no brake or turn signal

got ready to go fishing today,and got in my suv and notice I had no brake lights or turn signals, but the running lights worked good,I checked for power at the plug( 4 way plug).I had power on suv side but nothing on trailer side,plug looks ok....so I thought about a ground maybe so I started up the suv to rock the trailer some and notice while the suv is running all lights work,brakes,turn signal and running lights,,,,turn off the SUV and brake lights an turn signal quit working but running lights keep working, crank up the SUV and all the lights start working again.....I have never seen anything like this before,what would cause this....all lights work when the SUV is running but only running lights work with SUV off,,I have had this set up for over a year now and this is the first time I have had a problem with my lights,My only guess is to replace very thing(wires).....................unless I am missing something

Re: no brake or turn signal

johnson89 said:

got ready to go fishing today,and got in my suv and notice I had no brake lights or turn signals, but the running lights worked good,I checked for power at the plug( 4 way plug).I had power on suv side but nothing on trailer side,plug looks ok....so I thought about a ground maybe so I started up the suv to rock the trailer some and notice while the suv is running all lights work,brakes,turn signal and running lights,,,,turn off the SUV and brake lights an turn signal quit working but running lights keep working, crank up the SUV and all the lights start working again.....I have never seen anything like this before,what would cause this....all lights work when the SUV is running but only running lights work with SUV off,,I have had this set up for over a year now and this is the first time I have had a problem with my lights,My only guess is to replace very thing(wires).....................unless I am missing something

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If everything is working correctly with the motor running, go fishing and don't worry about it.

Re: no brake or turn signal

Are you sure that it worked with the SUV turned off before? Are you sure you're sure?

If the SUV has a "Powered Converter" and the power comes from the ignition circuit instead of directly from the battery; that would be the symptom.

What SUV is it?
What do you mean " I had power on SUV side but nothing on trailer side" ???

Re: no brake or turn signal

Year make and model of SUV would be helpful.

Re: no brake or turn signal

its a 2007 jeep liberty,,,,what I mean by power at the suv side is,when I unplug the trailer and test the circut I have power at the plug,for brake lights,turn signals and running lights with the SUV turned off,but if I plug it in,I have no brake lights or turn signals on the trailer but running lights still work,,,,this use to work because I always test my brake lights before I even strted the SUV ...I am worried they my all stop working while out on the road................

Re: no brake or turn signal

johnson89 said:

its a 2007 jeep liberty,,,,what I mean by power at the suv side is,when I unplug the trailer and test the circut I have power at the plug,for brake lights,turn signals and running lights with the SUV turned off,but if I plug it in,I have no brake lights or turn signals on the trailer but running lights still work,,,,this use to work because I always test my brake lights before I even strted the SUV ...I am worried they my all stop working while out on the road................

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One thing you haven't mentioned is have you checked your fuses in the SUV, the turn signals probably won't work with the key off, but the brake lights or 4 way flasher should work with the key off, at least mine do, has the pigtale or trailer plug been rewired for some reason, make sure all your fuses are ok...Maybe you have a bad ground somewhere on the trailer.

Re: no brake or turn signal

If you have amber lights OR separate turn signal and running lights on the Jeep, a standard 4 way plug will not work. There is a converter (and it may be built into the Jeep wiring) to power only the trailer lights. This may be a symptom of the converter and, in fact, nothing may be wrong.

Re: no brake or turn signal

yes it has a converter,this problem just started yesterday......just doesn't make any sense why I have power at the plug(SUV SIDE) with suv running or not but no power with the suv off and trailer plug in....at first I thought a bad plug because no power going threw it,but as soon as you start the suv up power goes threw the plug,seems impossible....it kind of hard to explain...................well I just went outside and retested and now I have no brake light or turn signals on trailer.with suv running,,,,running light still work...........I think its time to just put all new wires on trailer...this was all done a year ago and wiring all looks good...............thanks for the time trying to sort this out

Re: no brake or turn signal

well I still have problems...got the new wire installed...have running lights all the way around working......sort of have brake lights and blinkers working on leftside and none on rightside..... at the plug everything works untill I plug it in....the leftside works but if I turn on blinker or have my foot on the brake when I cranke the suv up they want work and have to turn off the suv an restart it again then they will work.....the right side only the running lights work....I have never seen anything like this in my life and have wired up at least 10 trailers..........

Re: no brake or turn signal

what a mess....just went back out and now my left blinker will not come,but if I start the suv up and turn on the right blinker 1st(yes its now working) then the left blinker will work...none of the lights will work except running light with motor off

Re: no brake or turn signal

It is time to quit messing around and get serious.
Break out the test meter!

The Yellow and Green wires power the Left and Right Turn Signals and Brake Lights.
The Turn Signals and the Brake lights are the same physical filament.

The Brown wire(s) power the Tail lights, Running lights and Side and Rear Marker Lights.
The Tail lights are a separate filament inside of the Physical Brake/Turn/Tail Lamp Bulb.
Yes! There are TWO filaments sharing one ground inside of one glass lamp envelope.



Do not get confused with which filament is lighting.
The Turn/Brake Filament is much brighter than the Tail light Filament.

Turning on the Trucks Headlights should light the Tail/Side Markers.
Turning on the Trucks 4 Way/Emergency Flashers should flash both Turn/Brake Lamps.

For Your Reference...
1. White - Trailer Frame/Ground (Opposite Gender Pin)
2. Brown - Tail/Running/Marker Lights (Sometimes Double wired as BRN/YEL and BRN/GRN)
3. Yellow - Left Brake & Turn Signals
4. Green - Right Brake & Turn Signals
5. Blue - Reverse Brake Disable Signal (Only on 5 pin Connector)



Using an OHM Meter between Pin #1 and each of 2,3 and 4 should measure close to Zero OHMS; 2-3 Ohms MAX!

Placing 12 volts between pin #1 and each of 2,3 and 4 should light each circuit.
A Battery charger can be used as a 12v power supply in a pinch.

And always keep in mind;
If it absolutely makes no sense and acts like magic; you have a ground problem!

Re: no brake or turn signal

ok did a test...ohm reading is 0 on all2,3,4.......I hooked up a battery charger and have running lights,,brakes lights turn signals,,,,,,I put a volt meter too the plug,I have power on 2,3,4 with just the key turn on ,,,,i plug in the plug an only my running lights work,no blinker or brake lights,,,,I start the suv and sometimes all lights work and sometimes only the running light will work....I have no clue what is going on with this thing

Re: no brake or turn signal

It appears the problem is NOT with the Trailer.
Unless you know different; we will make the assumption you have an aftermarket Trailer Light Converter.

Follow the Jeep wiring from the hitch connector back to the converter.
It is usually behind the driver's (Port) side Rear tail lamp housing.
Inspect all the wiring up to, and including, the splices to the Jeep's factory wiring.

Especially check the white wire from the Converter to a sheet metal screw attached to the car body.
Even if it looks good; take it off and make sure the original installer remover the paint under the lug.
Clean up any corrosion and cover the lug and the bare metal with a small smear of grease.

Try it Again!

What were the results of the Headlight/Flasher Tests?

Turning on the Trucks Headlights should light the Tail/Side Markers.
Turning on the Trucks 4 Way/Emergency Flashers should flash both Turn/Brake Lamps.

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Re: no brake or turn signal

I would also check inside the tailights. could be as simple as corrosion inside sockets. I had a similar prob with my trailer. when I turned either blinker on both trailer lights flashed. Sometimes the brake/ flasher element would stay on etc. I rewired the plug and checked all wires but still the problem. bought a brake light kit with a harness and installed the lights first(easiest part) quick wired them the old harness and voila. Worth a shot at this point.

Re: no brake or turn signal

just got home from work,,,I tried the flashers and nothing on trailer......I got a test light,with key on and stuck in the yellow wire hole the light fashes,I even stuck a 10ga. wire in the plug and put the test light on that an light flashes,so then I took the wire and put it on the yellow wire on the trailer,no flash,then I start the engine an retest and now light flashes on trailer......I will look for the ground wire tomorrow and check wires...... thanks for all the help.this thing is crazy

Re: no brake or turn signal

Still sounds like a ground issue.

You are getting an intermittent ground through the Ball and coupler.
The ground through the white wire in the connector may be good enough for the test light but will not pass the current needed for the real lights.

Voltage means nothing without the current.

Measure the Resistance from Pin #1 (White) on the Jeep connector to the frame of the Jeep; Should be ZERO Ohms!
0.5 Ohms is way too much!

Plug in the Trailer to the Jeep.
Turn on the Jeep's Emergency Flashers and Tail lights.
Measure the Voltage, Yes! Voltage!, from the Trailer Frame/Ground to the Jeep Frame.
Should Be zero volts. 2 volts is too much. Bad Ground!

Re: no brake or turn signal

ok new test...OHM test from pin 1 to frame is 0.00 voltage from trailer frame to jeep frame is .o1 with flasher and running lights on............with key on I still get no brake or blinker lights,If I start the motor they work,but if I have my foot on the brake when I start the motor they will not work....all running lights work at all times..I clean up all ground connections,even put new connecters on wires(solder) new info.....if I start the motor and then turn on blinker it works,if I turn off the motor and turn key back on that same blinker will work,but if I hit my brakes or turn on the other blinker then none will work again till i start the motor...same with flashers if I start the motor then turn on flashers they will all work,if I turn off the motor they will still work,if I turn them off then back on they will stil work,but if I turn them off then turn on a blinker they will not come back on.....I can unplug the trailer , plug in a test light and trun key on and blinkers will work but if I plug in the trailer the blinkers will only work if motor is running........

Re: no brake or turn signal

Do you have this setup in this video Trailer Wiring Harness Installation - 2007 Jeep Liberty - etrailer.com - YouTube if so you may have a bad unit or it may have gone bad if it is wired the same..I can't see that it is wired into anything keyed so that shouldn't matter except for your turn signals to work the key needs to be turned on, this is mostly standard for most vehicles

If you have a light switch it should control the power to your running lights and non-brake trailer lights on the rear of trailer, some vehicles only the front lights come on during the day time, my wifes car for instance doesn't have a light switch it's automatic, when it's dark out the back lights come on.

My guess is with all this trouble your unit may have gone bad..Or you may still have a bad ground somewhere..Or one of your connecters has popped loose..

Re: no brake or turn signal

Agree with beardeddone.

What converter is in the Jeep?
Is it a Passive or Powered Model?

It may just be defective. :blue:

Re: no brake or turn signal

First off don't know your setup without pictures, but Just a couple things I like to do to be sure i have a good ground.

1. take off the tail light lenses and inspect the bulb sockets for corrosion, as someone already said, if they are ok keep going if not you need to clean or replace.

2. your lights may ground to the light bracket through the mounting bolts, if they do loosen and retorque the nuts and bolts which may breakup any corrosion that may have cause a bad ground. If the lights ground to the frame with a wire, loosen and clean and retorque that screw to that wire.

3. my lights mount to a bracket and that bracket mounts to the frame, so I also take the bracket to frame nuts and bolts loose and retorque them which ensures a good ground in that connection.

4. my trailer has a tilt tongue and this is always an issue if you have one even if you never use it. If your lights ground to frame at the back of the trailer. meaning no seperate white wire tying every ground together and running to the front. then you need a jumper wire to jump the ground over the tilt tonge joint. very simple I have a 14 ga wire 16 or 18 inches long with a with an #10 eyelet on each end and I put an self tapping screw one end in the tongue and the other behind the tilt joint in the main part of the frame. once a season or so i back those screws out and wire brush the eyes and frame and run them back in.

4. at the front of the trailer where the plug grounds to the frame same thing usually its a eyelet with a screw back the screw out clean it and the frame where it makes connection and tighten up the screw.

I will look for picture to go with the tilt tongue set up, and post it if I can find a good one!

Good Luck!!!!