Running lights not working

Bravo16R

Member
I bought a 2020 Mallard M27 and on our second trip, the running lights quit working. I have tail, brake, and turning lights.

Also, is there a 12 volt wiring schematic for my specific camper?
 

danemayer

Moderator
Staff member
First place to check is at the connection between trailer and tow vehicle.

Here's 7 pin wiring from the Heartland manual. If you have your trailer manual, you'll probably be able to read it more clearly there.

Trailer Wiring from 2014 Manual.jpg



Heartland's manual doesn't have a 4 pin version of the wiring diagram, but here's the generic industry pin arrangement.
 

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JohnDar

Prolifically Gabby Member
First place to check is at the connection between trailer and tow vehicle.

Here's 7 pin wiring from the Heartland manual. If you have your trailer manual, you'll probably be able to read it more clearly there.

View attachment 64635



Heartland's manual doesn't have a 4 pin version of the wiring diagram, but here's the generic industry pin arrangement.

Check your vehicle's fuse box, too. The running lights are on a different fuse than the other lights. Had a similar problem some time ago.
 

Flick

Well-known member
Check your vehicle's fuse box, too. The running lights are on a different fuse than the other lights. Had a similar problem some time ago.

Yes, depending on your vehicle, John is correct. On my Ford, the running lights have a separate fuse. If you have taillights, you should have running or clearance lights. They’re tied together. Also, the trailer brake/signal lights have a separate fuse on late model vehicles.
 

Jesstruckn/Jesstalkn

Well-known member
You can jump the top 2 posts on the trailer plug and it should light up all of your marker light off of the trailer battery. You can use a wire or 2 screwdrivers. This will tell you if it's the truck or the trailer..
e6decbf5b31e69dd8c2979552b2c023b.jpg
 
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wdk450

Well-known member
If you have taillights ON ( the rear lights that turn on when your truck running/headlights are on) you should have what I call clearance lights On on the trailer. Some times all of these different light terms get confused/misinterpreted. Also, if your trailer license plate light is on, your clearance lights should be on.

Good Luck!
 
I am having the same problem with the running lights. Don't care to run without them at night or in rainy conditions. Purchased a new pigtail after developing the problem. Wired exactly like the old pigtail and put new caps and tape to make sure that it is now a quality job. Checked the fuses on my vehicle and even switched a couple around to make sure that fuses are not the problem....nothing changed. Running lights on my vehicle work fine. Brakes work, turn signals, flashers, brake lights all work fine. Did not find any fuses/breakers in the cabin of my Bighorn (2014 3270RS). Is there a set of fuses or busbar that I should be looking at to find the problem. Any help is appreciated. :(
 

centerline

Well-known member
not sure about your tow vehicle, but on my Ram pickup, the trailer clearance lights wont work when the headlight switch is set to "auto".... the switch must be in the ON position for the trailer clearance lights to work....
 

wdk450

Well-known member
I am having the same problem with the running lights. Don't care to run without them at night or in rainy conditions. Purchased a new pigtail after developing the problem. Wired exactly like the old pigtail and put new caps and tape to make sure that it is now a quality job. Checked the fuses on my vehicle and even switched a couple around to make sure that fuses are not the problem....nothing changed. Running lights on my vehicle work fine. Brakes work, turn signals, flashers, brake lights all work fine. Did not find any fuses/breakers in the cabin of my Bighorn (2014 3270RS). Is there a set of fuses or busbar that I should be looking at to find the problem. Any help is appreciated. :(

The VEHICLE RELATED lighting and electric brakes on an RV trailer have no fuses, just like any U-Haul trailer you rent. I suggest you get a 12 volt probe test light, hook up your electrical umbilical to the truck. turn on the truck's lights, and paying attention to the wiring diagrams you have been given, test out the wires to see if they are energized. You will probably have to work through the corplast under the trailer, probing again and again, until you find the disconnect point.
 

rhodies1

Well-known member
I am having the same problem with the running lights. Don't care to run without them at night or in rainy conditions. Purchased a new pigtail after developing the problem. Wired exactly like the old pigtail and put new caps and tape to make sure that it is now a quality job. Checked the fuses on my vehicle and even switched a couple around to make sure that fuses are not the problem....nothing changed. Running lights on my vehicle work fine. Brakes work, turn signals, flashers, brake lights all work fine. Did not find any fuses/breakers in the cabin of my Bighorn (2014 3270RS). Is there a set of fuses or busbar that I should be looking at to find the problem. Any help is appreciated. :(


Check the metal box on the frame of your unit where the trailer embilixal cord is attached.
All your 12 volt lights are tied together in this box, plug your cord into your vehicle, turn on your running lights on and see if their is power coming into the wiring in the box.
If their is power for the running lights reaching the box then your issue is the trailer, if their is no power reaching the wiring in the box then you may have a bad embilical cord.
 
Check the metal box on the frame of your unit where the trailer embilixal cord is attached.
All your 12 volt lights are tied together in this box, plug your cord into your vehicle, turn on your running lights on and see if their is power coming into the wiring in the box.
If their is power for the running lights reaching the box then your issue is the trailer, if their is no power reaching the wiring in the box then you may have a bad embilical cord.
Already replaced the embilical cord. Checked the pigtail & good connections there. Sounds like may be in the vehicle & not the coach. Any other suggestions are appreciated.
 

rhodies1

Well-known member
Already replaced the embilical cord. Checked the pigtail & good connections there. Sounds like may be in the vehicle & not the coach. Any other suggestions are appreciated.

Is there power from the embilical cord going into the metal box when connected to the truck.
Another question,,,do you have tail lights working on your trailer and no sidemarkers or are the side markers working and no roof markers or is neither working.
Sorry for these questions but this info will help to determine what or where your issue is in relation to the lights
 
Is there power from the embilical cord going into the metal box when connected to the truck.
Another question,,,do you have tail lights working on your trailer and no sidemarkers or are the side markers working and no roof markers or is neither working.
Sorry for these questions but this info will help to determine what or where your issue is in relation to the lights
Tail lights working. No side or overhead lights.
 

rhodies1

Well-known member
Tail lights working. No side or overhead lights.

On most units the tail light wire runs from the front to back on the right side of the trailer to the back and then across to the left lights. They also splice in at the right light for markers and roof lights.See if there is a wire laying loose in the opening which may have come loose from the tail light wire.
This is how my unit was wired, it’s a starting point .there is no separate circuit for markers or roof lights ,they are wired wired off of the tail light wiring.
 

centerline

Well-known member
On most units the tail light wire runs from the front to back on the right side of the trailer to the back and then across to the left lights. They also splice in at the right light for markers and roof lights.See if there is a wire laying loose in the opening which may have come loose from the tail light wire.
This is how my unit was wired, it’s a starting point .there is no separate circuit for markers or roof lights ,they are wired wired off of the tail light wiring.

I would agree that if the circuit is tied in with the power to the tail lights (which are working), that there is probably a single wire that has came disconnected somewhere.... a test light or wire tracer would help find the issue...

and even if you cant find where the problem is, if you can find access to the circuits, its a simple thing to install a permanent jumper between the tail and running lights to remedy the problem
 
Have you had any success in determining your problem.
No, have not resolved the problem yet. Rewired the box, checked all the fuses, breakers in the truck and replaced the plug in the truck bed (which needed to be replaced bc the cap came off a month or so ago). Still no running lights. Had my mobile RV guy onsite on Wednesday to install toppers and he is coming back Monday morning to do a quick look at the RV to see if we can find it quickly; otherwise, will make a connection with one of the lights to get them working. He seemed to know what to do for a go around.
 

Dahillbilly

Well-known member
if you do the go around remember that there is the possibility of a loose wire somewhere & it could be hot when lights are turned on. This could ground out & blow a fuse for those lights.
 
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