Converting Turn Signals to Running Lights (RunTurn Stay On)

Scott & Heather · May 08, 2012, 07:24:13 PM

I would love to convert my L.E.D. front turn signals into running lights with the turn signal feature active. Meaning they default to staying ON and blink off when signaling, and return to staying ON when not signaling. I've Googled this but have only found some info on motorcyclists doing this. How complicated would the wiring changes be to do this?

Eric · May 08, 2012, 07:46:40 PM

Im not a 100% But I did just that on my trike and I used a relay to cycle the ground instead of the hot.... Had a specific relay too default on not off if I'm correct... Was a 20$ fix from he local parts house...

Have fun !

Eric

Scott & Heather · May 08, 2012, 07:55:03 PM

Thanks Eric. I'll do more research on it. Did you ever get your spin welding done? Oh wait, I'm off topic in my own thread...sheesh. Defaulting the ground via relay versus hot is an interesting way to do it. Why not through the hot?

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fraser8 · May 08, 2012, 08:22:22 PM

You could use a relay constant on, when the signal light power goes to it the relay trips and goes to the flasher circuit that is attached to the same bulb. This is the simple explanation.

thomasinnv · May 08, 2012, 11:46:34 PM

I would think that by switching the ground instead of the + you would have to have the lights on all the time or you would have no signals during daylight if the lights are off.

RJ · May 09, 2012, 12:34:04 AM

Scott -

GM uses the "kiss principle" to get their turn signals/side marker lights to flash on their cars/trucks, especially on models with side markers somewhere other than in the headlight cluster. It's been awhile since I've seen the schematic, but basically the side marker grounds thru the turn signal filament.

IIRC, when the headlights are on, including the parking lamps and side markers, the flashing alternates between the turn signal and the side marker light. OTOH, when the headlights are off, the turn signal and side marker flash together. Or maybe it's the opposite, I'm too tired right now to remember. . .

Works beautifully up front, and it's quite simple. BUT: It does not work for the rear if the tail/brake light share the same bulb, because when you step on the brakes, the side markers go out - not good!

I'm not sure how this would work with LED lights, but there must be a way. . .

FWIW & HTH. . .

Oonrahnjay · May 09, 2012, 01:22:43 AM

Quote from: thomasinnv on May 08, 2012, 11:46:34 PMI would think that by switching the ground instead of the + you would have to have the lights on all the time or you would have no signals during daylight if the lights are off.

No, not necessarily. It's not always advantageous to switch by ground but sometimes it is. Esp. if you're using a multi-function item (like a lighting device), if you're feeding it power from more than one circuit, you're likely to have feedback power applied to the unused circuits (unless you go to the complication of diodes, etc.). If you're switching by ground, you have only one hot but if the device is switched on through a ground, the other ground circuits are just there, assuming that they are not switched to ground, and they're isolated from each other. You also have the option of one control state (such as a flasher) on one ground control and steady state on the other; it may be necessary to "bridge" relays (such as the ganged relays in a 3-2 converter box for a trailer) but you can have a lot of control and choice of operating states with very simple circuits.

Scott & Heather · May 09, 2012, 03:58:07 AM

I'm not planning on tying in the headlamp/turn signals because of the obvious issues with 12/24 volt mixups. So I think a relay with a closing ground might actually be perfect...GM is exactly who I had in mind...the new cadillacs all have this feature...as does some buicks, and others.