I'm in the process of adding another brake light to my truck. I bought the kit to add a trailer harness and planned on hooking the light up through that. However, upon actually doing 30 seconds of research I found out that a 4-wire trailer harness provides wires for the left bake/turn signal, the right brake/turn signal, running lights, and a ground. This won't really work for my application since the added brake light will also flash when that side's blinker is on.
Is there any way I can make the added light stay on solid even when the blinkers are on? What if I ran both the left and the right side wires to a relay and then connected the light? (Please forgive me if this isn't the right use of a relay... I have close to no experience with them. )
I've got a brake light plug for my receiver hitch. didn't do anything fancy to it. typical 4 wire trailer harness, just connected right out of box and it lights with brake only. does not flash with turn signals.
I looked around for information on those hitch covers but couldn't find any good details. I'm guessing there's some sort of system built in so that it doesn't blink. ...now if I could just figure out what that system is.
Hmm... I find that interesting. traditionally, the white is the ground and the green would be for the right turn/brake light. So theoretically it should come on with your brake lights and flash with the right blinker, but obviously it doesn't. I'm going to have to do some more digging. There has to be info out there somewhere!
My cousin has the same type of cover on her 4 runner and it only lights up when the brake pedal is depressed....If you dont m,ind me asking .. what effect are you trying to get out of this light cover... or are you simply inquiring on how it works ?
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the more I think about this... the flashing turn signal is a function of the bulb, isn't it? the power in the green wire is activated with either the brake OR the turn signal is selected. if the bulb at the other end is not a dual function brake/turn signal, the turn signal does nothing. the brake bulb on the other hand is activated by either/both the green and/or the yellow (left/right) wires.
2bunik, I'm not using a hitch cover. I'm trying to add a brake light through a 4-wire trailer harness. We're just using it as an example to see how it works.
barch97 wrote:the more I think about this... the flashing turn signal is a function of the bulb, isn't it? the power in the green wire is activated with either the brake OR the turn signal is selected. if the bulb at the other end is not a dual function brake/turn signal, the turn signal does nothing. the brake bulb on the other hand is activated by either/both the green and/or the yellow (left/right) wires.
Here's how I think it works. The tail lights and all other running lights are powered by the brown wire. If you step on the brake power is sent through both the yellow and the green wires. If you step on the brake and turn on your left turn signal, constant power is sent through the green wire and a signal is sent through the yellow wire, then shut off, then back on, then shut off, etc. (Caused by your flasher)
This is my theory on how it works. However I could be wrong. Maybe a standard bulb has three filaments, each only turning on with a certain amount of current. Who knows.
I'll play around with it some more this afternoon and see what I can find.
no because there are relays under your dash, you can hear them clicking on and on under the dash when the blinkers (redneck word) are on, plus if you have ever had that relay go bad your turn signals would either not come on at all or would stay lit, depending on side the relay was stuck on, this is confusing me about how it works, i feel like the answer is right in front of me and i just need to slow down and actually think about it, we will see what i can come up with
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The only other idea I had was to put a diode on the green and yellow wires and hook them directly to my added brake light.
This would cause the light to be powered whenever a signal was received from either wire, and no current to travel "back" through the system.
-Eric H
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After doing some more digging around I got the results I was looking for. However it wasn't done by using the trailer harness. There is a blue wire on the rear driver's side by the bumper bracket labeled "HI BRAKE" (or something like that; the lettering was quite weathered). I believe the intended purpose of the wire is for toppers with a brake light up in the rear window. I just hooked my light up to this wire and ran a ground to the frame. Works great!
Although, I'm still stumped on how to make it work through the trailer harness. Not that I need to know anymore... but I feel kind of defeated.
-Eric H
[size=75][b]2001 Chevy S-10 LS Ext Cab 4x4[/b] -2" BL; US Wheel Stars; 30x9.5 Dunlop Mud Rovers; home made topper; RF 800a2; Two RF He2 12"
[b][url=http://photos.yahoo.com/negativez0]1995 White Camaro Convertible 3.4 A4[/url] -[i]TRADED IN![/i][/b] -RK-Sport Big Block Hood & Sport Wing; Black & Blue Pearl Racing Stripes; 17x9½" König Monsoons; Flowmaster w/ Quad 2½" Tips [/size]
Eric H wrote:...There is a blue wire on the rear driver's side by the bumper bracket labeled "HI BRAKE" (or something like that; the lettering was quite weathered). I believe the intended purpose of the wire is for toppers with a brake light up in the rear window. I just hooked my light up to this wire and ran a ground to the frame. Works great!
Thank YOU very much!
I thought that wire might have been for the trailer brake controller which color codes the brake wire blue. With my tunnel vision I did not think of that being a high mount brake light connection.
That does explain quite a bit and eliminates my search for the other end of that wire.
EDIT: Looks like in the other thread Dragonmaster pointed to it being a brake light wire, but you connected and tested it, which makes a believer out of me (I can be a bit sceptical )
Last edited by HenryJ on Fri Nov 19, 2004 4:03 pm, edited 2 times in total.
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[size=75][b]2001 Chevy S-10 LS Ext Cab 4x4[/b] -2" BL; US Wheel Stars; 30x9.5 Dunlop Mud Rovers; home made topper; RF 800a2; Two RF He2 12"
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Not sure I understand the question. Are you asking how the wire I tapped into can tell the difference between power from the brakes or power from the turn signals?
If so, I'm guessing the other end of the wire is under the dash right above the brake pedal and connected into the brake switch. When I had my Camaro I upgraded the tail lights and needed a wire to do the same thing and it was located there.
-Eric H
[size=75][b]2001 Chevy S-10 LS Ext Cab 4x4[/b] -2" BL; US Wheel Stars; 30x9.5 Dunlop Mud Rovers; home made topper; RF 800a2; Two RF He2 12"
[b][url=http://photos.yahoo.com/negativez0]1995 White Camaro Convertible 3.4 A4[/url] -[i]TRADED IN![/i][/b] -RK-Sport Big Block Hood & Sport Wing; Black & Blue Pearl Racing Stripes; 17x9½" König Monsoons; Flowmaster w/ Quad 2½" Tips [/size]
I found out that a 4-wire trailer harness provides wires for the left bake/turn signal, the right brake/turn signal, running lights, and a ground. This won't really work for my application since the added brake light will also flash when that side's blinker is on.
)
I'm going to have to do some more digging. There has to be info out there somewhere!
)
