mddc vs. decc

[w8doc]

Sorry if this is a stupid question! Is the mddc the same as the decc? I am trying to get to know my boat-99 x22. I see the mddc under the dash with the speedo tubes going to it though they do not work. Wondering where the decc is or if it is the same thing?

[toyotafreak]

I thought that in the d-drives, the MMDC was in the back af the boat (??) In my S22, the MMDC is under the dash, on the forward bulkhead. Here's a picture of my DECC, which looks like it's under the dash, but attached to the inboard bulkhead or inside of the instrument panel area. The round hole with sunlight coming in is where the horn goes, with the steering cable as well as the wires heading into the instruments.

[w8doc]

Thanks for the picture. I assume from the picture that this is different from the MDDC. I read the how to speedo problems and there it says the tubes go from the pick-up to the gold cylinder to the MDDC. Which in that boat(cyclones d-drive I assume) was in the back. I follow my tubing and it goes to under the dash to what I think is the MDDC. Is there also a digital electronic control center DECC in the back? I just bought the boat and I do not know when the speedos last worked. One tubing is cut near the pick-up the other looks good and I cleaned debris out of it but still no speed. What should I do next to try to fix this? Reset computer? New gold cylinder? All new tubing Yes I know --buy a $100 GPS and forget it or $1000 ppass which I hope to do next spring but I still like to have everything working. I appreciate any thoughts.

[toyotafreak]

Of course the Perfect Pass is the way to go. Once you get it in, you could even remove the pickup and have the holes patched. $100 GPS is a really good investment, btw., and you'll end up using it for other stuff.

Based on what I've heard/read (no expert here), if your pitot and the tubes are clean all the way to the MMDC, there's definietely a problem in the MMDC. Do you have two pickups and two speedos? Assuming there's only one set, you might try looking at the speed display in the Message Center. If that's reading correctly, then you've got either a speedo or MMDC problem. If the Message Center's reading zero, you've got a bad MMDC.

If you decide to troubleshoot, you could always pull the MMDC and send it to Accuski for test/check.

And yes, there's two boxes, the DECC (controls accessory power) and MMDC (drives dash gauges, depth finder and optional Accuski servo).

If you don't have a battery switch (GET ONE), you should DEFINITELY try pulling power for a minute and reconnecting. This resets all three computers (incluing the Engine Control Unit).

I'm missing my picture of the MMDC, but yes, it's the one with the speedo input.

[cyclone]

Check the speedo stuff on the How_to page, there is some good stuff there. Accuski can reprogram your MMDC and provide you with a kit to move it to the trunk for better speedo response for relatively cheap >100$ or so. I would recommend spending 1k for Perfect Pass, it's like getting a new boat.

[w8doc]

Thanks for the input!! Does the MMDC run anything other than the speedos? I plan on getting the ppass i jan or feb so i am not going to put much effort into the speedos. If you are bored this winter cyclone you can head up I-85 to Lake Norman in Charlotte and provide some much needed help with the installation Hope to ski into november!!

[toyotafreak]

MMDC runs: analog and digital speedo and tach, analog and digital oil pressure, tempurature, fuel level and voltage, digital depth, and it records and displays engine hours. There may be other stuff, and ripping it out would be a pretty major undertaking.

[cyclone]

If I get some time at home this fall I'd be glad to run up there. I'm in NC next week for work, in Wilmington. I may be doing a project in Rock Hill, SC, that is right around the corner from you.

I wouldn't remove the MMDC, just get PP and you won't care anymore about the erratic gauges, you will be riding and someone else will be looking at them!