Dead Medallion Gauges on Black Scorpion

J

jmander77

Cadet
Joined
Jul 10, 2012
Messages
12
Originally posted this under the Mercruiser Section ... but this is likely a better place.

All of my Medallion gauges are dead on my 2007 Sanger V230. They do not reset or move in the slightest. I'm starting to get desperate in trying to fix this issue. I've spent hours troubleshooting wires, grounds, voltages, replaced the wiring harness under the dash and have even tried two brand new MDCs. I haven't tried new gauges simply because I think it is unlikely all of the gauges broke at the same time.

Could a faulty ECM cause this? Or could my gauges have really died at the same time?
 
QC

QC

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Joined
Mar 22, 2005
Messages
22,783
Re: Dead Medallion Gauges on Black Scorpion

Actually you had posted the other thread in the Mercury OB section. I just moved it to Mercruiser. Typically we frown on multiple threads on the same topic, but let's see how this one develops as I agree this may be the better place . . . Good luck!
 
J

jmander77

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Joined
Jul 10, 2012
Messages
12
Re: Dead Medallion Gauges on Black Scorpion

Maybe that's why I couldn't find it. I thought I had put it in the Mercruiser Inboard section. :-\

I won't be offended if you delete this thread since the other already has a reply. Your call. :)
 
Silvertip

Silvertip

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Sep 22, 2003
Messages
28,771
Re: Dead Medallion Gauges on Black Scorpion

You mentioned measuring voltages and grounds but apparently your testing is flawed. Look at the Generic Boat Wiring Diagram in the stickies at the top of this forum (not this page). You will see that gauges are powered from the ignition switch and +12 volts is daisy chained from one gauge to the next. The same wiring applies to grounds but obviously the ground does not get connected to the ignition switch. Ground is wherever you find it but ultimately it is the negative terminal on the battery. Instrument lights are also wired the same with power coming from the NAV position on the NAV - ANC switch. A tach, fuel, trim, oil pressure, water temp all require a signal from a sender. Speedometers are typically pitot driven so no sender is involved. Voltmeters also require no sender. So -- Turn the key to RUN. Now measure voltage at the "I" terminal on each gauge. Since everything quit at once, I'm betting you lost +12 volts or ground to the first gauge in the string. The very fact that the voltmeter is not working tells me that you lost +12 volts or ground. That's the function of a voltmeter -- to see what the system voltage is. Since it is wired in the same string as the other gauges, the logical conclusion is that there is no voltage and/or ground in that system.
 
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