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1999 Sportster LX, Medallion gauges need help!


68lemans462

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I recently picked up a '99 Sporty for CHEAP! It had a cracked block and I put a new long block in it. It's a surprisingly nice boat that I'm already loving -- despite these gauges!! The gauges worked ok a couple didnt work but most did (no oil pressure or volts). I decided to check some connections and remove the medallion control box to see if the board needed to be soldered. (Board actually looked great and did not need anything). When I put it back together no go -- its dead. I went through the troubleshooting doc and wasnt able to get it working or identify root cause. I'm not getting the 7v on any of the connections. I checked connections, checked a bunch of stuff with the multimeter and I think its "dead".. After some googling -- I think I'm going to ditch these POS gauges and install some analog gauges. Perhaps I can salvage some $ by selling most of my gauges which were working...??

Are there any gauge sets that are preferred for these boats? I was looking at the Faria or similar gauge sets on Amazon for around $200. Which year of Malibu's came with airguide speedo's? Maybe I'll hunt for a pair of those? Also, how do I add a depth finder?? If anyone has pictures I'd love to see them. If I could figure out how to post pics I'd share some..

THANKS

 

Edited by 68lemans462
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46 minutes ago, justgary said:

What would it hurt to pull the Medallion box and actually solder the connector pins?  Never trust the looks of a solder joint if you suspect one might be bad.

justgary.. GOOD call. I ended up doing more googl'ing and found a youtube video on the mastercraft site showing how one method for properly and easily diagnosing the MDC. Essentially you just ensure power to orange (constant power) and purple (switched power) going into the mdc plus ground. If the gauges spin up then the MDC is supposedly ok. In the video he had the MDC hooked up to a single gauge, not the harness.

I went out to the boat and checked orange and purple wire going into the MDC with key on.. Guess what? The purple wire was dead -- dont know what this is yet but its likely at the switch. I jumped the purple and orange wires to each other and voila, I heard the magical sound of the gauges spinning up. My gauges are back to where they were initially. All work but the oil pressure and alt gauges.

I then proceeded to complete the tests in the medallion troubleshooting guide.

Step 2: if instruments dont work, unplug one at a time. -- I tried this for a short while the oil pressure gauge sat on "0" instead of pegged on 80 like usual. I can't get the alt gauge to behave but I have seen it work in the short time I have had this boat.

Step 3: measure DC voltage between pins J and K -- none

Step 4: measure DC voltage between pins 2 and 3 -- got 7 volts here

According to guide, its a bad harness... Where from here? Clean connections? It would be great if I could resurrect the 2 wonky gauges

Edited by 68lemans462
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@68lemans462 - congrats on breathing life back in to the gauge cluster.  Just my perspective and since you noted them, that Medallion cluster has never impressed me with where the needles actually point (ie:  the accuracy of the reading).  2 of the 4 primary boats we slalom / barefoot behind are equipped with the Medallion cluster and 2 have Airguides.  The Airguide & analog cluster equipped boats are much more accurate for speed & engine RPM.  Given on my boat the reading is not that critical for slalom as I run in PP mode all the time, it is good for footing runs.  And if your new toy does not have Perfect Pass, that will be your best next investment.

BTW - what does 462 stand for and does it relate to stroke or bore?

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10 hours ago, 68lemans462 said:

Where from here? Clean connections?

Definitely clean the connections at each sender and the grounds on the engine (at the rear of the heads).  I would also clean the Cannon plug at the engine and make sure it is clean.  While you have it apart, use a small blade and gently spread the split male pins to make sure they make good contact.  Put a small dab of grease on each one before you reassemble it.

Next, dive under the dash and clean every connection you can find.  The bus bars in particular can build up crud, but so can fuse holders and spade terminals.  I'm a fan of shooting everything with a fine film of spray oil once it is clean so it can help keep oxygen away.

For that matter, warm the engine and then hose it down to clean it (except the air breather), then run it again to help it dry.  Once it is dry, spray the entire thing with light oil (except for the belts and pulleys).  Don't forget to do the engine mounts and the oil pan.

After that, if gauges still don't work, test their senders with a meter to make sure they work.  @formulaben will post his famous sender placement photo here if we ask him nicely.

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2 hours ago, Woodski said:

@68lemans462 - congrats on breathing life back in to the gauge cluster.  Just my perspective and since you noted them, that Medallion cluster has never impressed me with where the needles actually point (ie:  the accuracy of the reading).  2 of the 4 primary boats we slalom / barefoot behind are equipped with the Medallion cluster and 2 have Airguides.  The Airguide & analog cluster equipped boats are much more accurate for speed & engine RPM.  Given on my boat the reading is not that critical for slalom as I run in PP mode all the time, it is good for footing runs.  And if your new toy does not have Perfect Pass, that will be your best next investment.

BTW - what does 462 stand for and does it relate to stroke or bore?

Where does one find airguide gauges? Can I get some new? Is my only option for the Medallion to find used (working) gauges for replacements, or can these be repaired? I'll go through and clean-up the wiring and connections and go from there.

I have a 1968 Pontiac GTO clone with a .030" over 455. Thats a 462.. :)

Edited by 68lemans462
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Unfortunately Airguides are like gold, really hard to find.  I’ve seen them at Great Lakes Skipper and a gauge site (the name escapes me) that should come up via google.  There are some good gps speedo options now on the market.

Nice! On the 68 GTO.  

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Well done getting it mostly going.

If you eventually loop back to it being a Medallion fault I'd just get one of these kits https://skiboatpartsonline.com/Inboard-Ski-Boat-Parts/TRD-Conversion-Kit-Medallion-MDC-1600-1/ Did it to mine last summer. Nice new gauges including GPS speedo and no medallion anymore so no chance of future issues.

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Can the Medallion volt or oil gauges be repaired? Any replacements available or do I have to hunt for working used (I know one of you out there has them) :).Both gauges do not reset or work properly when I bench tested the whole unit today. Luckily everything else is working fine 

Edited by 68lemans462
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6 hours ago, uk_exile said:

Well done getting it mostly going.

If you eventually loop back to it being a Medallion fault I'd just get one of these kits https://skiboatpartsonline.com/Inboard-Ski-Boat-Parts/TRD-Conversion-Kit-Medallion-MDC-1600-1/ Did it to mine last summer. Nice new gauges including GPS speedo and no medallion anymore so no chance of future issues.

I got this boat for $2k I don't see myself spending a grand on gauges! But thanks for the info 

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17 hours ago, 68lemans462 said:

I got this boat for $2k I don't see myself spending a grand on gauges! But thanks for the info 

$2k is a bargain!!!!

Completely understand that, however if you eventually find medallion is the fault they $1600............ 

Fingers crossed for you to find a replacement gauge at a sensible price. The 5" gauges via Bakes are $750 

Edited by uk_exile
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