electrical expert

[photobug]

In need of someone that has a bit more electrical knowledge than I do. I'm trying to attach an extra brake light to my bike rack that hooks up to the trailer hitch using the trailer hitch wiring. Thought I had it figured out until I tried it. Went to try the turn signals and both sides on the coach blinked. disconnected hitch wires and turn signals went back to normal. My thought are since both sides are connected in the light on the bike rack, it's running power back through the side that isn't being used. What I probably need is a couple of diodes to prevent reverse flow on both turn signal lights. Here's where I need the help. How do I determine what kind/size/rating diode to use? I know the theory, just never had to use any in a project that wasn't already pre set up for me.

[DrewE]

Your basic problem is that there isn't a brake light line on the trailer connector; there's just a left brake/turn and a right brake/turn. It sounds as though you just shorted the two together and fed that to your new brake light, and apparently the same circuits power the vehicle's turn signal lights. Even with steering diodes to prevent back-feeding, you'll still have the problem of the brake light on the bike rack blinking whenever a turn signal is on and the brakes are not on, say when changing lanes or merging onto the highway, which I suspect could be rather confusing to drivers behind you.

If you have a third brake light on your vehicle (or no third brake light but separate signal and brake circuits at each side), probably the simplest approach would be to tap into that line and run a separate connector for the light on your bike rack, not plugging into the trailer connector at all. If you don't have a separate independent brake light circuit anywhere at the back of the vehicle, it will be pretty hard to do what you would like to do; you'd probably have to run a wire to the front and tie into the wiring harness somewhere in the dash area, perhaps at the brake pedal switch, and the details on how that would work probably vary somewhat from vehicle to vehicle.

[LittleBill]

shouldn't need an adapter. simply tie into only 1 turn signal light.

[Bobbo]

The EASIEST solution is to pick either the right brake light/turn signal or the left brake light/turn signal and hook to that. It will function perfectly fine as a brake light, but will flash with that turn signal. By tapping into both the right and the left signals, you don't get increased functionality as a brake light, but you get flashing on both turn signals AND backfeeding, as you have found.

The harder solution is to find the wire feeding your third brake light and tap in to that.

photobug wrote:
Got one controlling the 3rd brake light on the coach. it's too big to fit on the bike rack, and don't want to mess up the hitch wiring if I need to tow something.

After posting, I saw you posted this just before me. This gives you the perfect answer.



Tap into the "STOP" wire and "GROUND" wire and run them to the light bar with a 2 pin connector rather than the trailer hitch connector.

[photobug]

Got one controlling the 3rd brake light on the coach. it's too big to fit on the bike rack, and don't want to mess up the hitch wiring if I need to tow something.

[azrving]

Maybe you can use one of those adapters that are used on vehicles with separate brake and signal bulbs.
Someone else may explain it better since it's been a long time since I dealt with it


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