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  1. #1
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    Dec 2012
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    587

    Default medallion mdc 1600 delete and head questions

    So long story short, I started the Santera and got water in the oil. Did compression test and found that cylinder #6 was dead 45lbs. Sent the head off to get checked and it was a bad cylinder head. I have a new one ordered already. My question is where do you go for the right gakets? I might try basic power industries but would like to check else where.

    Does anyone know if you can delete the mdc 1600. Mine is bad and it is hard to justify spending 300 on a part that is a proven failure. I don't care about the speedo, just need all the other gauges and was wondering about a work around
    Function before fashion!

  2. #2
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    Dec 2012
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    Clark, CO.
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    found this on the mastercraft forum and wanted to add it for reference with all the crappy mdc units around.
    I had another thread on this subject but I figured it would be best to start a new write-up/How To thread.

    If you feel like reading through the other thread it's here:
    http://www.mastercraft.com/teamtalk/...ad.php?t=60338

    I struggled with random Medallion gauge and MDC issues for the last 4 years (Since I bought the boat). The tach would drop to 0 RPM while running and stop counting hours, the temp gauge would peg to 240+ degrees then go back to normal after a “reboot” (Super scary the first 2 times) then stopped working completely and the fuel gauge never worked right. All connections were triple checked and cleaned with no improvement. I never could gather enough concrete evidence to make me comfortable that it was definitively either the MDC or the gauges themselves even working through the Medallion troubleshooting guide. The MDC is about $290+ shipping and individual gauges that matched mine never really showed up on eBay and if they had they would have been used and still not necessarily “known good”. There were full sets available new from later year models for a few hundred bucks but there’s so much mystery around this electronic bus system that it was hard to know for sure if they’d work with the older MDC. Pretty much anyway I went on this would have been a bit of a gamble so I decided to go with the cheapest gamble of them all: Eliminate the middle man (The MDC) and go with an aftermarket set of analog gauges. I had heard anecdotal reports of this being a pretty easy project but hadn’t been able to find a write-up or anything.

    Changing gauges in general is a bit of a painful process which will take around 2-3 hrs to complete even if you were swapping in OE gauges. Swapping in aftermarket analog gauges and eliminating the MDC adds about 45 mins to an hour to this job to re-work the wiring harness. So, it’s about a 3, maybe 4 hour job depending on your familiarity with dealing with such things.

    So, here’s what worked for me. Some of this might be specific to the 1st gen Maristar 230 VRS/X-30 but it’s probably close on just about any of the boats of 2000-2005ish. The pre 2000 boats didn't have an MDC or Medallion gauges so, although I haven’t seen behind their dashes, we’re electrically duplicating the setup that the older boats would have.

    Parts/Supplies:
    -Set of analog gauges for standard American Marine senders. I chose Faria KTF001 which is a 6 gauge set of white faced gauges. I had no need for the speedometer as I have Perfect Pass but it’s cheaper to buy the set with the speedometer than to buy the 5 gauges I needed individually. I paid $172.12 shipped. Teleflex or any other brand should work just as well.
    -5-6 waterproof heatshrink 1/4” female “quick connects”
    -14-16 waterproof heatshink #10 ring terminals
    -2 heatshrink butt splices
    -Small zip ties
    -1/4” heatshrink tube

    Tools:
    -Small socket set or wrench set for removing nuts on gauges. Sizes varied but 3/8” was the largest.
    -Wire Cutters
    -Crimpers
    -Lighter to shrink the tubing/crimp connectors
    -Multimeter (Optional but you probably want to check to make sure your boat’s wire colors and what not are the same as mine)

    1) Disconnect the battery’s negative cable
    2) Remove the gauge panel:
    Lie under the dash looking up and get comfortable. You're about to contort your arms and work by feel for about 5-10 minutes while being very uncomfortable. Reach up into the cavity behind the gauges and feel around. You should be able to locate 8 wing nuts that are threaded onto studs on the back of the gauge panel. Look at the stud locations in step 4 to get an idea. Each will have a very tiny lock washer and a larger fender washer behind the wing nut. Try to grab them when you remove the nut but if things fall down in there you can retrieve them after the gauge panel is removed. After you have all 8 wing nuts removed you should be able to pull the gauge panel off with all of the gauges on it.

    Alternatively you can first remove the whole vinyl coated fiberglass dash by removing those wing nuts but I found that that's much more of a pain vs. just reaching for the wing nuts if all you need to access is the gauges themselves. I’ve done this at least 4-5 times now.

    3) Disconnect all gauges and check engine light and remove the gauge panel. These are all removable connectors so no need to cut anything yet.


    4) Swap your aftermarket gauges on the panel. This is pretty self-explanatory. The new tach had a little selector where I had to select the right position for an 8 cylinder engine.
    [img]http://www.mastercraft.com/teamtalk/attachment.php?attachmentid=112500&stc=1&d=1402101 670[img/]
    5) Cut off all of the 5 pin gauge connectors where the old gauges connected. This is the point of no return.

    6) Remove the yellow wire from the harness or just tape/heatshrink them and leave them in. This is the signal/bus wire and is no longer needed. I chose to remove it and “rebuild” the harness (More on that later)
    7) Disconnect and remove the MDC. There are some short adapter pigtails for the 18 pin connector and the 5 pin connector. I just left those adapter pigtails on the MDC. If not using a speedometer plug or remove the pitot tube (unless you like wet feet/carpet)
    Remove the plastic wire loom from the MDC harness
    9) Pull the MDC and gauge harness up through the hole in the dash (Where the gauge panel normally resides)

    10) Cut off the connector with the gray, pink, tan, light blue, etc wires (The upper one in the picture above). I'll refer to this as the "MDC Harness" from here on.
    11) Extend the tan wire over to the temp gauge position
    12) Extend the gray wire over to the tach position
    13) Extend the light blue wire over to the oil pressure gauge position
    14) Extend the pink wire over to the fuel gauge position
    Note: On steps 10-13 there was way more wire in the factory harness than I would need. I did not need to add any additional wire for any of this project. The orange wire is not used. Cut it off/coil it up and tape or heat shrink it off so it doesn't ground out.
    15) Cut off the gauge harness connector with the black/yellow stripe, red/white stripe, etc. wires on it (The lower one in the pic above). I'll refer to this as the "Gauge Harness" from here on.
    16) Butt Splice the black wire (Ground) from the MDC harness to the black/yellow stripe wire from the Gauge Harness.
    17) Butt splice the purple wire (Ignition switched +12v) from the MDC harness to the red/white stripe wire from the Gauge Harness.
    Note: Steps 16 & 17 are necessary because with the MDC in place ground and ignition switched power were passed through the MDC. With that removed you need to re-complete those circuits. I had a few feet of extra wire between them that was removed during that process as the wire didn’t need to go down to the MDC on the kick plate and then back up to the gauges.
    Last edited by 2500HD; 04-11-2015 at 09:10 PM.
    Function before fashion!

  3. #3
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    Dec 2012
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    Clark, CO.
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    1 Strip and crimp on a 1/4” female on each dark blue wire in the gauge harness. This is tied into the NAV light switch and is for the gauge face backlights. There were warnings on the gauges to not allow this wire to touch the sender signal wire so I opted to put heat shrink over the terminal itself to insulate it from adjacent terminals.
    19) Crimp #10 ring terminals on each Black/Yellow Stripe (ground), Red/White Stripe (ignition switched power), and the appropriate signal wire for that gauge position (i.e. gray for tach, pink for fuel, tan for temp, light blue for oil pressure). The volt meter doesn’t have a “signal” wire just +, - and + for backlight
    20) Clean up your harness and prepare to reinstall the gauges. I had to re-terminate power and tach signal for my Perfect Pass as those were previously spliced in further down the line. I put heat shrink over the speedo wires since I wasn't installing it and the PP doesn't use those.

    21) Connect all gauges per the instructions
    22) Reconnect battery and test basic function
    23) Close everything up by reversing the process in step 2

    I tested by running it at home and all of my gauges work now except the fuel level. I apparently have a bad fuel level sender on top of everything else as when I test it with a multimeter it shows 270 ohms (i.e. very empty) regardless of fuel level (It’s supposed to be 33.5 ohms full and 240 ohms empty). I’ll be replacing that sender and I’ll hopefully be done with gauge issues for a few years. If nothing else at least this setup is 50% easier to troubleshoot without the MDC in the mix. It’s either the sender or the gauge now. With the MDC/Medallion setup with any “gauge” malfunction it could be the MDC, the gauge, the sender or even another gauge causing “noise on the bus”.

    Technically this should work fine for the 2006+ newer boats too but with the billet and molded plastic dash panels you may have cosmetic issues making these look right. I’ll leave that up to some of you guys with the fancier boats to figure out. I’m also unsure if ballast gauges would come into play on those boats as well.

    Although completely unrelated to the MDC my depth sounder was generally unreliable. I replaced it with a matching one in the process.

    The look and feel of the gauges is of similar quality to the OE Medallion gauges. I think the overall look has been improved in the process for my particular boat. Now everything matches. I'll report back when I have the new sender installed and I've done an actual water test.

    In the end it cost me about $185 with the terminals and what not (Not counting depth sounder or the broken fuel sender) to replace my 5 gauges. I likely can sell the unused speedometer and pitot kit to recoup some of that cost. That's over $100 cheaper than just the MDC or an old stock set of medallion gauges and certainly cheaper than gauges + MDC by a large margin.

    Before:
    Last edited by 2500HD; 04-11-2015 at 09:13 PM.
    Function before fashion!

  4. #4
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    Dec 2012
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    After:


    After with engine running and backlights on:
    Function before fashion!

  5. #5
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    Dec 2012
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    Clark, CO.
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    Well i ripped the mdc out of my boat today and all i gotta say is medallion must have one hell of a sales person. The sending unit goes from the engine to the circuit block at the drivers seat then back to the rear compartment to the mdc then back up front to the gauges. All i had to do was go from the circuit block to the gauges and eliminate the middle man. everything works great.
    Function before fashion!

  6. #6
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    Aug 2009
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    London, Ontario, Canada
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    Pictures would be awesome if possible for others to do similar if possible
    2009 21v Worlds 340 Cat
    run your engine after you change the oil
    Doug

  7. #7
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    Dec 2012
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    Clark, CO.
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    I'm afraid i was in a bit of a rush to get it done so i could fire up the boat and adjust my timing. So i didn't take any pictures. And it started snowing so i didn't get to adjust the timing either.lol
    It was pretty easy though. just follow the mdc wires to the circuit block and cut them off about 5 feet before the connector then just use the wires specified in the above wright up to wire your gauges.
    10) Cut off the connector with the gray, pink, tan, light blue, etc wires (The upper one in the picture above). I'll refer to this as the "MDC Harness" from here on.
    11) Extend the tan wire over to the temp gauge position
    12) Extend the gray wire over to the tach position
    13) Extend the light blue wire over to the oil pressure gauge position
    14) Extend the pink wire over to the fuel gauge position
    Function before fashion!

  8. #8
    Join Date
    May 2011
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    1

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    Quote Originally Posted by 2500HD View Post
    ...all i gotta say is medallion must have one hell of a sales person.
    I'm the OP from the mastercraft post. I became a member of all of the various inboard forums years ago when I was looking for a used boat and heard this made its way over here. Glad this is working out on Supras too.

    After becoming intimately involved with the Medallion gauge system I had several hypothesis about why it was appealing to the OEMs but all of them ultimately were disproved except one:

    1) Simplified wiring/install during manufacture- I probably eliminated 15 ft of wire and obviously the MDC during the process of removal and didn't have to add a single inch of wire for my particular application. Theoretically they could have mounted the MDC by the engine and then only routed one bus wire up to the console for the gauges which would have saved wire (Albeit inexpensive 16-18 gauge wire) but I haven't seen any builds where they did this. All wiring from every sender runs all the way up to the console then just plugs into the MDC instead of the gauges directly. The standard gauges I used required a little more thought to connect but they do make "connectorized" analog gauges that would lend themselves to "plug and play" harness manufacture where they'd just plug the gauges in on the assembly line the same way they'd plug in the Medallion gauges. In the manner I've seen it implemented there could be no savings of time or money during manufacture with this system.

    2) Consolidating sender data and giving better information and/or making decisions for the operator: This is where I really expected to find the value of this system. Water temp climbing and/or low/high oil pressure? Display a useful message on the dash and possibly take protective action for the operator against engine damage. Not only does the system not tap into the "Check Engine" light (That goes straight back to the MEFI computer. Mine functions without the MDC as it never passed through the MDC to begin with) but it has no provisions on the gauges to display such information. There is also no electrical path from the MDC to talk back to the MEFI or cut ignition to shut down the engine. The MDC/Medallion gauges, at least as implemented on my boat, is simply a 100% direct replacement for "normal" gauges that offers 0 additional functionality.

    3) Other than that I only have a conspiracy theory left. It's simply to confound the shade tree mechanic and drive them to the dealer for repairs/parts. Why else would you implement a more expensive, more difficult to install during manufacture, more complex system that offers absolutely no additional functionality? At a minimum they have you on the proverbial "teat" for the life of the boat for OEM gauges and parts that otherwise could have easily been replaced with aftermarket offerings.

  9. #9
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    Dec 2012
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    Clark, CO.
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    Choice number 3 is the only one that makes any sense to me. My Mdc was mounted on the transom so each wire had 30ft it didn't need to travel!
    Function before fashion!

  10. #10
    Join Date
    May 2011
    Location
    Seattle, WA
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    12

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    Quote Originally Posted by Jeff d View Post
    I'm the OP from the mastercraft post. I became a member of all of the various inboard forums years ago when I was looking for a used boat and heard this made its way over here. Glad this is working out on Supras too.
    Thank you both for the info and confirmation that this is pretty easily doable. My only concern is that the 'rim' lighting on the Faria gauges might look super 80's (I use my boat a lot at dusk and night).

    Would one of you please share a photo of what the gauges look like at night with the lighting on? I can't seem to find one anywhere on the 'net. Apparently most people don't boat at night?!
    1999 Supra Santera - my 1st boat!

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