View Full Version : MDC out? Speedo and fuel guage not working

05-25-2005, 06:32 PM
A mechanic (non-Mastercraft) told me that my MDC was out and that was why my speedometer and fuel guage weren't working.

Is this true?

Also, I've been told that it might just be the ground wire to the MDC that needs to be re-done...and that will fix the problem.

Any help is appreciated.

I have perfect pass so the speedo working isn't as big of an issue as the fuel guage operation.

05-25-2005, 07:09 PM
What year and model is the boat? The early MDC boxes did have a ground issue and adding a better one did cure a lot of problems. Try disconnecting the harness to the MDC and leave it off for about 5 minutes to reset. Otherwise, MC dealers are supposed to have a test harness(we got them at tech school) and this will indicate the problem-gauge or MDC.

05-26-2005, 10:53 AM
Sorry...boat info would have helped. It's an '01 X-Star.

I've been told there was a service bulletin or how-to sheet for changing out the ground wire. Is this available somewhere?

05-26-2005, 06:18 PM
You may be able to get it from a dealer, but that's the only way I know of. The first thing I would do is measure the resistance from the MDC ground wire to the negative battery terminal. Actually, that's the second thing- I would clean the terminals first.

There was a bulletin and MC has a service class for accessories and harness diagnostics/repair. All dealers should send their techs to these classes.