Jimmyl: Same experience here ... works fine off the direct 12v dc but hook to the wiring harness & it only goes one direction, but most importantly, the "reverse direction now" relay doesn't work.

It's clear the motor works but either the dash switches are bad or the relay is bad. I read full current at the device but only in one polarity ... does that mean the relay is bad? Without a proper pinout it's hard to tell but I'm guessing that's the case.

More as this saga unfolds ... at the moment, the mast is up and my s.o. is happy about it so it's time for a beer .

sga