kill taillight when reverse light is on
Printed From: the12volt.com
Forum Name: Lights, Neon, LEDs, HIDs
Forum Discription: Under Car Lighting, Strobe Lights, Fog Lights, Headlights, HIDs, DRL, Tail Lights, Brake Lights, Dashboard Lights, WigWag, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=105634
Printed Date: May 15, 2024 at 4:31 PM
Topic: kill taillight when reverse light is on
Posted By: metal_mulisha
Subject: kill taillight when reverse light is on
Date Posted: June 23, 2008 at 11:31 AM
Hey hows it goin all.... Im putting a set of custom 59 Cadillac LED Taillights in my truck. They have the typical 3 wires coming out of the back per lightsper each light. Ground, and the 2 12V connections for running lights & when brakes are applies.. Im runng 2 lights on each side. On top of that, Im running a pair of White HALO's im putting inside the light to use as Reverse Lights. 1 Per side. Does anyone know how I can hook up a couple relays, so basically, when I put the truck into Reverse, the lights that have the halos in them, lose all power & only the halos shine thru? Even when the brake light or turn signals are apprlied? And when I come out of reverse, all power is fully restored. Thanks?
Replies:
Posted By: metal_mulisha
Date Posted: June 23, 2008 at 11:34 AM
Thats what they look like if anyones curious.
Posted By: i am an idiot
Date Posted: June 23, 2008 at 5:32 PM
That will be simple, but I have a question for you. Do the lights pull double duty, meaning is it a blinker and a taillight? If it is just a taillight we can do it with only one relay. If they are blinkers you will have to use one relay per side. 
Posted By: metal_mulisha
Date Posted: June 24, 2008 at 6:58 PM
Yes the lights will act as both a turn signal / brake light & running light. So from the image, ur basically using the ground wire on the lamps am I correct. Thanks for the info on how to do this.
Posted By: i am an idiot
Date Posted: June 24, 2008 at 9:39 PM
The only ground wire that you will be dealing with will be the right most connection on the relay. This is the ground wire for the coil of the relay. The wire on the left of the relay is a positive wire that comes from the reverse light wire. This is the wire that trips the relay to break the connection of the taillight wire. The wire coming out of the bottom of the lamp (in the picture) is the ground of the lamp. The wire that goes out of the top of the relay is the tail/brake/blinker wire. https://www.the12volt.com/relays/relays.asp
Posted By: metal_mulisha
Date Posted: June 24, 2008 at 11:21 PM
Okay, I havnt checked yet, but what if theres 2 wires for the blinker tail etc... And you said 1 relay per side, correct?
Posted By: i am an idiot
Date Posted: June 25, 2008 at 5:47 PM
Do you use your blinkers when backing up? Most people don't even use them while driving and turning or lane changing. Yes you will have to use one relay per side.
Posted By: metal_mulisha
Date Posted: June 28, 2008 at 10:46 PM
lol, no dont think I ever have. But I think the brake lights are on the same circuit as the the signal ligt? Im not 100% sure tho yet. I will try the 1 Relay set up tho, I hope it all works out, once again I appeciate the help.
Posted By: metal_mulisha
Date Posted: August 13, 2008 at 5:11 PM
Okay so heres how it actually works... The Halo Lights have a small inverter box. With just power & ground & the 2 Halo lights plug into the inverter box. Then the taillights have 3 wires.. Ground and 2 Positives, 1 is the parking lamp, the other is signal & brake.. How do I use the relays in this case, do I only use 1 relay for both sides, or 1 on each side.. If the wiring is different now can you please show me how? I guess, I really need the 1 relay to activate the inverter for the halos, and maybe one on the other side just to shut the lights off when put in reverse, if you can let me know, thanks....
Posted By: i am an idiot
Date Posted: August 13, 2008 at 6:57 PM
If nobody helps you in the next few hours, I will look at it when I get back in. Later tonight or in the morning.
Posted By: i am an idiot
Date Posted: August 13, 2008 at 8:20 PM
You will have to use at least 3 relays to do this. You can use a single relay on the parking lights. You will need one relay for the left blinker and brake wire. And another relay for the right side. Here is the diagram for the tail lights. The reverse wire will need to be connected to all three relays and of course the 2 halo lights. Basically the way the relay works is as follows. At rest, terminal 30 is connected to 87A, the center terminal. When the relay is energized, 30 is going to be connected to terminal 87. When energized there is nothing connected to 87A. That will kill your lights when the relay is energized via the reverse wire.
Posted By: metal_mulisha
Date Posted: August 15, 2008 at 11:33 PM
Thanks again for the Help Buddy. I think you forgot to attach the image tho, I dont see anything on here. I appreciate the help, hope I can get it to work.
Posted By: i am an idiot
Date Posted: August 16, 2008 at 7:54 PM
There was a problem with this thread the other night. I had no picture upload button. Our wonderful Administrator repaired it for us. Now I am able to upload the pic for you. You will have to use 3 relays to pull this off. Following is the relay for the taillights. Notice both the left and the right lamps are connected to the relay. You will have to use one relay per side for the brake/blinker lights. The first diagram I posted will only have to be slightly modified to accommodate your need. It says light wire from vehicle taillight wire. What it needs to say is brake/blinker wire from vehicle. You will have to connect the reverse light wire to each of the 3 relays. 
Posted By: metal_mulisha
Date Posted: August 16, 2008 at 11:33 PM
Awesome, once again, I appreciate the help. And Thanks to the Administrator to of course.... Okay, prob a stupid question, but in this image you show the 2 parking lamps, but them theres grounds attached to them. Thats just showing the parking lamps ground wire right? Im not hooking the Ground for the parking lamps up to the relay? Thanks again....
Posted By: i am an idiot
Date Posted: August 17, 2008 at 12:02 AM
On the above picture there are 3 grounds shown. The rightmost terminal of the relay needs to be grounded, and both bulbs need to be grounded.
Posted By: metal_mulisha
Date Posted: September 07, 2008 at 1:58 AM
Welll, I tried the configuration out that you showed me, and it didnt work unfortantely... What its doing, is the taillights dont work at all, turn signals brakes nothing, but as soon as I go into Reverse, then the lights start to work.. I need it to do the opposite tho... Need the lights to function normally seeing as they are taillights... But When Reverse is selected, the lights go out, thus only the reverse light shines... Got any more Ideas i am an idiot... Appreciate all youve done so far to tho... Thanks
Posted By: i am an idiot
Date Posted: September 07, 2008 at 5:41 PM
Can you take a photo of what you have wired up and mail it to me?
Posted By: metal_mulisha
Date Posted: September 21, 2008 at 4:14 PM
Well finally got the lights workin. The store I buaght the relays from had them listed as a 5pin relay, but it was really a SPST 4 pin relay, but had 2 87 Contacts... So I picked up a set of SPDT Relays, and its working flawlessly.. Thanks again i am an idiot.
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