Disconnecting/eliminating one connection at a time, or a "wiggle test" (shaking harness wires and connections by hand until the condition changes) are common diagnostic techniques to find intermittent problems. 

On a 2016 Malibu LSV, the boat side switched ignition circuit uses a purple or purple/white wire and is connected to:

The engine harness connector 11 pin D, depth transducer connector 16 pin C, B1 Break harness pin C, kill switch connector 47, fire extinguisher connector 81A, key switch connector 56a pin A, backup camera connector 101 pin 1, shifter connector 46 pin 3, diacom connector 34 pin A, power button connector 36 pin A, stereo connector 92 pin 9, stereo connector 91 pin 9, IO module connector 10 pin 3, surf gate horn connector B2 pin F, and surf gate horn connector 76.

The engine intermediate adaptor harness ignition circuit connects to the round boat harness plug pin D, paddle wheel plug pin C, Deutsche shift harness pin 2, neutral safety harness pin A, and the rectangular engine harness pin 23.

Separating the engine harness, intermediate adaptor harness and boat harness connections may help narrow down where the problem is.

11 hours ago, oldjeep said:

The diameter they quote will be the wheel hub ID.  So if you have a caliper - just measure it on the one that fell out

OK, not sure I can get in there for a measurement without jacking her up and taking off the wheel. But I can do that.

Loose, corroded, or worn/damaged harness pins or cable connections are the most common cause of voltage drop.  Start by checking the battery and main engine cable connections and work your way towards the engine and dash harness connectors.

On 2/28/2023 at 8:56 AM, Brandonloos21 said:

Think I got the 2023+ dsp plugs figured out!

What did you buy and do.....