Opus 4 Trailer Lights

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e4wesley

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Nov 26, 2021
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Cloudcroft, NM
Happy Black Friday :)

One of the rear lights on my trailer has working running lights, but the blinker and brake light function is not working.

Any suggestions?

I was thinking to check the fuse, but I do not know where the fuse for the rear lights would be and it does not appear to be in the online Opus owner's manual.
 

DonTom

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Apr 21, 2005
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Auburn, CA or Reno, NV
Happy Black Friday :)

One of the rear lights on my trailer has working running lights, but the blinker and brake light function is not working.

Any suggestions?

I was thinking to check the fuse, but I do not know where the fuse for the rear lights would be and it does not appear to be in the online Opus owner's manual.
Welcome! I see that is your first message here.

Probably not a fuse. Those bulbs are often contain two filaments. It sounds like one of the filaments is open. IOW, replace the lamp, even though half of it works. The other possibility is a bad connection at the lamp socket. Most likely NOT a fuse problem.

-Don- Bay St. Louis, MS
 

Old_Crow

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Mt Laguna, California
Yup, sounds like a bulb. If all 3 functions are working on the other side, it's not a fuse. Could also possibly be a bad ground, but bulbs are cheap and easy to replace.
 

Rene T

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Welcome. If the above idea’s don’t work, the next place I would check would be your tow vehicle receptacle. They are known to get moisture inside and corroding the wiring. Also check the screws for being tight.
You could also check and see if you have power at the respective pins using a tester that looks like a ice pick with a wire coming out of it. You would just need to know which pin is for the directional and the brake lights. Having two people to do this would help.
 

Kirk

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If you have only 1 bulb in it there are 2 elements and most likely the one for the brake/turn light is bad and needs to be replaced. If yours has 2 separate bulbs then it might be the socket for the brake/turn bulb or a bad connection somewhere.
 

Gary RV_Wizard

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And the two filaments get fed by two different wires, thus the advice to check the plug connectors and the wires as the light fixture. Stop & Turn lights are on one wire, the tail light on the other. There will be a separate stop & turn wire for each side, but a combined single wire for the tail lights on each side.
 

Kirk

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If you have the old style sockets like this one there are 2 buttons in the bottom for contact with each element and the metal sockets is the return or ground side of the lights.
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Sometimes one of the buttons will be corroded or partially melted and so cause poor or no contact. It may even damage the matching buttons on the bottom of the light bulb. That used to be the most common type of tail light socket. You may have 2 separate sockets, each with a bulb. Either way the first thing is to use a meter or test light to determine if there is power getting to the light. Have a helper step on the brake while you check at the socket. Most trailers do not have a fuse between the tail lights and the connector to the tow vehicle so if you do not have a voltage to the brake light check the connection to the tow vehicle next.

If you would, please let us know if anything thus far has been helpful.
 

CharlesinGA

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Oct 6, 2017
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50 miles south of Atlanta, GA
What kind of tow vehicle do you have. The power for those lights comes from the tow vehicle, not the trailer.

While most vehicles utilize the same circuit for the trailer as the tow vehicle tail lights, many newer ones utilize relays or solid state devices acting like relays to provide power to the trailer connector. Your tow vehicle tail lights might work fine but the trailer lights may not.

A friend has a 2015 Grand Cherokee. He installed the factory 7 pin connector kit, the vehicle already had the wiring harness, it was a matter of plugging in the connector, but it would not work. He had to pay the dealer for an hours labor to connect their "box" to the vehicle and enable the wiring. All solid state and separate from the normal tail lights.

Another example is the 2003 RAM 2500 I have. '03/'04 RAMs use one relay for running lights and one each for left stop/turn and right stop/turn. These three relays are a known problem as the relays were 20 amp rated and depending on the trailer and wiring might be running near the relay's limit. Chrysler went to 30 amp rated relays in '05. (I have already purchased my uprated spares. The fuse box has to be removed and disassembled as the relays are soldered to the bottom of one layer of the fuse panel)

Charles
 

Kirk

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Another example is the 2003 RAM 2500 I have. '03/'04 RAMs use one relay for running lights and one each for left stop/turn and right stop/turn.
I too tow with a 2003 Dodge 2500 and you make a very good point. Mine is a Cummins diesel that I bought 5 years ago from the original owner and the relays in mine failed but have been replaced with the 30A version.
 
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