Topic: General relay question

[AlekStooge]

Hi, I'm using a mini push button as a horn switch and it requires a relay.

I have 87 going to the actual horn and I took a second look realizing it might go to the push button instead. The other wire on the button is a ground, which I have going to a ground junction and then to 85 on the relay.



Is 87 supposed to go to the horn or does it go to the button?

[OldSchool_IsCool]

Button on 86
Horn on 87

[PeWe]

Do not forget a fuse between the battery and 30. Hanging fuse as close as possible to the battery. This to ensure fuse also will protect an eventual shorted wire against ground. Use wire with thick insulation.
My K6 is a real relay bike.
3 Relays for headlight, HI, LO + relay that switch off parking when LO relay activates to ensure better light pattern.
Relay for Ignition coils power
Relay for horn. It (Dual snail horns) did not work with std wiring that now activate relay only.
All relays are actuated by the std wiring and get their feed direct from battery via hanging fuses of 5-10A. Thick wire connected on the incoming on starter relay and from battery too. I use thick wire with good insulation. Something like 1.5-2.5mm2.
Headlight relays share same fuse. Horn and ignition have separate. LED charging indicator own fuse. I might update the diagram gor the K6.

Wiring otherwise std. One detail that can cause a black and stopped bike is the brake light switch to brake pedal. It is fed by black (main fuse 15A), when this is shorted against frame or engine bike will stop direct. I have got that problem due to a cheap aftermarket brake light switch where the harness bullet plug insulation glided off down the wire and could short against engine when braking. I have not fixed that one yet (fuse). It needs an own hanging fuse of 5A. (Smallest auto fuse I have seen)

[AlekStooge]

Could we say that the wire from the button goes the 86 and comes out 87 then goes to the horn?

PeWe, 30 is fused close to the battery but it is not a hanging fuse it's a box

[bryanj]

87 to horn and if button is grounded the other side, connect to 85

[Bodi]

Depending on the model the horn may have switched power or switched ground. Switched ground horn button is not so easy to add a relay to.

[AlekStooge]

1978 CB 550K USA... as far as I'm aware.



I'm going to hook up one wire from the button to a ground junction and then to 85. The other wire at the button I will hook up to 86.  As for the horn I will plug in 87 and a power wire.

[PeWe]

Could we say that the wire from the button goes the 86 and comes out 87 then goes to the horn?

PeWe, 30 is fused close to the battery but it is not a hanging fuse it's a box

Fuse independent of model is OK.
My K6 has a stock fuse box with 3 fuses only feeding the stock harnes. The biggest consumers now fed separate with own fuses via the relays.

I use LED H4 front that relieve the Amp consumption and ensure charging voltage to battery. 30W instead off 55/60W make a huge difference.

My stock CB750 K2 has no relays (yet), LED H4 reduced amps over the weak constructed bar switches and the only fuse existing, 15A. The voltage supervising LED had an own fuse beside the battery... Ign switch is NOS Honda.

The cheap aftermarket ign switch on my K6 was the start going relays since I read on this forum that it could be weak, not supporting the current melting wire or its connector.

[Bodi]

"87 to horn and if button is grounded the other side, connect to 85"

The pretty much makes the relay pointless as all the horn current will still go through the switch.

[bryanj]

Bodi 85 and 86 are the operating coil whilst 30 and87 are load according to the diagram at start of post

[AlekStooge]

Bodi 85 and 86 are the operating coil whilst 30 and87 are load according to the diagram at start of post

That makes sense

[AlekStooge]

I tested the horn, it didn't work. 

I check the battery 12.3 volts, I check the horn it works.

I started checking continuity

-Ground from the post to spade terminal leading into 85, good.
-Positive post to spade terminal leading into 30 (fused), good.
-86 can't really test it (It goes to the button)
-87 spade terminal to horn, good.
-Positive post to horn, good.

I pulled the relay apart that was a drag Not sure what to do with this.


Last, I wanted to pull the button out of the handlebars. I had to pull out a few terminals at the ground junction to get to it and the main crimp broke at the junction. I don't have anymore so I have to order them. The solder at the button looks okay I can't see it to well because of the heat shrink.

Just a recap. I have as follows:
85-to ground junction and a wire to the button
30-to fuse then to battery
86-to button
87-to horn
+ power to horn

What now?

[jgger]

This is the way that I see it from the instructions. If the horn button works as a grounding switch it won't work.  It must send power to the relay to activate it. But others much smarter than me can verify or wave the B. S. flag.

Reading comprehension is a must..........use terminal 87-not 87a.......Doh! I just saw my stoopid mistake.

[bryanj]

If you put in a permanent, fused, power lead to the coil  you can put a switch in the ground wire of the coil and it will work exactly the same.

[Deltarider]

If you put in a permanent, fused, power lead to the coil  you can put a switch in the ground wire of the coil and it will work exactly the same.

That's what I did. You may need a 15A fuse (my Voxbells draw 10A for their 115dB Guzzi sound).

[bryanj]

That is ok for the load fuse but way too high for the coil fuse which should be less than 3amp.

EDIT

You need two seperate fused supplies
(1) a high fused one for the "load" in this case horn
(2) a low fused one for the coil(switched circuit)

[AlekStooge]

"If the horn button works as a grounding switch it won't work." Are you saying I should send a power wire to the button and keep 86 going to it as well, and have 87 going to horns well as a power wire correct?

[Deltarider]

My horn switch is ofcourse fused by the original main fuse, the 'load' has an extra 15A fuse in it's line between the starter solenoid and the relay.

[bryanj]

Going back to the original question and ignoring everything inbetween

Horn does go to 87 and if one side of button is grounded connect button to either 85 or 86 with a low rated fused supply to the other.
Large rated fused supply to 30

[Deltarider]

1978 CB 550K USA... as far as I'm aware.

Year is irrelevant. To identify, compare engine- and framenumber to those listed here on p.4 http://www.honda4fun.com/pdf_parts_list/pdf_spac500-550/CB500-550_K3-K4.pdf
Then, as horns were wired differently*, go to the wiring diagrams here: p.182-4 https://www.classiccycles.org/media//DIR_1653304/DIR_1653404/DIR_1653507/ecc6759db0a214d5ffff8825ffffe41e.pdf  to find out which scheme is applicable for your specific model. (This is step one.)
* Some markets had the POS switched, others the NEG.

[AlekStooge]

Going back to the original question and ignoring everything inbetween

Horn does go to 87 and if one side of button is grounded connect button to either 85 or 86 with a low rated fused supply to the other.
Large rated fused supply to 30

87 does go to horn, 85 goes to the button and is grounded and 86 goes to button but it is not directly connected to fused power. 30 however is connected to fused power. Are you saying I should connect fused power to 86 as well?

[bryanj]

If you want it work on a grounded botton yes, you are saying you have two operating buttons at present, if that is true you would need to press both together to make it work.

[AlekStooge]

Only one button which has two wires. I thought the button has to be grounded instead of the horn.

[jgger]

Turn the key on and check both wires for voltage with the button not pushed and again with it pushed. That will tell you what you're working with. If power goes through the button, wire it like the pic I posted EXCEPT use 87 to the horn (not 87a) .

[AlekStooge]

Turn the key on and check both wires for voltage with the button not pushed and again with it pushed. That will tell you what you're working with. If power goes through the button, wire it like the pic I posted EXCEPT use 87 to the horn (not 87a) .

                                                                                                 
Ok will do. I don't know how because I have these wires in locking terminals. I guess I figure it out once I'm in front of it. I have it hooked up the way you said.

I tried to measure volts but I wasn't able to with the relay connected. However, even through the solder and heat shrink I did manage to measure continuity from the button to the locking terminal for ground and the wire going to 86. Both good. Here is what I'm working with. How would I measure volts?