Topic: 1978 Honda CB750F turn signal wiring issue

[sho2k86]

So here is the issue.
When I turn either left or right, the turn signal doesn't flash, stays constant. The running light comes on as usual when I turn the bike on. Also when I unplug the flasher relay, nothing change. Same symptoms. The turn light comes when I turn the L/R switch. That shouldn't happen right? Does that mean, there must be some shorting in the left hand control wiring?

Here is what I have done:
1. Changed to three prong electronic flasher relay (which i hear click when I turn the key on, and also when I turn the L/R switch. But just clicks once)
2. Opened the left control switch and cleaned it really well making sure the contacts were clean.
3. made sure all wiring were connected, and grounds are good.
4. Buzzer is not connected as of now (testing without it)

My lights aren't OEM and doesn't have the bucket ground wire, is that needed?
BTW, all my lights are LED, and I am testing it without connecting the rear turn signal (just front turn signal are connected). Should I test it with all lights connected, does it matter.

Thank you guys for all your help

[Bankerdanny]

Both the front and rear lights need to be connected for it to flash. You also need a solid state flasher that works with LED lights because they don't draw enough power to trip an ordinary flasher.

[sho2k86]

Thank you for the suggestion. I will connect the rear LED sets.
I currently have the following Flasher:

https://shop.advanceautoparts.com/p/novita-led-compatible-electronic-flasher-ep34/5081327-p?c3ch=PLA&c3nid=5081327-P&adtype=pla&gclid=CjwKCAjwrNjcBRA3EiwAIIOvq6Xhwhw63xKgSmQX2dPxtCI38Uk7ZD_s5Ehtj2DPhjEawK6DOj6YNRoCn9IQAvD_BwE&gclsrc=aw.ds&dclid=CJenx8jOsN0CFRGPswodw0MJAQ

Would that be okay?

[Bankerdanny]

That should work.

[sho2k86]

My other question is, should the turn singals come on with no flasher relay connected? Mine comes on with or without flasher relay. Just doesn't flash. If I am right it my thinking, the power is provided to the control switch from the gray wire at the flasher relay, which in turn provides intermittent power to the turn signals, thus flashing.

Thank you once again for such quick response

[calj737]

They will illuminate without the flasher if power is provided. The relay causes the intermittent pulse.

[sho2k86]

thank you guys. I will follow the suggestion and update you guys tonight

[Bodi]

Nope. All signal power comes through the flasher: remove it and they do not light. The lamp current through the original flasher causes the flashing. A 3-terminal electronic flasher (if the right type, some are unsuitable!) works a bit differently but the end result is the same.
The correct 3 terminal electronic flashers should work on just the front signals, even if LEDs. They don't need much current to activate. They will flash at an "alternate rate" if less than two standard signal lamps are connected (filament type), usually a faster than normal flash rate but it can be a slower than normal rate depending on the manufacturer's preference.
Various other 3 terminal flashers have the third wire for an dash indicator light or for a second signal output (for semi trucks or other trailers). These usually just blow a fuse if connected to the bike's flasher ground wire.

[sho2k86]

Thanks for the info Bodi. I was sort of thinking what you just said. That's why I was sort of trying to get some guidance as to what may be the problem. Why is the turn signal light coming on without flasher connected with the black/gray/green wire. Could it be some sort of shorting in the left handle bar wiring running to the headlight bucket?

In the meantime, I will definitely try what Bankerdanny said, just to make sure if that is the case

[Bankerdanny]

Thanks for the info Bodi. I was sort of thinking what you just said. That's why I was sort of trying to get some guidance as to what may be the problem. Why is the turn signal light coming on without flasher connected with the black/gray/green wire. Could it be some sort of shorting in the left handle bar wiring running to the headlight bucket?

In the meantime, I will definitely try what Bankerdanny said, just to make sure if that is the case

Only two wires connect to the flasher: black and grey. Black is power into the relay and grey is power out to the left bar switch for the turn signals. If the turn signal lights up without the relay connected then you definitely have something connected wrong.

[sho2k86]

I will double check, but looks like all the wire are connected correctly, the appropriate running light comes on, the appropriate turn signal comes on with L/R switch (just doens't blink). I will try to post picture of the wiring tonight

[Bodi]

A 3-terminal flasher is pretty much necessary for LED signals unless you add load resistors to draw the current that standard bulbs would. The green wire is used with these flashers. You can get "LED" flashers online but I think these are just normal 3-terminal flashers with the lamp-out alternate flash rate disabled... an auto store one will work OK but flash fast or slow.

[Bodi]

Cjeck the switchpod wiring - if the signals come on with the flasher unit disconnected, somehow the grey wire connection is getting black wire power.

[sho2k86]

Cjeck the switchpod wiring - if the signals come on with the flasher unit disconnected, somehow the grey wire connection is getting black wire power.

Thank Bodi, I am using the following flasher relay

https://shop.advanceautoparts.com/p/novita-led-compatible-electronic-flasher-ep34/5081327-p?c3ch=PLA&c3nid=5081327-P&adtype=pla&gclid=CjwKCAjwrNjcBRA3EiwAIIOvq6Xhwhw63xKgSmQX2dPxtCI38Uk7ZD_s5Ehtj2DPhjEawK6DOj6YNRoCn9IQAvD_BwE&gclsrc=aw.ds&dclid=CJenx8jOsN0CFRGPswodw0MJAQ

This might be a dumb question as I am new to motorcycle, what is the switchpod wiring? The wiring in the left hand control?

[Bankerdanny]

Cjeck the switchpod wiring - if the signals come on with the flasher unit disconnected, somehow the grey wire connection is getting black wire power.

Thank Bodi, I am using the following flasher relay

This might be a dumb question as I am new to motorcycle, what is the switchpod wiring? The wiring in the left hand control?

yes, that's what he meant.

The F models are a little different than the K's because of the triangular plastic box between the front frame down tubes. All the other models have most of the connections for the wires inside the headlight shell, but on the F most of them are in that box. Sometimes they don't get hooked up correctly.

What you describe sounds like the wire that feeds power into the left hand control for the turn signals got connected to one of the brown wires that has power all the time and not the grey wire that gets power from the relay. Find the wire bundle that runs from the bar control through the bars and down to the plastic box and confirm that the grey wire out of the loom is connected to the gray wire to the control.

[sho2k86]

Its raining a little too much here in NY. Put the bike to sleep for tonight. Gonna work on it tomorrow 

[sho2k86]

so the problem persists.
I have done the follow:

1. Connected the rear turn signals (all connected)
2. took apart the left control, and cleaning all contacts with contact cleaner. It was greased but free of rust.
3. Took apart the wiring loom from the left control, looks pretty clean and free of any rusty/water residue.

Put it back all together follow the 1978 Honda CB750F wiring diagram.

I thing improved, the turn signal doesn't come on with the flasher disconnected (which was happening before). That means, now the gray wire is not getting power without the flasher connected.

Currently my battery voltage is 10.8V. Is that too low?

Also, just to confirm I am connecting the flasher correctly, L to gray B to black and optional E to green (for the 3 prong). I have tried both 3 and 2 prong electric flasher relay.

The previous owner upgrade the rectifier to this:

https://www.amazon.com/dp/B01LOYLDXS/?ref=exp_influencer-3f8085ce_lv_dp_vv_d

I am kinda lost now

[Bankerdanny]

I would top up your battery, low voltage like that will keep the blinkers from working properly. While the bike is being worked on and not run regularly you should periodically hook up a battery charger to top off the battery.

Pretty much all the replacement reg/rec combo units look like that one, the only difference is whether they are pre-wired to plug directly into the harness or not.

Based on the diagram you have the 3 prong hooked up correctly.

Do you have a multimeter so you can trace the power flow?

[Bodi]

That looks like it should be a good flasher. B is power, E is ground, L is load/lights.
The problem now is you have power through the flasher to the signals but no flashing? Might be low voltage but I would expect it to work. Can you connect a "normal" signal lamp (filament type) between L and ground and see if that flashes (key on)?
The Grote 44110 LED flasher (just an example) wants 0.25A minimum current, what power LEDs are you using? A 1W LED will be stinking bright and draw about 0.3A but lower power ones could be below 125mA and fail to trigger the flasher.

[sho2k86]

I would top up your battery, low voltage like that will keep the blinkers from working properly. While the bike is being worked on and not run regularly you should periodically hook up a battery charger to top off the battery.

Pretty much all the replacement reg/rec combo units look like that one, the only difference is whether they are pre-wired to plug directly into the harness or not.

Based on the diagram you have the 3 prong hooked up correctly.

Do you have a multimeter so you can trace the power flow?

I started the bike today after almost a month. I had to kick start the bike, as it not no juice for the starter motor. After running it for a while, still same symptoms.

The rectifier unit the previous owner had installed is plug an play pretty much.

I do have a multimeter but have no idea how to use it But will start searching online for guidance on how to use it. But if you could give me some suggestion, I would be really thankful

[sho2k86]

That looks like it should be a good flasher. B is power, E is ground, L is load/lights.
The problem now is you have power through the flasher to the signals but no flashing? Might be low voltage but I would expect it to work. Can you connect a "normal" signal lamp (filament type) between L and ground and see if that flashes (key on)?
The Grote 44110 LED flasher (just an example) wants 0.25A minimum current, what power LEDs are you using? A 1W LED will be stinking bright and draw about 0.3A but lower power ones could be below 125mA and fail to trigger the flasher.

https://www.ebay.com/itm/Motorcycle-Handlebar-Turn-Signal-Grip-Bar-End-LED-Plug-Strobe-Side-Marker-Light/202141361609?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

https://www.amazon.com/gp/product/B0140XMI1Q/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

There are the lights I am running.

I could definitely run one filament bulb between L and ground to see in the flasher kicks on.

Initially when I installed the 3 prong flasher with just front signal light installed, the front signals flashed for a bit when I slightly turned the turn sign switch to left and right, but when I turned all the way to either left or right it would stop and stay constant. This was when mistakenly connected the buzzer wire from the handle bar to the black power terminal. Could this have shorted the flasher unit?

Since then I have corrected the wiring, and left the buzzer wire unplugged. Cleaned every contact throughly. Still no change

[sho2k86]

PROBLEM SOLVED GUYS...

The miss wiring initially must have shorted the flasher and went bad. I realized it as I was writing my last post. I ran to the auto store and picked up same flasher, and wohoooooo... WORKING TURN SIGNAL

THANK YOU ALL SOOOO MUCH

ON side note... any suggestion on converting to LED head light or getting a new assembly? just worried about the bird nest space in the bucket :p

[mtisdall20401]

I had this problem even AFTER REPLACING THE FLASHER RELAY WITH A SOLID STATE ONE. After selecting the light or right signal the indicators would just stay on constantly. The problem turned out to be the halogen light bulb in the turn indicator Light on the handle bar clamp. I replace the single bulb with two 12v leds (one for each individual circuit) and problem solved.


Sent from my iPhone using Tapatalk

[Bankerdanny]

I would top up your battery, low voltage like that will keep the blinkers from working properly. While the bike is being worked on and not run regularly you should periodically hook up a battery charger to top off the battery.

Pretty much all the replacement reg/rec combo units look like that one, the only difference is whether they are pre-wired to plug directly into the harness or not.

Based on the diagram you have the 3 prong hooked up correctly.

Do you have a multimeter so you can trace the power flow?

I started the bike today after almost a month. I had to kick start the bike, as it not no juice for the starter motor. After running it for a while, still same symptoms.

The rectifier unit the previous owner had installed is plug an play pretty much.

I do have a multimeter but have no idea how to use it But will start searching online for guidance on how to use it. But if you could give me some suggestion, I would be really thankful

If you post a picture I am sure we can help you with the basics for your particular meter. Knowing how to use it to test for voltage, continuity, and resistance (ohms) can save you a lot of time in tracking down and solving most electrical issues.

[sho2k86]

I had this problem even AFTER REPLACING THE FLASHER RELAY WITH A SOLID STATE ONE. After selecting the light or right signal the indicators would just stay on constantly. The problem turned out to be the halogen light bulb in the turn indicator Light on the handle bar clamp. I replace the single bulb with two 12v leds (one for each individual circuit) and problem solved.


Sent from my iPhone using Tapatalk

I have a very simple one

https://www.amazon.com/AstroAI-Digital-Multimeter-Voltage-Tester/dp/B01ISAMUA6/ref=sr_1_7?s=lamps-light&ie=UTF8&qid=1536808538&sr=1-7&keywords=multimeter