Hazard signals and turn signal on same wire

I am confused and need some help please.

What I am trying to do is make LED turn signal lights attached to my side view mirrors, WITH hazard signals.

I tap the signal from my car and have right/left blinking +12v wires. DONE! PROJECT FINISHED. Now, I tap the HAZARD SIGNAL which is just ONE WIRE that blinks. If I attach that wire to the leds, then nothing stops the electric from flowing back from left or right signal when THAT is powered on.

How do I isolate left, right signals from the hazard signal - which would trigger both left and right at the same time (without dropping the voltage which would dim the lights)?


The diode inline with a power will drop the voltage. That's what I am trying to avoid.

You might try the diode anyway. The voltage drop will probably be less than the voltage drop you get when you shut-off the engine.

Otherwise you can probably use a relay (or two). I can't tell you how to wire it up, since I don't know how your car is wired. You might need diodes on the relay coils.

...Normally the same lamps are used for the turn signals and 4-way flashers, so you would just have to wire the mirrors in parallel with the signal lamps. And if the brake lights are shared with the turn signal lamps, you'd need to wire-up to the front signals.

Hi, why are you worried about 0.7V drop, your 12V car that actually runs at 13.8V most of the time it is running. 0.7V will not noticeably dim the LEDs when your are using 12V system.

Tom...... :)

PS, you must have the new LEDs connected to the wrong place to have the direction indicators working but the hazard function not working. Your new LEDs should be in parallel with the existing direction indicator lights, that way all the functions of these lights will work without any modification.

Yes bingo I have new led's - I am trying to hook up something I modified myself.

Are you sure its .07 volts? I was reading more like 1.2 volts, on an in4007 which will effect the brightness. Of course I can re/do the current limit resistor - is one way to resolve this. I was just wondering if anyone knew any other tricks, outside of a diode or using a bulky relay, and not spending 1 hour soldering a circuit board.

0.7V, not 0.07V.

Schottky diodes have smaller forward voltages (0.4V or so).

Why aren’t you tapping into the wires to the existing bulbs, which will be
doing the right thing already?

Actually, the wire I used I just tested seems to trigger the left and right lamps when I toggle the hazard anyway - so this really doesn't matter now. But I got stuck a few times in the past where I couldn't figure out how to resolve something like this which is why I was looking for advice.

I prefer to wire my connections closer to the dashboard instead of running 12' of wire back and fourth for every light in the truck that I want to modify.

a schematic would help.

using a FET on each side allows you to chose which is used to complete the circuit.

want both ? you have a switch for the left, a switch for the right and a switch for both.
send the signal to the FET controlling the LED.

the FET will have a lower resistance so your lights will have full power.
this sketch shows an N type, but if you are feeding power, then use a P type.

Okay yes, I can see that now would probably work ideally. Though the shotty diodes sound good too if only going to take up .5 volts. Thanks.