3rd brakelight!!

[brian_bp]

On my new jeep Cherokee the turn lights are amber, and the brake lights are red.. So.. different wires.

But... the harness plug is a four prong...????Shouldn't it be a five prong? G>LT>RT>B>TL??

Right... but the Jeep probably has a converter installed which provides combined stop/turn signals for the trailer, despite the separate stop and turn signals on the Jeep. That's the setup in my Toyota van.

[MacGyver]

Micro469 wrote:
On my new jeep Cherokee the turn lights are amber, and the brake lights are red. So. Different wires. But... the harness plug is a four prong.Shouldn't it be a five prong?

I recently installed a wiring harness on a 2007 Jeep Compass, it also has the separate amber turn signals and brake light. I order the custom wire harness from; http://www.autoaccessconnect.com/jeep1.html. They also list the one for the 2007 Cherokee. It consisted of a harness with t-plugs that go to both sides and plug in between the existing light sockets and the OEM harness. There is a logic box that is attached to the inside the left rear fender, which converts the lights to work with a four-wire trailer system. The TTT also has a third LED brake light installed as well. To get around the need for an additional wire to activate it, a logic box was used in conjunction with it. The box appears to activate the third light only when steady current is sensed on at least one side when the brakes are applied.

[bobhenry]

DUH !!!

Good point I guess I need to re-think my side turn indicators !

Thanks guys and gals !

[bobhenry]

With regard to our normal 4 wire system. I am asking the bosch relay guru's this question. If I took a $3.00 bosch relay and enerqized terminal 30 with 1 brake light and 85 with the other would 87 provide 12 volts ? If either 30 or 85 has no current would 87 have no voltage ? If this is correct both brake filiments would have to have current to light the 3rd brake light and a single blinking turnsignal would not provide the voltage needed to illuminate the 3rd light.

[Dale M.]

With regard to our normal 4 wire system. I am asking the bosch relay guru's this question. If I took a $3.00 bosch relay and enerqized terminal 30 with 1 brake light and 85 with the other would 87 provide 12 volts ?

Yes... Providing you have a ground on 86.

If either 30 or 85 has no current would 87 have no voltage ?

Yes.

If this is correct both brake filiments would have to have current to light the 3rd brake light and a single blinking turnsignal would not provide the voltage needed to illuminate the 3rd light.

BUT you will have current on 30 and 85 when ever a turn signal flashes and you have brake applied the flashing turn signal will flash what ever is wired to 87 to flash... Because you are either going to operate/release relay with flasher circuit... OR you will operate relay with brake circuit on 85 but the voltage applied applied to 30 will be flashing...

The problem is you will not have two brake light signals AND a flasher ... You are going to have.

A) two brake light signals (no turn) and yes you get 3rd brake lamp not blinking.

B) Right brake light and left turn. This causes 3rd brake lamp to blink.

C) Left brake light and right turn. This causes 3rd brake lamp to blink.

Terminals 85 and 86 are operate path... You must put a ground on one terminal. The "other" terminal needs 12volts to operate coil. This will be your control, and could be voltage from brake light switch or toggle switch or some other "control".

What ever voltage or ground you apply to 30 will appear on 87a when relay is not operated. When relay IS operated whatever you are applying to 30 will be removed from 87a and applied to 87.

Flip side is if there is 12 volts on 87A and relay is not operated the 12 volts will appear on 30. If you have a ground on 87 and you operate relay (control & ground on 85 & 86) the voltage on 30 will turn off and the ground will appear on terminal 30....

All the relay is a HIGH current version of a "single pole double throw" toggle switch (spdt) that is electrically operated instead of manual (lever) operated....



Dale