How to check ground wires?

[Dave K.]

I have the sealed capsule tail lights. The right side works but when I hook the trailer up, the directional barely flickers. I can't figure out how to remove the capsule from the bracket because of the plastic lip that holds it to the bracket but the problem may be as simple as a ground connection. Everything else and all trailer lights work.

How can I start checking the grounds wires?

Ty, Dave

 

[midcarolina]

make sure all grounds are on clean unpainted surfaces........

 

[kjsAZ]

Have seen quite often that the pig-tails of the lights were connected with regular butt joints and not the watertight ones inside the frame. These wires then corrode away......
If your running light works it is most likely not the ground wire as they share the same ground.

 

[SwarmyWench]

Touch a positive source and then touch the frame; if it don't shock ya then its ground.