10:13 PM

Do you still have the OEM horn connected? I am NOT electrically gifted, just trying to add a different perspective. I'd love to know, because I'll be puting a Stebel on my 650.

-Rob

Dieselboy 09-25-2008 02:09 AM

Quote:

Originally Posted by rapidoxidationman
...Maybe your 1200's electrical system is more robust and better able to handle the pulse?

IIRC from my electronics schooling, you need an RC filter (a resistor and capacitor in series with each other) ... I'll bet somebody makes one commercially but if not I'll only ask for 20% royalty:deal

Keep us posted!


You are probably correct. Unfortunately, this recipe is like beer, once it's on the street, it's public domain. No deal....thanks for the help. Based on symptoms this is a logical solution. More research to follow....

Dieselboy 09-25-2008 02:10 AM

Quote:

Originally Posted by Twin650GS
Do you still have the OEM horn connected? I am NOT electrically gifted, just trying to add a different perspective. I'd love to know, because I'll be puting a Stebel on my 650.

-Rob


Rob, yes the OEM horn is still in line. I did not want to run into the CANBUS diagnostic issue by changing the load on the system and having a constant fault code.

JRWooden 09-25-2008 05:38 AM

This is a thing called a "solid state relay" or "SSR" that switches power using solid state electronics (usually a triac or transistorized circuit). It has no relay coil and thus would not create any (or not as much) noise or spikes on the CANbus circuit.

Disclaimer: I'm no electrical engineer, but if you could find one that is the right size and type for this application I would think the CANbus would love you --
YMMV

Jim

JamesG 09-25-2008 05:46 AM

I think with both horns still "in the loop" you are shorting the relay and causing it to trip the error. You need to lose one or the other. Or how about wiring them in series? You might get away with that..

Crilly 09-25-2008 06:28 AM

:norton The 1200 has a 800 or so watt charging system. The 800/650 has a 400 watt charging system. Under low voltage the system sheds power. First it dumps the accessories power. I believe the horn relay is part of the accessories. I am thinking, but not sure.

Dieselboy 09-25-2008 07:09 AM

Quote:

Originally Posted by Crilly
:norton The 1200 has a 800 or so watt charging system. The 800/650 has a 400 watt charging system. Under low voltage the system sheds power. First it dumps the accessories power. I believe the horn relay is part of the accessories. I am thinking, but not sure.

Crilly, now that is intriguing. I was testing it at idle. 400 v 720 watts is a significant difference. I think I'll test that theory before anything else.

Fortunately the relay I used for the horn has a fuse slot built in to it and I pulled that to disable the circuit. Bonus-- I can reinsert it without dismantling the bike.

Dieselboy 09-25-2008 07:10 AM

Quote:

Originally Posted by JRWooden
This is a thing called a "solid state relay" or "SSR" Jim

Jim, thanks.

Dieselboy 09-25-2008 07:11 AM

Quote:

Originally Posted by JamesG
I think with both horns still "in the loop" you are shorting the relay and causing it to trip the error. You need to lose one or the other. Or how about wiring them in series? You might get away with that..


JamesG, no dice. I'm not getting an error. The OEM horn works even with the Stebel.


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