Trailer wiring question

So, I just picked up a cheap hitch cover with LED brake light built in that plugs into the trailer wiring connector. Problem is, it only taps the green lead, so the light behaves exactly like the right brake/turn light and blinks when I'm signaling right.

My goals are as follows:

1) Have the hitch light be on when the brakes are on. 2) Have the hitch light NOT blink when either turn signal is on. 3) Not damage my Jeep's electrical system in any way.

The question is this: Can I use an isolating diode (like the Roadmaster Hy-Power) to connect both the left (yellow) and right (green) feeds together and use that as an input for the LED array?

My thinking is that when the brakes are on, I've got #1 covered, since both inputs to the diode are giving a solid 12v. When one turn signal or the other is on, the light will still be getting a solid 12v from whichever light isn't blinking, taking care of #2. I'm still good on #3 as well, since the diode would protect the left and right circuits from interfering with each other.

I think I've got this right and was just going to start experimenting, but first I wanted someone with more electronics experience to check my thinking so I wouldn't accidentally miss goal #3. :)

Reply to
Garth Almgren
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why don't you just figure out which wire has power only when the tail lights are on and you'd be good to go? OR am I missing something?

Garth Almgren wrote:

Reply to
RSMuddog via CarKB.com

What you're missing is standard 4-flat trailer wiring: One wire for ground, one wire for running lights, one wire for left brake/turn, and one for right brake/turn. :)

Besides, since the Jeep has a combination brake/turn signal in the rear (one dual-filament bulb does triple duty as running lights, brake lights, and turn signals) and is one year early for a CHMSL (center high-mounted stop light), there is no single wire that does only brakes.

Reply to
Garth Almgren

The problem here is that, unless the brakes are applied, the LED assy is still going to get left or right turn signal power, and the LED is going to blink. As long as you always apply the brakes before you activate the turn signals, what you propose will work. Of course that is not normal operation. Right off hand I don't know how you would make it work like you want. I'll sleep on it. :-)

Dick

Reply to
Dick

Reply to
L.W. (Bill) Hughes III

Do you have a "third brake light" you can tap into?

Spdloader

Reply to
Spdloader

You can't do what you want with diodes. Someone designed that unit and some silly 3rd brake light units for trailers without knowing how the power actually works. These units are useless because there is no way to distinguish power from the brake pedal switch or from the signal switch. Power is power.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's - G> So, I just picked up a cheap hitch cover with LED brake light built in
Reply to
Mike Romain

Well I wish someone would throw one my way. I wanna put it back*on* my Jeep. The previous owner thought it looked better without it, I guess.

-- Old Crow "Yol Bolsun!" '82 FLTC-P "Miss Pearl" '95 YJ Rio Grande BS#133, SENS, TOMKAT, MAMBM

Reply to
Old Crow

Sounds like you've never been to Tijuana. God Bless America, Bill O|||||||O mailto: snipped-for-privacy@aol.com

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Reply to
L.W. (Bill) Hughes III

Very good point, and as someone else pointed out, my method would still have it blinking when I'm signalling but not on the brakes.

On the upside, there seem to be a couple 3rd brake logic circuits that'll work much better than my diode idea for sale at JC Whitney. Example:

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-- ~Garth (via Google)

Reply to
Garth Almgren

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That is an interesting unit and would do the trick.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's - Gone to the rust pile... Canadian Off Road Trips Photos: Non members can still view! Jan/06
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(More Off Road album links at bottom of the view page)
Reply to
Mike Romain

Unlike Bill, who goes there regularly for Donkey Dick Cumshakes. Down the hatch, fatfag!

Reply to
L.W. Bill Gay Cocksucker Hughes

Well, yes I have. It's been a few years, though. I just want the third brake light back on my Jeep. Then again, I'm looking for a cheap Hypercharger for my Harley and can't find one of them, either(which surprises me as much as people bash*them* too).

-- Old Crow "Yol Bolsun!" '82 FLTC-P "Miss Pearl" '95 YJ Rio Grande BS#133, SENS, TOMKAT, MAMBM

Reply to
Old Crow

without knowing how many wires are on the device, its hard to say. make a custom plug, take your trailer wire on your vehicle, isolate the brake light wire and run that and a ground to the device you are using. the tailights have 2 light bulbs. one for blinker and one for brake. find that wire, from each side or one and use it. and a ground.

Garth Almgren wrote:

Reply to
RSMuddog via CarKB.com

'My' Jeep, which is like his 'Wrangler' only has 'one' bulb and 'one' filament for brakes and signals which requires a logic circuit to separate/consolidate the signals.

You seem to be 'full' of good advice (not).

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail > without knowing how many wires are on the device, its hard to say. make a
Reply to
Mike Romain

"Problem is, it only taps the green lead," My apologies if that wasn't clear, but I thought it was.

There is no brake light wire.

Have you ever seen a Wrangler or CJ before? There's only one bulb on each side for the stop, turn, and running light functions.

Nope, there's one wire for the brake/turn signal, and one wire for the running lights.

Doesn't exist. Hence my need for some kind of logic circuit, and my amateur attempt to design one myself.

You think? :)

Anyway, I went and ordered the JC Whitney logic circuit, which should do the trick.

Reply to
Garth Almgren

Nope, my Wrangler is a '93, and like all light trucks in the US, the CHMSL wasn't implemented in Wranglers until '94.

Reply to
Garth Almgren

While European automotive lighting standards are for the most part miles ahead of our FMVSS, the CHMSL is one American invention that really was and is a good idea.

Reply to
Garth Almgren

Your ass seems to be full of Bill Hughes' chunky cockspooge.

Reply to
Mike Romaine

Reply to
L.W. (Bill) Hughes III

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