FWIW I had the same problem with my tuner installation.
What I thought would be a 30 min. job, turned into an hour+ job. One thing is for sure, after pulling out all wires in the loom and soldering them, I don't anticipate any future problems.

BTW the tuner reception is fair compared to the reception of my Alpine 7390.
It's nice not to have to carry two units to and from the car though.

Mk2 #105 32g blue, w/tuner