Topic: Location of flasher relay 4 my 78 CB550?

[clzay]

I searched the forums for the location of this, and came up with different locations and styles? Some people say its rectangular, some say its shaped like a beer can? Wanted to see if anyone knows the exact location (wire colors) where to find my relay on my 78 CB550? Sorry I'm a newbie to this... thanks for any help.

[Jonesy]

The shape can vary depending on if the relay is the original one or not..

Remove the left-hand sidecover. Under the starter solenoid you will see a rectangular (if the original) relay with 2 wires attached and it will be suspended by a rubber strap. The box will read "SIGNAL-STAT" on it. If the relay was previously replaced, it will likely be a round can. A 2-prong flasher relay for 3 bucks at the auto parts store will work just fine (unless you really wanna shell out 40 bucks for one at the Honda stealer..).

[TwoTired]

Jonsey types faster than I do.  Here is a supportive viewpoint.

If yours is still stock, it is under the left side cover, rectangular and has two wires attached to it Black and Grey, with a green unconnected one nearby.

Some put automotive ones in there and these are usually cylindrical.

Cheers,

[clzay]

wow... thanks. Thats what I needed. Its the rectangle one and does say signal-stat. I would of never found it. I just pulled it out to try an find one at my local parts store. Thnaks again

[HowardRoark]

I just recently replaced mine too, I bought one at Shucks that looks like this:

http://www.partsamerica.com/ProductDetail.aspx?mfrcode=TRD&mfrpartnumber=552&parttype=121&ptset=A

I don't think I got the same brand, though.  Just get the nice generic one and it works great - or at least it won't blow up for the next 5 rides.  I haven't gone on the 6th yet...

[clzay]

ha ha... sounds good I'll look for something similar. Thanks everyone for all the fast replies!

[Jay B]

with a green unconnected one nearby.

Cheers,

My 350f has that green wire also. I scratched my head a while thinking something was ungrounded, but everything worked. Is that wire ever used???

[KB02]

I have the same question on 750. The PO had replaced the relay once before with something out of a parts store and has two wires plugged in with that green wire just hanging on for the ride. The flashers have always been slow to engage and I thought that maybe by repacing it with a three pronged unit from the parts store that would make the flashers work a little better. Can I do this? Should I? What does that little green wire do?

I tried tracing it out on a wiring diagram, but finding a diamgran that acturately depicts a 1976 CB750F is damned near impossible... or so I have found.

[Jonesy]

There was a thread about this recently. When the bikes were new, that green wire wasn't hooked up to anything. You can use the green wire for connecting an electronic flasher relay with no problems.

[TwoTired]

Yep, what Jonsey said.  I would add that that green wire is attached to frame ground or battery minus.  Electronic flashers usually need this connection, the stock bi-metalic strip type did not, so only two connections were used.

Now who wants to know how bi-metallic strip flashers function?

Cheers,

[Jonesy]

Now who wants to know how bi-metallic strip flashers function?

Let me guess.. the same way blinking Christmas lights do. The bimetallic strip carries the current from one terminal to the other. The current heats up the strip and being made of a bimetallic construction, it bends away from the terminal, breaking the circuit. Then, with current no longer flowing through it, the strip cools down, bending back and reconnecting the terminals. This cycle repeats until you cut the power to the turn signals.  (Do I graduate? )

Now, what I REALLY wanna know is why do Honda wiring harnesses have a spare green and a spare hot wire terminal just dangling in the electrical compartment? Did the serve some kind of diagnostic funtion, or a quality control test point during wiring harnes and/or bike production?

[SteveD CB500F]

You go to the top of the class Jonesy.

I was just explaining this to Jim Shea in the pouring rain outside a Honda dealer in Slough (UK) last weekend.

His relay CB750F1 1976 had three prongs but even when all connected it still wouldn't work!

[TwoTired]

Now who wants to know how bi-metallic strip flashers function?

Let me guess.. the same way blinking Christmas lights do. The bimetallic strip carries the current from one terminal to the other. The current heats up the strip and being made of a bimetallic construction, it bends away from the terminal, breaking the circuit. Then, with current no longer flowing through it, the strip cools down, bending back and reconnecting the terminals. This cycle repeats until you cut the power to the turn signals.  (Do I graduate? )

Now, what I REALLY wanna know is why do Honda wiring harnesses have a spare green and a spare hot wire terminal just dangling in the electrical compartment? Did the serve some kind of diagnostic funtion, or a quality control test point during wiring harnes and/or bike production?

I'll have to give you a B because you didn't mention why the bi metal bends.  Metals have different thermal coefficients of expansion.  When you laminate two metals and heat them, one of the metals expands more rapidly than the other, thus causing the bending effect.  Cool down is the reverse, of course.  Sometime the flasher bi-metal strips are convex and/or concaved shape which allows them to snap into and out of position with the heat/cold cycle.  Anybody remember those jumping frog toys as a kid.  Press in the little dome (heated by your body temp)  Set the little frog down and wait.  When the metal cooled down, snap, and the frog jumped.  You mean nobody else had to investigate why this worked?  


I'm only aware of the dangling green wire, which I assumed was a hedge against the low voltages the bike can acheive if it idles too long with a depleted battery.  Customer complaints about signal flashers can be easily addressed in the field, by puting in a flasher that wasn't sensitive to voltage fluctuations and higher wattage bulbs.  It's easier and cheaper to address such issues on a small case by case basis than put a much more expensive flasher in the entire production fleet.

What Hot wire are you refering to?

[Jonesy]

Geez, TwoTired- I didn't realize you wanted a doctoral dissertation!   I never heard of one of those frogs.... I thought that's how household thermostats worked.

On my 750 there is the usual spare green ground connection, and there is a red wire with a female blade terminal. My guess is it might be some kind of leftover from the K0-K2 models which only used the single fuse... but this red wire is to thin a gage to carry the entire 15 amps for the whole bike.

[HowardRoark]

The bimetallic strip/different coefficient of expansion is how toasters turn off too. 

You guys are awesome - talking science is fun.  The bike is so logical, I love it.

[TwoTired]

On my 750 there is the usual spare green ground connection, and there is a red wire with a female blade terminal. My guess is it might be some kind of leftover from the K0-K2 models which only used the single fuse... but this red wire is to thin a gage to carry the entire 15 amps for the whole bike.

Oh the 750.  Yes, the schematics show a red wire dangle, too.  That's hot right off the battery.  Probably for burglar alarm power.   Or, the cigarette lighter option.

The Cb550s don't have that red one, just the green for the flasher.  About that, I was thinking the Non-North American models may have had different flasher loads that mandated the three prong flashers, or perhaps police models.  Police love lots of flashing lights.  Maybe the same harness was common to all models?

I'm just guessing...

Cheers,

[Kelvin8]

Of couse all this becomes academic when we replace all our running lights with LEDs and need an electronic flasher unit because the LEDs don't draw enough amperage to operate a thermal (bimetal) flasher unit.

[hansi]

Replaced regulator rectifier with new one that supports newer batteries and leds etc. the problem is the unit plugs into the flasher wiring wiring. Does this mean there’s a built in flasher on the r/r unit? Seems unlikely

[bryanj]

The UK law specifies the number of flashes per minute required so a more expensive flasher can that needs a ground is used(the small beer can shape) along with a different rubber mount.
US have different laws and use the cheaper small box bi-mettallic strip type in a small rubber mount.

[Little_Phil]

Are you sure it is the flasher wiring? The modern rectifier/regulator is replacing two separate units on you bike. The rectifier has a multipin connector and the regulator three separate wires.

[hansi]

Are you sure it is the flasher wiring? The modern rectifier/regulator is replacing two separate units on you bike. The rectifier has a multipin connector and the regulator three separate wires.

im going with no, I’m not sure, but it was where my flasher used to live (left side panel) and I can’t seem to locate where the flasher wiring would be

[hansi]

Are you sure it is the flasher wiring? The modern rectifier/regulator is replacing two separate units on you bike. The rectifier has a multipin connector and the regulator three separate wires.

im going with no, I’m not sure, but it was where my flasher used to live (left side panel) and I can’t seem to locate where the flasher wiring would be

fairly sure I found it. I was looking for misc bits in my tool shed and realized that I had unhooked the flasher relay and kept the wiring. Just two bullet connectors on one end so it’s probably just on the harness unconnected. Yay

[Little_Phil]

Your bike may not be standard. The flasher relay wires are black and gray and have female spade connectors.

[hansi]

Yeah but this is what my regulator rectifier upgrade has plugged into. So now there is no place for the flasher

[Bankerdanny]

Yeah but this is what my regulator rectifier upgrade has plugged into. So now there is no place for the flasher

Your combined reg/rec should not use any of the wires that are for the flasher. If it did then you have it wired wrong. You need to add some photos of the wires under your left side cover.

[hansi]

Yeah but this is what my regulator rectifier upgrade has plugged into. So now there is no place for the flasher

Your combined reg/rec should not use any of the wires that are for the flasher. If it did then you have it wired wrong. You need to add some photos of the wires under your left side cover.

yes, this is the conclusion I came to today. It was totally wired wrong. I forgot to remove the OLD regulator and attach the new wires to the harness where the old one was removed. I feel SUPER dumb, but it's sussed out now. Now i just have to figure out how to properly wire the turn signals...for some reason they just turn on and don't flash...

[Bankerdanny]

Are you using regular bulbs or LED

[hansi]

LEDS

[bryanj]

Then you need a special led flasher unit and if you have only 1 repeater bulb dont wire it up

[hansi]

Got one of these but do I need a different one u think?
https://4into1.com/12v-electronic-turn-signal-flasher-relay-led-2-prong/

[hansi]

Then you need a special led flasher unit and if you have only 1 repeater bulb dont wire it up

sorry but I’m not sure what you mean by not wiring up a repeater bulb

[bryanj]

On the arly fours there is a dash panel with oil, neutral.flash, main(red,green,yellow,blue) the yellow indicator repeater has 1 wire to each side indicator and if you connect it with led bulbs all 4 will light up whichever way you put the switch

[hansi]

Duuuuude. You just solved my issue. I was wondering why it was doing that. Thanks!!!!

[Bodi]

The signal lamp on the idiot light panel is wired ... oddly? ... when there's only one. Some bikes (ie 400-4) have two, one for each direction.
With one, they wire the indicator between the two signal circuits. So when one is on, it powers the other side through the tiny indicator bulb. That bulb only takes a tiny current compared to the two signal bulbs so it lights up bright while the signal lamps barely warm up, they don't light at all.
With LEDs that little bulb easily passes enough current to light the two LEDS in the signals, but not enough to light itself. So all four signals light up when flashing but not the indicator (maybe very dimly).
Two fixes:
1- add load resistors to the signal circuits. This lets the electromechanical OEM flasher work normally as there's enough current to make it flash, and the indicator will work as expected.
2 - add two diodes (ie IN4000) in the idiot light circuit, grounding one wire from it and having the two diodes inserted in each wire from the signals connecting to the other wire to the bulb, each diode with its ring end pointing towards the idiot light. You will need either an "LED flasher" - expensive usually from bike shops - or a cheap Autozone electronic 3 terminal flasher with a ground terminal. Note there are other types of 3 terminal flashers with no ground terminal which will just blow your fuse if tried.
If you're trying to save power and improve charging: LED signals aren't going to do much at all. You'll only be saving power while signalling when the signals are flashed on.  What's that? 0.0001% of riding time? So the load resistors won't hurt your charging. If you really like the instant on and instant off flashing with LEDs that may be more attention grabbing, either the resistors or the diodes will work for you. The front marker lights going to LED will save power as they're on whenever low beam headlight is on.