Author Topic: Headlight relay where did I go wrong.  (Read 6658 times)

Offline Martin

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Headlight relay where did I go wrong.
« on: January 16, 2016, 10:27:05 AM »
1.00 am OZ time can't rattle around in workshop as it is next to bedroom. As I was removing fairing to get damage repaired due to bike wishing to take a nap. I decided to fit long overdue headlight relay ( I've had it on my list to do for the last 16 years ). I wired up the new 5 pin relay as follows, heavy duty 25amp wire from battery pos + fused to relay terminal 30 under fairing, 25amp wire from battery neg - to terminal 85, wire from existing headlight socket high beam to terminal 86, wire from terminal 87 to new ceramic headlight socket high beam, wire from terminal 87A to new headlight socket low beam, extra earth wire from terminal 85 to earth on new headlight socket. The end result really good light from high and low beam but when I turn off bike headlight still on. It has left me scratching my head, but as I can't go in workshop until morning where did I go wrong. In the light of day It might come to me.
Perplexed Martin.
  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline The Mighty Gryphon

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Re: Headlight relay where did I go wrong.
« Reply #1 on: January 16, 2016, 10:33:31 AM »
Martin, having wired the relay directly to the battery, there is nothing to turn off the headlight.  The five terminal relay you are using has a form C contact, that is, that there are two positions for the output and that one of the positions is always going to be connected. 

What you needed to use was a pair of NO(normally open) relays, one for each beam.  Each relay will be activated by the power from the hi/lo switch on the bars.  That is how Eastern Beaver does it.
  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

Offline Martin

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Re: Headlight relay where did I go wrong.
« Reply #2 on: January 16, 2016, 10:40:42 AM »
Double Duh thanks Gryph, never used the 5 pin relay before, was trying to be smart and do it with one relay, and outsmarted myself ( not hard to do ). Will redo in the morning, I will see the light.
Thanks Martin.
  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline The Mighty Gryphon

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Re: Headlight relay where did I go wrong.
« Reply #3 on: January 16, 2016, 10:51:27 AM »
Go forth from the darkness...
  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

Offline Martin

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Re: Headlight relay where did I go wrong.
« Reply #4 on: January 16, 2016, 11:08:55 AM »
Gryph this is the diagram I used of the internet from Adventure riders. Didn't really think about it .
 Thanks Martin.
  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline Martin

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Re: Headlight relay where did I go wrong.
« Reply #5 on: January 16, 2016, 11:29:21 AM »
Gryph tried to go fourth but tripped over a bucket and came fifth. I had a look at the diagram that I posted it's a bit hard to read Top LH 30 Pos from battery, bottom LH headlight switch, bottom RH 12v Neg  87 to Hi 87A to Lo. I now see the light it was never going to work.
Thanks again Martin. PS how's the bolt progressing or is it too cold to do anything.
  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline Inge K.

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Re: Headlight relay where did I go wrong.
« Reply #6 on: January 16, 2016, 12:04:34 PM »
You can use your setup as is, but you have to add one relay more in the circuit.
This relay you must put between your relay and the battery, and using switched
power as signal....then the light goes off when you turn off the ignition.

30: battery +.
85: ground.
86: switched power.
87: to existing relay 30 terminal.
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Offline rbm

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Re: Headlight relay where did I go wrong.
« Reply #7 on: January 16, 2016, 01:30:52 PM »
Schematic for BMW headlight relay circuit.  This is the schematic details the modification to which Inge refers.
  • Regards, Robert
Toronto, Ontario

1987 K75 - Build Blog @http://k75retro.blogspot.ca/

Offline Inge K.

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Re: Headlight relay where did I go wrong.
« Reply #8 on: January 16, 2016, 02:34:07 PM »
This is the schematic details the modification to which Inge refers.

Nah, the same relays is used, but the circuit I have in mind is much more simpel.
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Offline The Mighty Gryphon

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Re: Headlight relay where did I go wrong.
« Reply #9 on: January 16, 2016, 04:13:17 PM »
Inge has it right.  Just add a second relay to kill the power when the bike is shut down.  The signal for the second relay only needs to be taken somewhere downstream of the load shed relay so as to not have the headlight on when starting.

Regarding the bolt, check the what did you do thread.  I'll be posting there shortly.
  • In my garage in Marilla, NY
  • '91K100RS White/Blue
Current:
'91 K100RS16V "Moby Brick Too"

Past:
'94 K75RT "Ilsa, She Wolf of the SS"
'92 K100RS16V "Moby Brick" (RIP, deceased in a vehicular assault)
'94 K75S Special Edition Dakar Yellow "Cheetos"
'89 K100RS Special Edition "Special Ed"

Offline rbm

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Re: Headlight relay where did I go wrong.
« Reply #10 on: January 17, 2016, 11:26:33 AM »
Guys, That's exactly what the schematic shows.  It looks complex because it's including relevant parts of the bike's wiring harness for context.  The essence of the circuit is the two relays; the SPST is the switched power and the SPDT is hi/lo beam select.  The diodes are optional; used as suppressors.
  • Regards, Robert
Toronto, Ontario

1987 K75 - Build Blog @http://k75retro.blogspot.ca/

Offline Martin

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Re: Headlight relay where did I go wrong.
« Reply #11 on: January 17, 2016, 01:23:15 PM »
Thanks for all the input, once Gryph posted, I immediately saw what I did wrong. I don't know why I didn't see it when I sketched the diagram off the internet ( Senior moment I guess ) :dunno. I am dropping off the belly pan and right hand fairing this morning for repair, they have told me I will get it back on Thursday. Which seems really quick, we'll see. As per my other post I am still tossing up how to treat the belly pan for chip protection, will probably run without belly pan until I decide. Once I've dropped off the wife I am going to wire in the second relay as per RBM. I was really impressed by the amount of light the relay releases. 
Thanks to all Martin. :clap:
  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

Offline Martin

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Re: Headlight relay where did I go wrong.
« Reply #12 on: January 23, 2016, 07:37:43 PM »
Second relay fitted can't try out on the road yet, still waiting on fairing, belly pan repaint. I thought four days was a bit quick, repaint date now Thursday. I did try out light in a darkened garage, so far I am happy with the improvement, but the real test will come when I am back on the road. I am now starting to suffer from withdrawal. I don't know how you guys cope with the winter lay offs. Even when I lived down south in Victoria, you had to head to the mountains to find snow, and you could still ride all year round.
Thanks to all for the input Martin.
  • North Lakes Queensland Australia
  • 1992 K75s Hybrid, Lefaux, Vespa V twin.

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