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Electonics go out when motor is started

C

ChapZach

New member
Hey everyone, I just bought a 2005 Chaparral 190Ssi with the Volvo 4.3 Mercruiser inboard/outboard and I'm having a problem with some electronics while its on the water.

First off, everything works when in my driveway even when I start the motor with the hose. But when I launch the boat and crank up the engine, I lose power to the sound system, depth finder, horn, navigation lights and the ACC switch. But I can still start the boat and run the blower and bilge fine.

This makes no sense at all to me. Both batteries are brand new. Also, when I pull the plug after all day boating, only a few drops of water come out so I know the inside of the boat is staying pretty dry and wires aren't submurged or anything like that.

The unfortunate thing is everything works when its in my driveway so in order to diagnose the issue, I have to wait for it to happen while im boating.

When the boat first goes in the water and I'm letting the motor warm up by the dock, everything will work fine for a few minutes before it acts up. Then sometimes while cruising it'll all of a sudden start working again for a very short period of time before breaking again.

I would appreciate any suggestions or advice any of you may have. Thanks in advance.
 
I have made sure everything is tight to the battery terminals and have looked around for any corrosion on the wires but haven't found any issues. The radio does act a little funny when I play it in my driveway as in it only plays through 4 of the 6 speakers. When the radio is turned off the screen does look to have a black wave through it (like an ink stain or something) but when the radio is on I can see everything clearly.
 
Those are the hardest problems in marine life to find and fix. You likely have a loose ground wire somewhere in the system. I know you said that you checked the battery terminals, but did you pull your battery selector switch and check all of those terminals?

Often, somewhere near the batteries or selector switch there will be a large ground terminal with a bunch of wires attached to it. Disconnect all the wires, clean the terminal, clean each connecting wire and reassemble. If all of that checks out, go to your key switch and look for any loose or corroded wires there.
 
All engine starter motors draw heavy amps during cranking.
It's not unusual to see a voltage drop during this, and to see some electronics undergo a low voltage cut out for protection.

Why it does not do this while at home and on the trailer, puzzles me.

1.... which MBSS do you have?
If Perko 90* sweep, these are the worst in terms of their contacts and contact spring pressure.
If the contacts are NOT good, resistance will occur.
If you have the 90* sweep Perko, you may want to replace it with a Bluesea, Guest, Cole Hersee, etc.

2... If your instruments (VHF, sterio, DS, FF, etc) are using the OEM hull harness for their power source, you may want to run a new fresh dedicated circuit forward for these, and get them off the OEM hull harness.
Take your power from the MBSS "common" terminal, and everything will power UP and Down with the MBSS selection.

3... If you leave these on the OEM hull harness, at least pull the multi pin connector apart (engine harness interface with the hull harness), and examine the contacts. Both the Positive and Negative conductors are in this harness.

4... Make sure that your cranking battery is not only large enough, but also healthy.

5... Install the Bluesea 7622ML 500 amp ACR unit between the #1 and #2 MBSS terminals, install the remote switch, and take advantage of the "auto combining" feature for during cranking.


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