blinker/tail lights question

[rhltechie]

I had a question about running lights, tail lights and such. I don’t have my hitch or the wiring yet but etrailer says I need this one.

What my question is..I had planned on having just two lights on the back that did braking and also did the blinking. Can I also have the running lights on each respective side blink with the back ones? How would this wiring go? Would I need something more than what etrailer says I need?

Thanks,

mandy

[brian_bp]

I assume that your Jeep has separate stop and turn lights, which is why the adapter/converter is needed (and why there are five wires into the converter, and four out).

The side markers can't be hooked up directly to the combined stop/turn on the same side, because then they would go on with brake application. Actually, some people have done this, but that doesn't make it right.

The four-wire output of the converter doesn't have a turn-only signal in it, which leaves two choices that I can think of: more connections between tug and trailer, for some interesting circuit logic.

The problem with more connections (aside from actually doing the wiring) is that you need too many pins on the connector. Instead of the three lighting signals (left, right, tail) of the 4-pin connection, or the four lighting connections of a separate system (left, right, stop, tail), you actually need five: left turn, left stop/turn, right turn, right stop/turn, and tail. Even if you use the common 7-pin connector and use the auxilliary pin for one function, you're still one short. The easiest method would probably be to run an extra four-pin connector (with one unused pin).

Rebuilding the separated turn signals with circuitry on the trailer isn't easy, either. You could use a readily available logic circuit to make a stop-only signal out of the two stop/turns (they're made to run high-level centre-mounted stop lamps), then use it and the stop/turn signal in a relay configuration to run the side markers.

Either scheme seems like a hassle to me. I would rather just do the whole trailer with separate stop and turn lamps, including the main lamps on the back. Then a simple isolator would be used instead of the converter in the T-One setup (you still need the wiring harness to intercept the Jeep's wiring), and some connector with enough pins (I would use a 7-pin) to get all five wires (ground, left, right, stop, tail) to the trailer.

With any scheme for blinking marker lights, the lamps need either two levels of brightness (two bulbs or a double-filament bulb), or to be driven by something like a relay which interrupts the marker (tail) power to cause the flashing. The dual-intensity system gives a much clearer signal to other drivers, which I assume is the whole point.

[rhltechie]

yikes..yeah that sounds more complicated that i wish to get for a few blinking lights!! my original plan was actually just to do what i believe you described. have a brake and a turn signal light seperate on the back for each side. so you say i will need some sort of "isolator" to make this work?

[BPFox]

yikes..yeah that sounds more complicated that i wish to get for a few blinking lights!! my original plan was actually just to do what i believe you described. have a brake and a turn signal light seperate on the back for each side. so you say i will need some sort of "isolator" to make this work?

If you want to have separate turn signals in the back that's not a big problem. Don't buy the adapter and use a connector that has at least 5 pins. On my GMC van the wiring is as follows. White = Negative or Ground, Yellow = Left Turn, Green = Right Turn, Red = Brake Lights and Brown = Running/Parking Lights. On the back of your trailer you can use pretty much whatever you want for lights. You might consider amber lights for your turn signals, but you could use red as well. Regardless the wiring is pretty simple and not adapters or converters are needed. Just one more wire and a couple of lights.

[rhltechie]

hi..thanks for reply.

Don't buy the adapter and use a connector that has at least 5 pins.

I dont think I understand this...I need something that connects at the back of the jeep to go out to the trailer correct? I thought this was the adapter portion...hmm....i am a little confuzzled

[Steve F]

I missed this somewhere, what sort of Jeep is it? My XJ Cherokee had all the wires needed behind the passenger side (drivers side over there) panel in the cargo area including both turn signals etc. I connected up to those and ran the wiring out the grommet already there straight to a 7 pin plug.

Some vehicles have a plug in the wiring harness at the rear that you can unplug and plug in an adapter (plug the original plug back into this) with all the wiring done which then runs out to the back of the vehicle and on the end you have 5 pin connector mentioned which the trailer plugs into.

Hmmm I dont think I explained that very well

Cheers
Steve

[rhltechie]

hmmm..yeah, i am still a lil confused...

I have a 2000 jeep cherokee, apparently i have to pry off the panel in the cargo area to get to the wiring for the hitch. i havent dont so to take a look yet...but it was just my understanding i needed some sort of adapter for my lights. There cant be just pig tails hangin out back there right? lol

[Steve F]

Mines a 2000 as well, no there aren't any pigtails but all the wires are there running to thier respective lights and it is easy to splice into them, like I say both side turn signals have a wire there along with everything else you need. The adapter can be bought and plugged straight in here think of it as a 'T' where the original wiring plugs into the top of the 'T' and comes out the other side of the top of the 'T' and the pigtail the adapter provides is the lower part of the 'T'. I didn't bother with the adapter and just spliced into the existing wiring creating my own pigtail.

Cheers
Steve

[rhltechie]

ah..i gotcha...i think its starting to make some sense. i think it will probably make a lil more sense once i break open that panel and see the wires. i think also what has me a little confused is the 4 wire, 5 wire thing. some of the drawings i have seen have at least two wires going to each light...seems like i saw some sort of colorful drawing here that had two colors going to each light....trying to find it now, its lost!

[BPFox]

I think the confusion is in the use of terms. Sometimes different names are used to describe the same thing.

On older cars and trucks the rear tail lights, turn signals and brake lights were all together using two filament bulbs typically known by the part number 1157. Trailers then and today were pretty much wired the same way. Everything was easier then since all the wiring matched up pretty good. Fast forward to today's cars and trucks and the wiring gets more complicated since many, if not most, new vehicles have separate turn signals. Instead of 4 wires you now have 5. When that is the case you have two choices. Get an "adaptor" or "converter" that will turn your tow vehicles 5 wire system into a 4 wire system to match your trailer, or just wire the trailer for 5 wires and elimating the need for the "adaptor/converter". The good news is, since you are building your own trailer, you can pretty much do what ever you want with the lights. So if you want your trailer to also have separate turn signals, you are free to do that.

What you will need to do is figure out what trailer plug you will want to use. If you are going with separate turn signals you won't be able to use a standard 4 flat plug since you are going to have at least 5 wires. I would recommend you use a standard RV 7 pin plug. Having two extra wires at your disposal is a good thing. Those extra circuits can be used for things like, trailer brakes, back up lights or battery charging.

Regardless of what you decide to do, it's good that you are asking questions now. It's best to understand all of your options so when you make your final decision it will one that matches your needs and desires.

[Joe G]

...seems like i saw some sort of colorful drawing here that had two colors going to each light....trying to find it now, its lost!

Here's a basic wiring diagram for trailers with a 4 wire setup:

[Larwyn]

I had a question about running lights, tail lights and such. I don’t have my hitch or the wiring yet but etrailer says I need this one.

What my question is..I had planned on having just two lights on the back that did braking and also did the blinking. Can I also have the running lights on each respective side blink with the back ones? How would this wiring go? Would I need something more than what etrailer says I need?

Thanks,

mandy

Mandy,

You have certainly received a lot of replies to your post here. But the way I understand your question is that you do not want separate blinker and tail lights on the back of the trailer. But would like to have the side markers function as blinkers also.

If that is the case I would just add additional side markers and wire them up with the blinkers on the rear. That would leave the original markers to act as running lights which is required. Sure the additional lights will also function as brake lights, but who/what is that going to hurt?

As far as adaptors go the one you posted would work fine and make the wiring more or less fool proof, as long as you remember to ground that white wire.

Seems you got a lot of instruction on doing something that you never intended to do. Whether it was from me or others, I'm not sure.

[rhltechie]

Hi All,

Thanks for the multitude of responses. All with very good info.

Larwyn,

I had originally intended on doing two brake lights and two turn lights in the back...just like my jeep does, seperate turn and brakes. and then i thought, hmm...it would be cool if my running lights were blinkers too....i guess i didnt really have my heart completely set on either way yet..just putting a feeler out to see how hard that might be. i think i am back to having four lights on the back. two brakes and two turns. What confuses me with this adapter above is that it was a 4 wire...which i think is impossible to do what i wanted with. the drawing above sent me into somewhat more of a confusion since it shows the brake/turn signals together in one light..so i was then in turn trying to work out in my head how the wiring would go to separate lights, specially as i have indeed looked at some lights and they all seem to have two pigtails. if i have two red and two amber and all of them have 2 pig tails what in the world are all the wires for! I think this is also a case of over thinking it...i tend to do that as well. If the yellow goes to one amber and the brown goes to the tail on the same side, whats the other wire on both of the lighs for?

I also think there was another colorful drawing around here somewhere...maybe from mike?? i cannot remember where i saw it, but it was for a setup that separated the brake/turn functions and showed exactly which wires went where....this would be why i have started savin all these images locally!

[Larwyn]

Mandy,

Okay, I have never wired a trailer for separate stop and turn lights. So if you are going to do this with two lights you would need one for the blinker and a combo stop/tail light. In that case the light for the blinker should have two wires, one for positive and one for negative, and the combo will have 3 wires one for the stop light, one for the tail light and one for negative/ground. Or I guess you could use 3 discrete lights, one for each purpose, all with two wires each. All the negative/grounds are wired together, the other wire goes to the particular function on your vehicle. On the surface it still seems like the easiest way to blink the side markers would be to use separate side markers, otherwise blocking diodes and relays would come into play, complicating the circuitry and compromising the reliability of the required marker lights.

And as others have stated, the adaptor you linked would not fit the application you are planning. You need all 5 wires. It would not be that hard to wire it up, but I do not think I have room on my trailer for all those lights. ..........

[rhltechie]

In that case the light for the blinker should have two wires, one for positive and one for negative, and the combo will have 3 wires one for the stop light, one for the tail light and one for negative/ground.

AH! thats what i was looking for! lol and now that i am going back and looking at the lights on different sites, i do see three wires from the tail portion and two from the blinker/amber lights.. thank you. i believe i do get it now. For the actual grounding portion, you mean that every single light is wired to the same ground throughout the trailer? just chained off of one another? that in turn..i assume grounds at the front trailer.

thanks again!!!