No start, bcm?
Seasoned HDF Member
Joined: Sep 2008
Posts: 14,144
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From: San Diego, CA
Been on a trickle charger all night, shows 12.8 volts at stand by (surface charge worn off, no load on battery such as key switch on). Can't get it load tested today, everything is closed. Can someone explain to me why I am not getting 12 volts from the bcm to the exciter wire when start button is pressed? Am I wrong to assume it should get 12volts? At less than 2 volts, I don't think that would be enough for the the solenoid to pull the contacts together, in turn sending the 12volts from battery to the starter motor
I believe there is a spec in the Electrical Diagnostic Manual for that output from the BCM to solenoid.... but less than 2 volts does seem a little light... I have noticed that in the canbus system, there are some trigger volatges that are like 5v or maybe even 3V.... not all are 12v....
As many have suggested, with any electrical issue, I always start with ensuring the battery and it's connections (especially that ground wire forward of the battery to the frame) are good.
If your battery/connections check good, then the code thrown and the seemingly low voltage from the BCM would suggest to me the BCM is bad. Or there is an issue with that wire between the two. If you know someone with the appropriate Electrical diagnostic manual (I don't have one for thjat year/model), maybe they could check that output voltage spec to confirm it's low...
Good luck and report back what you find...
Last edited by hattitude; Apr 23, 2023 at 10:50 AM.
Seasoned HDF Member
Joined: Mar 2010
Posts: 38,537
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From: Honah Lee
Been on a trickle charger all night, shows 12.8 volts at stand by (surface charge worn off, no load on battery such as key switch on). Can't get it load tested today, everything is closed. Can someone explain to me why I am not getting 12 volts from the bcm to the exciter wire when start button is pressed? Am I wrong to assume it should get 12volts? At less than 2 volts, I don't think that would be enough for the the solenoid to pull the contacts together, in turn sending the 12volts from battery to the starter motor
Now some of the ECM and BCM take offs are low voltage. I thought the ECM was still providing a ground circuit for the relay that fed the battery voltage to the solenoid coil. Coming from that closed relay is battery voltage.
The reason I thought it was the ECM is it monitors the CSP before switching on fuel pump full on and allowing spark on coil.
I thought BCM was body. ECM engine.
Never delt with BCM on a bike. Now I have with ECM and especially cars.
Last summer spent hours checking one out that occasionally did not run fuel pump. The ECM control was similar to your delima. I had two grounding circuits coming out of it. One for spark. One for fuel pump.
Occasionally, the fuel pump one had nothing. Obviously something internal in ECM. I fixed it by hardwire jumping the relay when key was on.
No one had ECM for the old vehicle.
Last edited by Jackie Paper; Apr 23, 2023 at 10:03 AM.
Seasoned HDF Member
Joined: Sep 2017
Posts: 12,233
Likes: 4,943
From: England
First up with B2112 always present you have a fault that needs fixing. Just changing or charging the battery is not going to fix that.
Details from a FSM here - https://www.hdforums.com/forum/milwa...l#post20745463
Details from a FSM here - https://www.hdforums.com/forum/milwa...l#post20745463
Seasoned HDF Member
Joined: Mar 2010
Posts: 38,537
Likes: 6,412
From: Honah Lee
Post 13 is your answer to your and my questions.
And I missed error came back. Sorry. You even broke up your post to help reading and I still missed it.
And I missed error came back. Sorry. You even broke up your post to help reading and I still missed it.
Last edited by Jackie Paper; Apr 23, 2023 at 10:28 AM.
Stellar HDF Member
Joined: May 2017
Posts: 2,820
Likes: 6,135
From: Southern NH
More than likely you have a short somewhere that tripping the BCM.
Had this happen before and found a pinched wire on front left turn signal.
Start by checking all electrical features and see if something doesn’t work.
Had this happen before and found a pinched wire on front left turn signal.
Start by checking all electrical features and see if something doesn’t work.
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