2002 Ski Nautique SE edition electrical ground gremlin

[sgivens]

This seems to be a common (pun not intended) problem, but I'm hoping someone can help me target where I should start looking first.

Symptoms: nav/dash lights don't work; voltage gauge reads low (verified with voltmeter); trunk release button doesn't work

I've ran a separate line from the battery ground to the common ground block under the dash, which seemed to help a little, but didn't have the dramatic effect that it did on my '88 Ski. I re-seated a couple connections (took off, put back on) on the back of the dash, which corrected the voltage gauge temporarily. While idling underway, if the trunk release button is depressed, you can "hear" the strain on the electrical system, you can actually hear the engine (or probably the alternator) change in speed until the button is released.

Battery is strong, and the boat starts fine, which I'm assuming means the alternator is good and is doing its job of keeping the battery charged.

Any ideas where to start looking? Thanks in advance for any help.

[sgivens]

Also forgot to mention, the engine temp gauge is reading low as well.

[sgivens]

Update - I found loose and slightly corroded connectors at the trunk release button. I polished them up and put a light coat of terminal grease on them, and that seems to be working better now.

[sgivens]

Update #2 - Pulled off ground connectors on all the gauges and polished them as well. Lights are working now. Local Nautique dealer suggested moving my separate ground line from the ground block to the first gauge ground (oil pressure in my case). Also said if that didn't work, run an additional power supply from the battery to the ignition. Headed to the lake this weekend, I'll update with results.