Lights Out!

[Solina Dave]

i have a question, and I'm not sure if the answer is so simple that I should feel embarrassed, or not. But here it is anyway.
I of course, have a single 12 volt feed to my taillight that comes on with the ignition switch. I split that single feed to power two more taillights. Now I have one feed powering three taillights. I want to install a warning light on my dash that will come on automatically, if I lose the 12 volts where the single feed splits, and all three lights go out. I just wish to monitor the taillights only, and only if all three taillights go out. I won't monitor the brake lights or turn signals. I'm sure that relays would come into play here, but I'm not sure which relays or how they would be wired in. any suggestions would be welcome. It's a '78 GL1000, not that it matters much in this case.

Thanks...........................Dave

[SnoBrdr]

i have a question, and I'm not sure if the answer is so simple that I should feel embarrassed, or not. But here it is anyway.
I of course, have a single 12 volt feed to my taillight that comes on with the ignition switch. I split that single feed to power two more taillights. Now I have one feed powering three taillights. I want to install a warning light on my dash that will come on automatically, if I lose the 12 volts where the single feed splits, and all three lights go out. I just wish to monitor the taillights only, and only if all three taillights go out. I won't monitor the brake lights or turn signals. I'm sure that relays would come into play here, but I'm not sure which relays or how they would be wired in. any suggestions would be welcome. It's a '78 GL1000, not that it matters much in this case.

Thanks...........................Dave

Maybe this is too simplistic but here goes.

How about one more lead to the warning light that would go out if the connection is lost.

[Solina Dave]

i have a question, and I'm not sure if the answer is so simple that I should feel embarrassed, or not. But here it is anyway.
I of course, have a single 12 volt feed to my taillight that comes on with the ignition switch. I split that single feed to power two more taillights. Now I have one feed powering three taillights. I want to install a warning light on my dash that will come on automatically, if I lose the 12 volts where the single feed splits, and all three lights go out. I just wish to monitor the taillights only, and only if all three taillights go out. I won't monitor the brake lights or turn signals. I'm sure that relays would come into play here, but I'm not sure which relays or how they would be wired in. any suggestions would be welcome. It's a '78 GL1000, not that it matters much in this case.

Thanks...........................Dave

Maybe this is too simplistic but here goes.

How about one more lead to the warning light that would go out if the connection is lost.

You're absolutely right SnoBrdr. That would be much simpler, and if I had any sense that's the way I'd go. Key word "sense". I thought about doing it that way, but I know that I'm much more likely to notice a light coming on, than I am a light going off.
But you're right, it would be a lot simpler. So I guess I'll have to consider doing it your way, and just adapt. After all, I suppose the lights are going "OFF", aren't they?

Thanks for your help! ...................................Dave

[SnoBrdr]

i have a question, and I'm not sure if the answer is so simple that I should feel embarrassed, or not. But here it is anyway.
I of course, have a single 12 volt feed to my taillight that comes on with the ignition switch. I split that single feed to power two more taillights. Now I have one feed powering three taillights. I want to install a warning light on my dash that will come on automatically, if I lose the 12 volts where the single feed splits, and all three lights go out. I just wish to monitor the taillights only, and only if all three taillights go out. I won't monitor the brake lights or turn signals. I'm sure that relays would come into play here, but I'm not sure which relays or how they would be wired in. any suggestions would be welcome. It's a '78 GL1000, not that it matters much in this case.

Thanks...........................Dave

Maybe this is too simplistic but here goes.

How about one more lead to the warning light that would go out if the connection is lost.

You're absolutely right SnoBrdr. That would be much simpler, and if I had any sense that's the way I'd go. Key word "sense". I thought about doing it that way, but I know that I'm much more likely to notice a light coming on, than I am a light going off.
But you're right, it would be a lot simpler. So I guess I'll have to consider doing it your way, and just adapt. After all, I suppose the lights are going "OFF", aren't they?

Thanks for your help! ...................................Dave

Well if you only right at night it would be perfect !

[virgilmobile]

So you would like a light to come on if the rear lights loose power.?
Not so bad...use the indicator lamp as described but do not ground it.Instead,attach the 2 wires from the dash light this way...One lead goes to switched power and the other feeds back to the tail light.
When there working,both ends if the lamp have power...it won't light....tail lamps loose power...now the lamp has power on one wire and the tail lamp filaments as the ground...Enough to light a indicator or bright LED.

[Solina Dave]

So you would like a light to come on if the rear lights loose power.?
Not so bad...use the indicator lamp as described but do not ground it.Instead,attach the 2 wires from the dash light this way...One lead goes to switched power and the other feeds back to the tail light.
When there working,both ends if the lamp have power...it won't light....tail lamps loose power...now the lamp has power on one wire and the tail lamp filaments as the ground...Enough to light a indicator or bright LED.

Is this what you're saying Virgil? Considering the path of least resistance, and all that, and if the main feed from the ignition switch or wherever, was intact, the tail lamp would be "on", but the warning lamp, in parallel with the main feed, would remain "off".
If the main feed, for whatever reason, became "open" somewhere, all power would flow through the warning lamp circuit, and through the tail lamp's filament to ground, and the warning lamp would illuminate. Is that about right?
Also, would I be advised to use a lower wattage LED warning light , or could I still use an incandescent bulb? Or would it matter?

Thank you.....................Dave

[WingAdmin]

I think he meant more like this:

Warning light

When the tail light is intact, its resistance is extremely low. A 27 watt bulb is about 5 ohms in resistance. Put a much higher resistance resistor in series with the LED, which are both in parallel with the bulb. For a typical LED, a 390 ohm current limiting resistor would not be out of the question. 390 is much higher than 5, so the path of least resistance is going to mean virtually no power is going through the LED, and it will remain dark.

When the bulb burns out, the only remaining path for the current is through the LED, and it lights up.

[Solina Dave]

Thanks WingAdmin. That would no doubt work to indicate a blown taillight bulb. I have 3 taillights on a single feed. I'm pretty sure that feed comes straight from the ignition switch. I'm not so much interested in being alerted to a bulb burning out. If one does burn out, I'll still have two lights and I'll replace the burnt bulb during routine maintenance.
What I am interested in, is being alerted to the fact that I have an interruption somewhere in the main feed to all three taillights. If there was an interruption in power to those taillights while I was riding, I wouldn't be aware of it. Hence, the advantage of having the warning light.
Your idea would probably still work in that case, but the connection point for the LED warning light circuit would have to start as close as possible to the contact point in the ignition switch, to ensure power to the LED, in the event of a failure somewhere in the main feed to the taillights.
Thanks again for your help. I'm not too familiar with LEDs, but your combination of an LED and a resistor would no doubt work.

Dave

[WingAdmin]

Thanks WingAdmin. That would no doubt work to indicate a blown taillight bulb. I have 3 taillights on a single feed. I'm pretty sure that feed comes straight from the ignition switch. I'm not so much interested in being alerted to a bulb burning out. If one does burn out, I'll still have two lights and I'll replace the burnt bulb during routine maintenance.
What I am interested in, is being alerted to the fact that I have an interruption somewhere in the main feed to all three taillights. If there was an interruption in power to those taillights while I was riding, I wouldn't be aware of it. Hence, the advantage of having the warning light.
Your idea would probably still work in that case, but the connection point for the LED warning light circuit would have to start as close as possible to the contact point in the ignition switch, to ensure power to the LED, in the event of a failure somewhere in the main feed to the taillights.
Thanks again for your help. I'm not too familiar with LEDs, but your combination of an LED and a resistor would no doubt work.

Dave

In that case I think I would put a small relay in parallel with your taillights, so that the power lighting the taillights also powers the coil of the relay.

I would use the normally closed contacts to power a warning light - so if the power was interrupted and the taillights went out, the relay would open, the normally closed contacts would close, and the warning light would come on.

[Solina Dave]

In that case I think I would put a small relay in parallel with your taillights, so that the power lighting the taillights also powers the coil of the relay.
I would use the normally closed contacts to power a warning light - so if the power was interrupted and the taillights went out, the relay would open, the normally closed contacts would close, and the warning light would come on.

Funny you should say that. A week ago I drew up this possible scenario. It looks more complicated than it is, and probably has an unnecessary switch in the warning light circuit, but I think we're somewhat together on this. I even added a switched, back-up supply, in the unlikely event that it becomes needed. I'm probably worrying too much about nothing, but it gives me something to do. Don't laugh!!

Thanks again...................Dave

[WingAdmin]

You got it, that's exactly what I described!