Speedometer reads zero suddenly, anyone with a similar issue?

[hemlock]

Hi ballers,

I have a 2003 Malibu Sunsetter LXI and I'm reaching out to you hoping anyone with a boat with a paddlewheel speed sensor came across anything similar. Malibu or otherwise. I've made a post to themalibucrew forum HERE. You may have already read it if you frequent that forum, and it has more details.

But here's a quick summary:

Original owner, speedo always worked until it didn't a few days ago. Just reads zero. Confirmed the paddlewheel spinning by hand does send a change in voltage from 0 volts, to 12 volts with a quarter turn of the wheel.  Paddlewheel has no visible damage. The MDC computer under the dash is getting this signal as the connectors and wires all look good. Tested with Multi-meter. Tried different plugs from other gauges and eventually even replaced the gauge with a brand new one. Same thing. Have not tried a new paddlewheel yet.

My last hope is that either the paddlewheel itself is sending to high of voltage (0-12 volts {engine off, key on} and 0-14 volts while engine running) as the wheel spins and the MDC computer won't compute that properly, or that the MDC itself has a failed component inside related to the speed signal. All other functions of the dash work normal.

Anyone have a similar issue?

Thanks.

 

[jpwhit]

Given all the tests you've done, it's pretty likely failing components in the MDC. And if it's not the MDC failing now, it will be in the not so far off future. If it were my boat, I'd go ahead and start the conversion away from the MDC to gauges that don't depend on the MDC. Since your speedo is broken now, I'd just go ahead and replace it with a GPS based speedo. You could go ahead and buy a full conversion kit now, and just install the speedo until you start to have other gauge issues. Or you could just buy the speedo now, but it would be worth it IMO, to try and get a speedo that will match later if you have to replace the other gauges. 

Does the boat have speed control? If so, is that working? Is that also getting it's speed input from the paddlewheel or is it GPS based such a Perfect Pass Stargazer?

[BraceMaker]

One speedo or 2?  

There are of course adjuster buttons somewhere on your boat as well for the speedos.  This could vary but the whole point of the medallions was that airguide speedos were NLA and they needed two adjustable speedometers for tournament boats to be approved.  So most of these boats have rocker switches somewhere on the boat.

This means there are two things you need to find, A - where are the rocker switches find them and tap the up button a number of times and see if your gauge comes on.  And B: in this application usually there were two speedos one got pulled to install the PP, but there should be two speedos and technically they should both be separately adjustable with rocker switches, so there is probably a second wiring harness loom behind the dash for the speedo.  If so I would switch it over and verify.  

 

[S1Pitts]

There was a thread here from a while back that had a tutorial on how to repair the Malibu guages of that era. I myself have been looking for it as I have a friend who's speedo quit as well.

They use an electronic clockwork the same as GM cars/trucks. They just suddenly quit working. The tutorial explained how to open up the guage and replace it. I just replaced 4 of them on my wifes 2007 car at a cost of $12/clockwork as opposed to over $1K for a new speedo cluster which is now special order and a 6+month wait. I found the clockworks at WalMart of all places.

[jpwhit]

@SiPitts is correct about how these gauges work. And a pretty typical failure is the stepper motor (clockwork) fails in the gauges themselves. They aren't that hard to fix, but it's a little tedious. The MDC provides the signals to drive the gauges and they also seem to fail somewhat consistently at a certain age. I suspect they have the type of electrolytic capacitors in them that dry out and fail after a certain age. I've never taken an MDC apart to investigate the cause of the failures. 

Fixing it depends on whether the problem is in the gauge or in the MDC itself. Often the gauges are daisy chained together. So, if one gauge on the same daisy chain isn't working, and you move its position in the daisy chain and it still doesn't work, then that's almost always a problem with that gauge. If the gauges after a certain gauge on the same daisy chain do not work, then the gauge before isn't properly passing the signals through. I think some MDC have more than one output so they can be multiple chains, or certain gauges may have a dedicated output. If all the gauge suddenly quit working, that's almost always the MDC itself has failed. 

[Deke]

A number of years ago the gauges on my 99 RLX went out due to a lightning strike close by. I was able to get a replacement MDC through Bake's Marine. If I recall these were made to order by a third party supplier for older boats. It wasn't all that expensive and, at least, worth a call.

[hemlock]

Thanks for the replies!

Here's a pic of the dash, with key on, engine off.

I have replaced the speedometer with a brand new one. And same thing. The cluster gauge with oil, temp etc all works.

I replaced the RPM gauge with Stargazer, so the boat is usable, just hate having one gauge with a dead needle. And I could put the RPM gauge back in to replace the speedometer gauge, but then I lose the little LCD screen that shows the depth, hours etc.
I do also have the 2 rocker buttons by the ignition switch (one to change the LCD display info, and one to slightly adjust the speedo needle up or down if it's slightly off) 

I wonder if those buttons could somehow disable or set the speed needle to zero, or disable it somehow by holding it down?

Maybe I played with it one day and accidently did something?

 

 

 

[BraceMaker]

Yes those are the speedo calibration switches.  The whole MDC gauge fiasco was simply because to be a AWSA approved towboat you needed two adjustable speedos.  Airguide said they were done making them and they were really the only adjustable ones on the market so there would be no boat meeting the AWSA spec.  Medallion said they could do it and have electronic rocker switches.

 

So yes try arrowing up those rocker switches I know in MC world they can cause a gauge to not work at all.

[hemlock]

2 hours ago, BraceMaker said:

So yes try arrowing up those rocker switches I know in MC world they can cause a gauge to not work at all.

Interesting, Okay thanks. I might pop over to Teamtalk and search through some posts.

[BraceMaker]

https://www.bakesonline.com/media/resourcelibrary/MedallionII_Troubleshoot.pdf