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1Back to top Go down    Tail light question on Tue Jan 24, 2017 6:40 am

nods

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Hi All,

Quick couple of questions - does the tail light turn off via the load shed relay during starting? I'm looking at the wiring diagram and can't see how it does. Just trying to understand how to re-wire with the Motogadget m-unit and remove the load shed relay.

Am I right to assume the tail light is also the number plate light?

Cheers,
Nods


__________________________________________________
Chassis number0025951
Vehicle code0504
SeriesK589
ModelK 100 RT 84 (0504 ( 0505 )
Body typeK 100 RT 84 (0504
Catalog modelECE
Production date1985 / 01
Engine0514)
Transmission
Steering
CatalyzerNONE
    

2Back to top Go down    Re: Tail light question on Tue Jan 24, 2017 7:36 am

92KK 84WW Olaf

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The tail light unit has two bulbs in it. The lower one is a 10W [cars usually use 5W but you can also get 21W in this size bulb] and it lights the number plate from above, through the clear panel in the underside of the tail light. The upper bulb is clear 21W same as indicators. The bases of all the bulbs are the same but the 21W normally has a bigger glass on it to stop it being 'misused'. If you use the smaller glass 21W bulb in the indicators you then have an emergency spare rear light bulb or brake light bulb.

As far as I know the Load Shed Relay isolates the lighting circuits but to be honest I never checked.


__________________________________________________
1992 K100LT 0193214 101,000 miles
1984 K100RT 0022575 Baja Red bought 36,000 now 87,100 miles
1997 K1100LT 58,000 miles
    

3Back to top Go down    Re: Tail light question on Tue Jan 24, 2017 8:30 am

nods

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Thanks a lot Olaf.

When starting one's bike it's not something that would normally be noticed - whether or not the tail light is turned off along with the head light. Perhaps one of you kind fellows could ask your better half to have a look next time you fire up your brick?

It's not a big deal, more of a curiosity for me and to see if perhaps the BMU is doing some internal switching to turn it off.


__________________________________________________
Chassis number0025951
Vehicle code0504
SeriesK589
ModelK 100 RT 84 (0504 ( 0505 )
Body typeK 100 RT 84 (0504
Catalog modelECE
Production date1985 / 01
Engine0514)
Transmission
Steering
CatalyzerNONE
    

4Back to top Go down    Re: Tail light question on Tue Jan 24, 2017 9:04 am

Inge K.

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nods wrote:- does the tail light turn off via the load shed relay during starting?

Yes.


__________________________________________________
Inge K.
K100RS -86. (first owner), K1100LTSE -94.
    

5Back to top Go down    Re: Tail light question on Tue Jan 24, 2017 11:19 pm

nods

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Inge K. wrote:
nods wrote:- does the tail light turn off via the load shed relay during starting?

Yes.
Thanks Inge, but (dumb question) how?

I'm looking at the early 8 valve wiring diagram, and I can't see how the BMU is being supplied power by the output of the load shed relay. The tail light and stop light are both powered from the BMU from what I can see. The BMU seems to get it's power from the Green/Black wire that comes from the output of fuse #1 which is getting power from the Green/Yellow wire connected to the Emergency cutoff switch and hence the ignition circuit.

Cheers,
Nods


__________________________________________________
Chassis number0025951
Vehicle code0504
SeriesK589
ModelK 100 RT 84 (0504 ( 0505 )
Body typeK 100 RT 84 (0504
Catalog modelECE
Production date1985 / 01
Engine0514)
Transmission
Steering
CatalyzerNONE
    

6Back to top Go down    Re: Tail light question on Wed Jan 25, 2017 4:17 am

charlie99

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hi nods ...
I guess you have to remember a couple of things

generally the system electronics is off one power supply fuse ...im talking about the bmu ..ecu , instruments ..
in addition most of the load type electrics come from a secondary supply ...

I guess this is to isolate systems that need to run all the time ....and loads from those systems that they control

ie two fuses for the bmu ...might mean the bmu needs + supply to work ...but the actual load to the globes is from a second power supply - fuse

I figure that the stuff that needs to run all the time ..is unlikely to fault ...but the things that do fault ..like globe holders, globes . brake switches and all the rest that have wiring outside of the main electronics loom ..will break the main ignition and running systems if they fault ....
far better that the load devices fuse than take down the whole ignition system ...

hope that helps explain something of the way of thinking things through

cheers and good luck


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O
    

7Back to top Go down    Re: Tail light question on Wed Jan 25, 2017 5:02 am

BobT

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Life time member
Best thing to do is throw away the BMU and then fit LED tail lights. I have done that and it is not a big job. You don't need a BMU with LEDs as they are much more reliable than filament bulbs.

    

8Back to top Go down    Re: Tail light question on Wed Jan 25, 2017 5:13 am

nods

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Silver member
Silver member
BobT wrote:Best thing to do is throw away the BMU and then fit LED tail lights. I have done that and it is not a big job. You don't need a BMU with LEDs as they are much more reliable than filament bulbs.
Cheers Bob, that's part of the plan.


__________________________________________________
Chassis number0025951
Vehicle code0504
SeriesK589
ModelK 100 RT 84 (0504 ( 0505 )
Body typeK 100 RT 84 (0504
Catalog modelECE
Production date1985 / 01
Engine0514)
Transmission
Steering
CatalyzerNONE
    

9Back to top Go down    Re: Tail light question on Wed Jan 25, 2017 5:15 am

nods

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Silver member
Silver member
charlie99 wrote:hi nods ...
I guess you have to remember a couple of things

generally the system electronics is off one power supply fuse ...im talking about the bmu ..ecu , instruments ..
in addition most of the load type electrics come from a secondary supply ...

I guess this is to isolate systems that need to run all the time ....and loads from those systems that they control

ie two fuses for the bmu ...might mean the bmu needs + supply to work ...but the actual load to the globes is from a second power supply - fuse

I figure that the stuff that needs to run all the time ..is unlikely to fault ...but the things that do fault ..like globe holders, globes . brake switches and all the rest that have wiring outside of the main electronics loom ..will break the main ignition and running systems if they fault ....
far better that the load devices fuse than take down the whole ignition system ...

hope that helps explain something of the way of thinking things through

cheers and good luck
I think that helps, thanks Charlie Smile

Basically to get rid of the load shed relay I need to turn off non-essential items during start up and ensure items that need power still have it!


__________________________________________________
Chassis number0025951
Vehicle code0504
SeriesK589
ModelK 100 RT 84 (0504 ( 0505 )
Body typeK 100 RT 84 (0504
Catalog modelECE
Production date1985 / 01
Engine0514)
Transmission
Steering
CatalyzerNONE
    

10Back to top Go down    Re: Tail light question on Wed Jan 25, 2017 5:19 am

Inge K.

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VIP
VIP
nods wrote:I'm looking at the early 8 valve wiring diagram, and I can't see how the BMU is being supplied power by the output of the load shed relay.

To add to what Charlie allready said,, the BMU needs a Power supply to function (from fuse 1) .....Power to the tail light just passing through the BMU, and follows this path:
LSR-->light on/off switch-->ignition switch-->fuse 2-->BMU-->tail bulb.


__________________________________________________
Inge K.
K100RS -86. (first owner), K1100LTSE -94.
    

11Back to top Go down    Re: Tail light question on Wed Jan 25, 2017 6:13 am

charlie99

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VIP
VIP
nods wrote:
charlie99 wrote:hi nods ...
I guess you have to remember a couple of things

generally the system electronics is off one power supply fuse ...im talking about the bmu ..ecu , instruments ..
in addition most of the load type electrics come from a secondary supply ...

I guess this is to isolate systems that need to run all the time ....and loads from those systems that they control

ie two fuses for the bmu ...might mean the bmu needs + supply to work ...but the actual load to the globes is from a second power supply - fuse

I figure that the stuff that needs to run all the time ..is unlikely to fault ...but the things that do fault ..like globe holders, globes . brake switches and all the rest that have wiring outside of the main electronics loom ..will break the main ignition and running systems if they fault ....
far better that the load devices fuse than take down the whole ignition system ...

hope that helps explain something of the way of thinking things through

cheers and good luck
I think that helps, thanks Charlie Smile

Basically to get rid of the load shed relay I need to turn off non-essential items during start up and ensure items that need power still have it!



I think your getting the picture mate

so worst case scenario ..headlight on .(including rear lamps and all the rest - non essentials ) can wink out whilst start procedure is occurring ...saving in some cases 7- 15 amps ...which could be better used for cranking the motor ...with minimal voltage drops to the ignition "must haves " eg ignition coils ..fuel pump ecu , etc
cheers mate


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O
    

12Back to top Go down    Re: Tail light question on Wed Jan 25, 2017 6:29 am

nods

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Silver member
Silver member
Inge K. wrote:
nods wrote:I'm looking at the early 8 valve wiring diagram, and I can't see how the BMU is being supplied power by the output of the load shed relay.

To add to what Charlie allready said,, the BMU needs a Power supply to function (from fuse 1) .....Power to the tail light just passing through the BMU, and follows this path:
LSR-->light on/off switch-->ignition switch-->fuse 2-->BMU-->tail bulb.
Thanks for taking the time to explain that to me Inge - makes sense when someone spells it out. Apologies for not seeing that path - that's the one I was wondering about.


__________________________________________________
Chassis number0025951
Vehicle code0504
SeriesK589
ModelK 100 RT 84 (0504 ( 0505 )
Body typeK 100 RT 84 (0504
Catalog modelECE
Production date1985 / 01
Engine0514)
Transmission
Steering
CatalyzerNONE
    

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