I have a 7 way plug on my truck but my trailer is rigged with a flat 4 prong plug so I bought an adapter that connects the two plugs.
The break lights on my trailer seem to be bright enough & my turn signal lights work - but do not show up very bright.
I hook up the trailer and try the turn signals the flasher under the dash sounds different - like it needs a boost or something - could the flasher be the problem.

 

Ground... ground, ground
It could be the ground at the trailer tongue, at the lights or a poor connection at the plug or convertor. Convertors are junk. If you continue to use the trailer put a 7 pin connector on the trailer. Convertors are meant as a temporary fix and they corrode/oxidize and commonly have bad connections.

 

I've never had an issue with the plug converters but like Osprey said, always check the grounds first on trailers. Even a bare wire that is grounding by arc will cause issues.

 

Okay I'll check the ground. I'm just saying - I mean don't the break lights need to be grounded? Just seems like if the break lights work like they should - the turn signals should also. ??

 

The brake lights and the turn signals work off the same bulbs and the same wire. During braking both are lit together vs turn signals are separated. Since there is no resistance to make the brake lights work, unlike the flasher unit needing to pulse, there is potentially a weaker pulse during turn signal operation from a poor ground vs braking lighting.

 

Sounds to me, like you need a heavy duty "flasher" relay, and you perhaps don't have a "heavy duty" one installed right now, or perhaps it is going. You usually need a heavy duty one, when hooking up the additional trailer wiring, with its signals.

 

Agree with the others. I'd start troubleshooting by making sure the trailer had a good ground connection.

 

Thanks - I'll check the grounging on the rig.
Thanks again for your response!