Pardon my lack of technical terms here; essentially I have an under glow kit on my car (along with some other lighting) that I want to expand the circuit on. I bought a pair of 5 pin relays to accomplish my task. Essentially the running board lights will constantly be on, until I use my turn signals in which case the appropriate running board light will blink like my turn signal.

The lights have four wires, a positive, and three negatives that create the colors.

This is the relay I bought:


Here is the diagram for the normally off circuit they have:

Normally off circuit

Here is the wiring harness:

Wiring harness

And here is the diagram I came up with to accomplish my task. As I stated before, I’m not great with technical terms so please pardon that.


simulate this circuit – Schematic created using CircuitLab

Now, for testing I’ve scaled this down to just the relay and a single light; for some reason, I can’t seem to get the light to come on even with the turn signal on. When I attach the light straight to the battery, it comes on.

I feel like I’m just doing something wrong and can’t figure it out.

For clarity, the goal is to have the light on when the turn signal is off, and blink when the turn signal is on.

Also, if the above isn’t possible, even the normally off diagram didn’t work; how can I correct to achieve it?

  • \$\begingroup\$ @Passerby So the lights have a positive and negative that I’ve already located and hooked into properly for a sequential signal on the back of my car. It’s a 2016 Mitsubishi Lancer Evolution. \$\endgroup\$
    – Taco
    Commented Oct 20, 2018 at 4:24
  • \$\begingroup\$ @Passerby That is correct; I’ll be wiring the main portions of the circuit today; I can go back later to add the relays. I would love to see your answer! \$\endgroup\$
    – Taco
    Commented Oct 20, 2018 at 17:57
  • \$\begingroup\$ Made a schematic with what I explained, but no, that won't work as I thought. The lights would still alternate. With regular switches or relays, it would be easier to tap into it, as you could use the control switch as well. Hmm, I'll keep thinking. That, or use timer relays or micro controllers. \$\endgroup\$
    – Passerby
    Commented Oct 20, 2018 at 18:45
  • \$\begingroup\$ @Passerby Will what I have blink when the switch is off, and stay on when the switch is on? I appreciate the help, and at least a basic setup will hold me off to buy addition components later if needed. My budget is roughly $50 for the next purchase so if you’ve got a way to accomplish the full goal with what I have plus less than $50 worth of extra components, then feel free to post it! :) \$\endgroup\$
    – Taco
    Commented Oct 20, 2018 at 18:51
  • \$\begingroup\$ You have it wired so the running board is off when the turn signal is off. They blink together, but the running board is off most of the time. If you connect the running board positive to 87a instead, the running board is on when the turn signal is off. So they will blink in alternate manner, with the running board on most of the time. The other connections, 30, 86 and 85 are good. \$\endgroup\$
    – Passerby
    Commented Oct 20, 2018 at 18:56

1 Answer 1


This is a simple schematic, for alternative blinking. Turn bulb on, your led module off. Once the turn signal stops blinking, the running board would stay on, as long as your Switch is on. Side note, I hope you added a fuse to your wiring between the battery and switch. Safety first.


simulate this circuit – Schematic created using CircuitLab

The turn signal power must come from before the turn bulb, somewhere from the red circle, or a similar connection. (Wiring diagram for some unknown year of Mitsubishi Lancer, see page 9-70) Just tap/slice into it.

enter image description here

  • \$\begingroup\$ I’m not fully educated in reading the first schematic; can you explain 87a and 85 both connecting to the led? \$\endgroup\$
    – Taco
    Commented Oct 20, 2018 at 19:30
  • \$\begingroup\$ Okay, so connecting 85 to ground and negative to the negative on the battery got it to work; I’m assuming the relay is supposed to click audibly? \$\endgroup\$
    – Taco
    Commented Oct 20, 2018 at 19:35
  • \$\begingroup\$ Yes. 85 is the negative side of the relay coil, so it should, in this use, connect to ground just like the led module negative connects to ground/battery negative. 87A is the "Normally connected/closed" side of the relay's switch. When the relay is off, it physically connects 30 to 87A, providing a route for power to your led module positive. And yes, the relay will audibly click. That's normal for mechanical relays. \$\endgroup\$
    – Passerby
    Commented Oct 20, 2018 at 19:37
  • \$\begingroup\$ one last question on this; if my switch is in the off position the led shouldn’t blink correct? \$\endgroup\$
    – Taco
    Commented Oct 20, 2018 at 21:21
  • \$\begingroup\$ If your switch is in the off position, it shouldn't be on at all. That's the switch in your diagram. If you want a switch to just turn on and off the blink feature, add it either before 86 or after 85. \$\endgroup\$
    – Passerby
    Commented Oct 20, 2018 at 23:00

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