Odd 7 to 4 wiring problem

[mcewena]

I've recently installed a brake controller on my RV as I'd planned to tow a trailer. I have confirmed it's working with a 7 pin LED tester.

Now I'm flat towing a car and I just want marker/brake lights, when I put in a 7 to 4 adapter and use a 4 pin LED tester I get left and right signals, tail lights but no brake lights even though the 7 pin tester showed the brake light working. I've tried 2 different 7 to 4 adapters.

Any ideas?

Thanks,

[enblethen]

Do you have amber turn signals on MH and red brake lights on MH?
If so, you need to add a combiner to have brake lights on the four pin.
Verify your LED tester is not reading the electric brakes as brake lights.
If it is one like this, the brake led should only come on when the brake controller is sending power to electric brakes. If it is on without brake controller, the MH is wired incorrectly.
Circuit tester

[RinconVTR]

I think this issue is with the lights, if the tester says the plug output is good. What are you using for lights on the toad? Stand alone markers? I would confirm the work on another vehicle first, and if they still don't work return them. If you cant return them, you'll need to check how they are wired.

[mcewena]

jaycocamprs wrote:
Brake lights on a 4-pin connector are wired with the turns. A 4-way plug is L turn/brake, R turn/brake, tail/marker lights, and ground. The 7 way RV plugs also combine brake and turn.

Yes but I'm assuming a 7 to 4 adapter sends the brake power to both signal lights.

[jaycocamprs]

Brake lights on a 4-pin connector are wired with the turns. A 4-way plug is L turn/brake, R turn/brake, tail/marker lights, and ground. The 7 way RV plugs also combine brake and turn.