Trailer Lights Gurus--Got a Question.

[Midniteoyl]

https://www.autozone.com/electrical-and-lighting/trailer-wire-harness-and-connector/p/hopkins-trailer-wire-harness-and-connector-42115/70600_0_0

The pickup does not have a "factory" 4pin trailer connector so the above is what I used several years ago to give the pickup trailer light capability. It's possible that something is connected improperly in this aftermarket device.

Another thought I'm having: Is it possible that there is a fuse receptacle in the truck that didn't have/never has had a fuse installed from the factory? In other words, the trailer lights work fine as long as the pickup lights are on but there is a seperate fuse that provides power to the trailer when the lights are OFF. Will do some Sherlock on that possibility.

Pull that adapter kit and clean all the connections. Still doesnt work, get a new one and test.

I assume by the looks of that kit that the tail lights and blinkers on the truck are the same light, correct? That setup has a bulb with dual filaments, one is normal running lights, the other is blinker/brake. Each filament is powered separately. Sounds like you are not getting power through the blinker/brake circuit and that adapter kit would be the first thing I would suspect.

 

[Midniteoyl]

Fuse Box Diagram Dodge Dakota (2001-2004)

Fuse box diagrams (location and assignment of electrical fuses and relays) Dodge Dakota (2001, 2002, 2003, 2004).

fuse-box.info

Scrolling down towards the bottom of the above page shows the engine compartment fuse diagram. I checked and there are no fuses installed in my pickup in slots C and T with both labeled in the diagram as "TRAILER TOW CONNECTOR".

I'm taking bets as to whether the trailer lights will be active without pickup lights on when I install fuses in these two slots.

If you did not have a tow connector from the factory, adding fuses will probably do nothing..

 

[jaxs]

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Installed these lights on my little utility trailer and everything works correctly except the tow vehicle lights have to be on for any trailer lights to work.

That wasn't the case with the old trailer lights and everything works correctly on the pickup to which the trailer is attached.

I can live with this but wondering if there is a way "around it"?

TIA for any comments.

Right up front,you shouldn't be expecting much from a set of lights that cost $17
#1. When you installed new lights,did trailer get ALL new wires or were some of old wires used?
#2. Did you connect every white wire from every light to 1 wire that lead's to white wire on 4 way plug?
#3. (I expect this is where your problem is) The white wire on truck side of 4 way connector should connect to frame of truck or a wire running directly to - post on truck battery. If you are relying on white wire being grounded through truck harrness,I suggest you either change it to frame OR splice into white wire with a jumper connected to truck frame. If you connected white wires from each light to trailer frame,say so and we can go from there but take care of white wire on truck first.

 

[jaxs]

With a 4pin connector the taillights and signal lines are only energized when the vehicle's are.

Whatever the vehicle behavior is will be what your lights are: so if your vehicle has no markers unless the headlights are on, the same goes for the trailer

That's right so even when truck ignition switch is off and key in his right front pants pocket,brake lights and 4 way flashers are supposed to work,no exceptions.

 

[CausticUrbanCoast]

Fuse Box Diagram Dodge Dakota (2001-2004)

Fuse box diagrams (location and assignment of electrical fuses and relays) Dodge Dakota (2001, 2002, 2003, 2004).

fuse-box.info

Scrolling down towards the bottom of the above page shows the engine compartment fuse diagram. I checked and there are no fuses installed in my pickup in slots C and T with both labeled in the diagram as "TRAILER TOW CONNECTOR".

I'm taking bets as to whether the trailer lights will be active without pickup lights on when I install fuses in these two slots.

Yes, but that is because it runs off the running light wire. The 12V line primary purpose is to charge the capacitors to power the trailers brake actuators.

 

[CausticUrbanCoast]

That's right so even when truck ignition switch is off and key in his right front pants pocket,brake lights and 4 way flashers are supposed to work,no exceptions.

They do not work that way on all vehicles, just so you are aware.

 

[WranglerX]

IF trailer is wired like diagram below then problem with lights not functioning are with tow vehicle... Only mod to drawing below would be to extend ground (white wire) to all lamps instead of using chassis as ground source... A huge percentage of trailer wiring problem are bad ground wiring/connections... LEDs are tricky and pretty finicky how they are hooked up.... Generally red is stop and & 4 way flash , black (or GRAYU) is tail, and white is ground.... Be sure you have functional match of wiring and sort of over look colors...

 

[npalen]

Yes both trailer lights are connected to white leads on trailer harness. The white lead on pickup harness is attached to pickup frame.

Test results are in:
Fuse slot "C" in engine compartment labeled "Trailer Tow Connector" is an inactive slot so no fuse.
Fuse slot "T" in engine compartment labeled "Trailer Tow Connector" was empty so I installed a fuse.
Now getting "blinking power" at trailer connector between white and green and white and yellow pins with ignition switch on but LIGHT SWITCH OFF in the pickup. Hazards working also. No power to brown on connector which is as it should be with pickup lights off.

Haven't connected trailer yet but will do and expect all lights to be working as they should. Been working on this for almost 10 hours now with about 90 minutes out for lunch and nap. Going to have a beer now if you all don't mind.

Edit: Thanks to herm0016 in post #29 for arousing my suspicion that a fuse was lacking even though is wasn't necessarily the fuse for 12 VDC power.

The weird thing is that I've been pulling this trailer around for about 20 years now and have checked the old trailer lights on occasion, even last week, and found them to be working without the pickup lights on.

I suspect that the new lights, being LED, may have had something to do with it since the fuse was missing. Just weird.

Thanks to all for weighing in on the thread.

 

[jaxs]

They do not work that way on all vehicles, just so you are aware.

Just so that we are prepared ,tell us a truck that must have key left in ignition and ignition on in order for 4 ways to work while driver is gone to have flat tire repaired.

 

[CausticUrbanCoast]

Just so that we are prepared ,tell us a truck that must have key left in ignition and ignition on in order for 4 ways to work while driver is gone to have flat tire repaired.

My 57 sure doesn't, not even a switch for hazards.

Who leaves their vehicle to go get a flat repaired??? I put on the spare and drive the flat to the shop.