Trailer taillight

Freespirit

I am trying to troubleshoot a taillight issue but am having trouble figuring it out. 

Driver side taillight:                                  Passenger side taillight:
Brake light works                                     Brake light works
Turn signal works.                                   Turn signal works
Hazard lights work                                   Hazard lights work
taillight(running light)works                      Taillight(running light) does not work

Any suggestions on what I should check?

pthomas745

The usual steps are to start with the cleaning/inspection of the 7 pin plug.  A little water or corrosion can cause this sort of thing, and in many cases solves the issue. Find some electrical contact cleaner and work on both sides of the plug, both the trailer's and the tow vehicle.

https://tab-rv.vanillacommunity.com/discussion/13100/no-lights-while-towing-7-pin-issue

MuttonChops

While it never hurts to start with cleaning the 7-Pin, since you state only the one "running" light is not functioning . . . that light or it's specific wiring would be my point of investigation.  All the "running lights" including the taillight are powered by the same 7-pin and trailer junction box connections.

Reference:(pin2 Red wire in this diagram)



Our TABs are wired (actual wire routing) very much like the diagram.  There are crimp/clamp/etc style connectors on the Passenger Side Taillight that connect to the "running lights" circuit.

On older year Rigs you can access the taillight wires by removing a small panel on the passenger side of the rear 'shelf cabinet' . . . suggest you investigate those wires, look for a poor or broken connection before considering replacing the taillight assembly.  A Voltmeter and minor DIY skills would be helpful.

Freespirit

@MuttonChops, thank you for the very helpful diagram.  I am going to study the wiring diagram and start doing some wire tracing tomorrow. I agree with you to start tracing the wire going to pin 2. 

I have connected a 7 pin tester to the tow vehicle and it tells me everything with the vehicle 7 pin is working correctly. 

You are correct, only passenger side taillight is not functioning as a running light. All other light function for that light are working. I failed to mention all side marker lights work. 

rfuss928

Have you checked the bulb in the right taillight?  It could be as simple as a burnt out filament in the bulb.

Freespirit

I want to thank everyone for their suggestions in troubleshooting my issue. I was able to identify the cause of the problem and fix it. All lights work now in their respective function. 

The cause of the problem was the blade in the electrical snap connection was not completely pushed in allowing for a complete splice/circuit connection. In the picture the connection at issue is the one with the green wire and black wire connector. 

pthomas745

How was this area accessed? 

Freespirit

@pthomas745, several years ago I removed the stock back storage unit for various reasons(not user friendly, trapped a lot of heat from the Alde) and fabricated an open bottom box frame with three separate cabinet doors. I used small tea cup hooks to attach a fine web fishnet for the bottom. Now 100% of the space is easy access and the Alde heat flows unobstructed. The middle cabinet door has a framed fish net top. 

I accessed the area by unhooking the fishnet exposing the work area. 

rfuss928

Freespirit Nice job trouble shooting.  Those quick splice connections are common in RV wiring and often a source of lost connections after time and vibration.  They will look just fine but the connection can be incomplete or intermittent.  Good to here the lights are all working.

pthomas745

@Freespirit Thanks, that mod is a good idea!