Garth Almgren

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. :)


--
~/Garth - 1993 Wrangler S 2.5
{ }|||||||{ } "MukYJ"

RSMuddog via CarKB.com

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:
>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. :)
>

--
Message posted via CarKB.com
http://www.carkb.com/Uwe/Forums.aspx/jeep-cars/200707/1

RSMuddog via CarKB.com

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:
>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. :)
>

--
Message posted via CarKB.com
http://www.carkb.com/Uwe/Forums.aspx/jeep-cars/200707/1

RSMuddog via CarKB.com

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:
>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. :)
>

--
Message posted via CarKB.com
http://www.carkb.com/Uwe/Forums.aspx/jeep-cars/200707/1

RSMuddog via CarKB.com

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:
>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. :)
>

--
Message posted via CarKB.com
http://www.carkb.com/Uwe/Forums.aspx/jeep-cars/200707/1

Garth Almgren

Around 7/16/2007 8:54 PM, RSMuddog via CarKB.com wrote:

> 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?


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.


--
~/Garth - 1993 Wrangler S 2.5
{ }|||||||{ } "MukYJ"

Garth Almgren

Around 7/16/2007 8:54 PM, RSMuddog via CarKB.com wrote:

> 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?


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.


--
~/Garth - 1993 Wrangler S 2.5
{ }|||||||{ } "MukYJ"

Garth Almgren

Around 7/16/2007 8:54 PM, RSMuddog via CarKB.com wrote:

> 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?


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.


--
~/Garth - 1993 Wrangler S 2.5
{ }|||||||{ } "MukYJ"

Garth Almgren

Around 7/16/2007 8:54 PM, RSMuddog via CarKB.com wrote:

> 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?


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.


--
~/Garth - 1993 Wrangler S 2.5
{ }|||||||{ } "MukYJ"

Dick

On Mon, 16 Jul 2007 21:12:05 -0700, Garth Almgren <nospam@mukyj.com>
wrote:

>Around 7/16/2007 8:54 PM, RSMuddog via CarKB.com wrote:
>
>> 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?
>
>
>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.

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. :-)

----

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