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1Back to top Go down    Rebuilding K75 electrics woes. on Wed Aug 22, 2018 6:05 pm

edmundf

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So,

Trying to rebuild the electrics on this K75, getting precisely nowhere so any thoughts would be appreciated -


I got the bike as far as the starter turning over. I then went to reinstall the radiator / pipes etc. Once that was done i turned on the bike again and noted that the gear selector was not working nor the neutral light or the oil light. Basically the right hand side of the instrument cluster was dead. This also included the starter. I did find a relay fused open (load shed) which i replaced. So far i have checked
- all the fuses
- all the connections at the back of the console
- every damn relay
- stripped and rebuilt the right hand handlebar switch-gear
- clutch switch

The switches on the right hand side are working - turn signal (including the green indicator on the RHS of the cluster) turn cancel, light switch. I checked the starter relay and i am not getting any voltage at the input pins. i am hesitant to short the relay to see if i can get the starter to turn.

I am hoping that someone might have an idea where to start trouble shooting - i got as far as pulling the plug from the electronic ignition module (i am trying to following the guide here http://www.kforum-tech.com/electrical/EFI/bike-wont-start-EN.htm) and could not see any voltage at pin 6 or 11.

Any thoughts on where might be the next best place to continue troubleshooting?

cheers

Ed

    

2Back to top Go down    Re: Rebuilding K75 electrics woes. on Wed Aug 22, 2018 8:47 pm

Laitch

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You seem to be describing a K75 with its shutoff (kill) switch activated. Is the lever in its vertical position? That's its start-enable position. Is 12V being received by it? Is 12V being output from it in the vertical position?


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1995 K75T 68,000 miles
    

3Back to top Go down    Re: Rebuilding K75 electrics woes. on Wed Aug 22, 2018 8:53 pm

D'Ecosse

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Does your rear brake-light work?

(First turn on the Key and set the Kill/Run to Run)

Take your Voltmeter and connect the black probe to battery negative (ground) and leave it there

Using the Red Probe, with Fuses still in place, touch it to the exposed metal tabs on each side of the top of the fuse

Use this method to check the voltage on BOTH sides of Fuse #1

If you get no voltage on EITHER side, then no power from the Kill/Run switch

If you get voltage on one side and not the other, the fuse is blown

If you get voltage on BOTH sides, that confirms the Green/Black power circuit that feeds the instrument panel is good (and your brake light should work)

(Different bike model in image below but principle is the same)

    

4Back to top Go down    Re: Rebuilding K75 electrics woes. on Thu Aug 23, 2018 4:04 am

edmundf

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Thanks for the advice @Latich, @D'Ecosse. I will have another go at it this evening. I did notice that neither brake levers were activating the rear brake light. I did do a contunity check on the kill switch, which seemed to be working. I did suspect it was the kill switch thus me stripping and rebuilding it.

I did not check for voltages at the fuses. That seems a simple place to start so I will check that tonight.

I am understanding that the kill switch will output power to fuse one. If there is voltage at both sides of the fuse where would be the next port of call to test?. Also dumb question of the morning, fuse one = the top fuse?.

Another thing I noted, the load shed relay, that is normally energised?. When I press the starter button it should 'de-energise' ?


Thanks

Ed

    

5Back to top Go down    Re: Rebuilding K75 electrics woes. on Thu Aug 23, 2018 7:24 am

Dai

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Load shed relay: that is correct. When you turn the ignition on there is a direct feed from the battery via the red and green wires on the ignition switch to pin 86 on the LSR. The other side of the coil (pin 85) earths through the starter motor windings (hence a bad earth here causing all sorts of grief elsewhere). Once you hit the start button, the 12 volt feed that goes to the starter motor is also applied to pin 85 on the LSR and it drops out (no more earth).

When you release the starter button there is a delay while the residual voltage in the starter motor windings disappears to earth. Once this has happened, LSR pin 85 can earth again through the windings and the LSR pulls in. The time taken for the residual voltage to go away is the time period between you releasing the starter button and the lights coming back on.


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'83 K100 upgraded to K100RS spec
Others...
'78 Moto Guzzi 850-T3, '79 Moto Guzzi 850-T3 California,'93 Moto Guzzi 1100ie California,
'03 Suzuki Blandit GSF600SK3 (NFS any more because wifey has claimed it)
    

6Back to top Go down    Re: Rebuilding K75 electrics woes. on Thu Aug 23, 2018 7:37 am

edmundf

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Thanks @Dai,


That's what i figured - i am slowly learning Smile. At the moment precisely nothing is happening when i press the starter button. With the symptoms of the brake light not working and the instrument clusters not working it seems that there may be something going on with my kill switch?. This is from what i have learned from the responses above.

My plan of attack is to see if i am getting power to fuse one - if not then it is the kill switch and i will try to trace back that wiring and see if i can see a problem. if there is power to both sides of fuse one I am not sure where to go from there - i will try to follow the wiring on from there and see if there is a break. It could be possible that there has been a wire or socket dislodged that is going into the relays?.

I must go and get another battery for my multimeter - i think that will be the next damn thing to stop working.

Ed

    

7Back to top Go down    Re: Rebuilding K75 electrics woes. on Thu Aug 23, 2018 9:03 am

Laitch

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@edmundf wrote:I did suspect it was the kill switch thus me stripping and rebuilding it.
What was needed to rebuild it?


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1995 K75T 68,000 miles
    

8Back to top Go down    Re: Rebuilding K75 electrics woes. on Thu Aug 23, 2018 9:08 am

edmundf

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I had the 'old' one - the replacement switch was a bit gummy so i took it apart and cleaned it out. I figured that there was a bad contact someplace. The switch was disassembled to component parts, all the copper contact pads cleaned and reassembled. The switch mechanism is much crisper now.

    

9Back to top Go down    Re: Rebuilding K75 electrics woes. on Thu Aug 23, 2018 9:40 am

Laitch

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@edmundf wrote:I had the 'old' one - the replacement switch was a bit gummy so i took it apart and cleaned it out. I figured that there was a bad contact someplace. The switch was disassembled to component parts, all the copper contact pads cleaned and reassembled. The switch mechanism is much crisper now.when I
You replaced one switch with another that you had cleaned. This guide was useful to me, using Google Translate. Smile Perhaps you used it, too.


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1995 K75T 68,000 miles
    

10Back to top Go down    Re: Rebuilding K75 electrics woes. on Thu Aug 23, 2018 11:46 am

D'Ecosse

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@edmundf wrote:.... At the moment precisely nothing is happening when i press the starter button. With the symptoms of the brake light not working and the instrument clusters not working it seems that there may be something going on with my kill switch?.

Yes, that is why I asked about the brake light, that is another simple quick indicator off the same power circuit on output side of Fuse 1.
And the Start switch won't work unless you have that circuit powered - even discounting the start enable via the neutral enable (which requires the Instruments to be active), if the clutch was pulled that would also couple the Green/Black circuit power (output of Fuse 1) directly to the start switch from output of clutch switch (on Black/Green to the start switch)
So all the evidence points to either simply the Fuse, or more likely the Kill/Run Switch
You can confirm you have power into the switch by checking for 12V on the green wire on the Switch connector

Here is simplified schematic for you



Last edited by D'Ecosse on Thu Aug 23, 2018 5:43 pm; edited 1 time in total

    

11Back to top Go down    Re: Rebuilding K75 electrics woes. on Thu Aug 23, 2018 12:55 pm

edmundf

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Thanks for all the help, hopefully i will find out in a few hours, just have to escape from work first Smile. i will update shortly

    

12Back to top Go down    Re: Rebuilding K75 electrics woes. on Thu Aug 23, 2018 2:40 pm

edmundf

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So home, no voltage at the fuse. Pulled the rh switch off the bike and the instrument panel lit up. Appears I have a break someplace in the loom :/. When I move it the cluster goes out. Move it again and it comes back on. Hmmm. Also no voltage at the starter solenoid, yet.

Investigation continues.

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13Back to top Go down    Re: Rebuilding K75 electrics woes. on Thu Aug 23, 2018 2:57 pm

edmundf

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Success!

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14Back to top Go down    Re: Rebuilding K75 electrics woes. on Thu Aug 23, 2018 5:24 pm

D'Ecosse

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Congrats
So what did you find?

    

15Back to top Go down    Re: Rebuilding K75 electrics woes. on Thu Aug 23, 2018 5:37 pm

edmundf

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I think it was an intermittent connection at the plug for the rh switch gear. Careful cleaning and it seems to be stable now. Tomorrow, air box and then the tank. Perhaps even an attempt to start it!

Thanks again for the help

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