Changed RV now no signals working from RV to toad?

[sailingRNs]

Purchased 2019 Jayco Precept class A. Traded in Nexus Viper 25 that was wired to pull our toad (2020 kia soul) signals, brakes etc worked well.
Used new 7/4 cable and no signals working? Checked with shop that had done initial blue ox set up with Nexus and they said it should work fine. We are leaving before we can get it in the shop so will use one of those temporary magnetic light devices. Any ideas?

[rgvtexan]

Do the mag lights work? If not check the trailer towing fuses.

Do you have, and know how to use a multimeter?

[HarryStone]

There are relays supplied by the coach builder that pass voltage to the toad for turn/brake/running lights. When I got mine, the fuses were blown.

[F4Gary]

Sometimes I have to make sure my 7 pin plug is pushed all the way in on the motorhome.