Gauges Weirding Out

[access7]

2000 Legacy/Indmar 325hp. Bought the boat several months ago and during sea trial everything seemed okay as did first time I had it in the water as owner. Since then every time I run it most - but not all - of the gauges act strange, but not consistently. Example: oil pressure needle pegs or may read fine, fuel guage reads 1/8 (or not at all) when I know it should be at least 3/4, tach sticks at 500RPM (may work fine or doesn't work at all), volt meter dead, one speedo only reads 15MPH max (or doesn't work at all), other speedo goes to 30MPH just by turning on ignition (or not at all), etc. Every turn of the ignition is a new surprise for which gauges are going to read what. My first thought was the only thing they have in common is grounding, voltage and the CPU (ECM?). Unfortunately I'm guessing the latter ($$). I've check wiring as well as possible what with everything being PC boards, wire harnesses and multi-wire connectors, disconnected battery to "reboot", etc. Any ideas? Thanks.

[stagecoach]

the control box for your guages is in the back corner drivers side by fuel tank
read my post. medallian guages... 300$ fix

[access7]

I did notice the unit there when I had the boat disassembled for detailing. Figured it was dedicated to fuel pump/fuel level operation. Thanks for the assist. I'll check it out.

[access7]

After further research, it appears that the Medallion MDC-1600 instrument control module has quite a reputation for failing the late 1990's - early 2000's boats. Malibu, Supra, Moomba, Mastercraft have all used Medallion gauge sets with the MDC1600 controller. They should sell them in multi-paks because they're so unreliable. It appears that the main problem is that water from the speedo pickup tubes makes it's way into the controller and shorts everything out. Clearly a design flaw on Medallion's part. Not sure I'd trust their engineering at this point. Supposedly Bay Area Water Sports in FL has them for under $300, as does Bakes Marine in Issaquah, WA (my neck of the woods). However, after talking to Bake's it depends on the programming code. They range from $265-450 depending on the code. Sheesh....

[TX skier]

Call Medallion directly. Much cheaper to buy straight from them.

Good luck, David