2012 Sunscape 21LSV: Must Have Battery #2 to Start!

[djp53]

Here's a Fun Fact - If you want to start your 2012 Malibu (and probably other years), and you only have a single battery, you need to install it in Slot #2; installing it in Slot #1 powers up everything, including the touch screen, but the key or the touch screen engine start button do Absolutely Nothing.

My problem was, I just got a replacement Malibu Touch Command screen - yes I was one of the lucky winners that had their touch screen delaminate due to a design flaw that typically showed up right after the warranty expired, and Malibu was happy to charge me $1600 for a replacement touch screen from Meridian - no other option to operate any electrical functions on the boat other than the emergency key start and the horn.  Am I bitter - Hell Yes!  I suspect this part cost them about $500, and given the price of these boats, it's an outrage they're not willing to at least share in the cost of fixing their design flaw, let alone making a profit on it. 

So I received my replacement screen, but I only had a single battery with me to give it a try as I was getting the boat ready for the summer.  I naively installed the battery in Slot #1, and put the selector in position #1 - my normal procedure is to have my StartUp battery in Slot #1, and my Deep Cycle battery in Slot #2.  Start up on #1, drive on #1 & #2, operate while floating on #2.  As stated above, everything powered up just fine, and everything on the touch screen worked perfectly - except Start Engine.  I tried the Emergency Key Start, but it did nothing as well.  I started troubleshooting with the excellent Malibu Crew Start Up guide, and so I checked into things like the engine master breaker, and other starter-related things, and making sure I had the battery fully charged.  Not having the second battery with me, I figured I'd at least swap the one I have to Slot #2, put the switch on #2 and IT WORKED!.  

Maybe that's been pointed out elsewhere on the board here, but I sure didn't run across it as I was searching the history looking for something to try.  Anyway, I hope this helps someone down the road.  It would be a good addition to the posted Start Up Troubleshooting guide.

And it would be HUGE if anyone has an Electrical Wiring Diagram that explains how this works - possibly a missing ground relating to the starter if battery #2 isn't installed?  Why they won't publish a Wiring Diagram for the owner is beyond me!

Happy Boating,

Dave

Edited May 30, 2019 by djp53
needed additional detail for clarity