Hey Roberto,
If your ground is showing power then the contacts in the backside of the 6-pole socket from the Roadmaster Diode 7-Wire to 6-Wire Flexo-Coil Wiring Kit # RM-15267 have likely corroded and are touching. Once the wires are in we usually fill the rubber boot up with some RTV gasket maker # LT37467 to prevent corrosion.
You'll want to take the 6-pole socket apart and likely replace it with # RM-910030-7. You may also need to trim off a bit of the wiring if it's corroded or brittle... view full answer...