Quest for accurate gauges

[cyclone]

if you lie on your back and look up under the dash, you'll see the DECC (I call it a digital switchbox) It is a black box, about 1" thick and about 5"x 7" It has a bunch of orange wires going to it, and studs on each end where the 12vdc and ground come in from the battery. It is basically a box of relays that are switched by the switches on the dash.

Your MMDC (gauge computer) is mounted under the dash, on the left (port side) and it has two small rubber hoses going to it. Those are the speedo tubes. It is also a black box but it is about 6" square.

[toyotafreak]

Here's what the label looks like:

http://www.elesman.com/epic/epicphotos/displayimage.php?album=13&pos=246

[sailtl]

I did all the recomendations and still them same senario. Everything works fine for about a hour then all the gauges die like turning off the key. Turn on the navigation lights and everything is fine. If I ever figure this out on our Epic 21 I will report back.

[cyclone]

I'd bounce it off Capt. Rick, but it sounds like the DECC box should be replaced.

[sailtl]

I have some schematics and contact information for Medallion I would like to pass along but I do not know where or how to send the Microsoft word documents and emails to forward. Any assistance would be nice.

[lesman01]

Sailtl, Check your hotmail account.

[sailtl]

I thought the info I provided would pay off and it did with the addition of the install guide for the gauges in our boats. I will not start trouble shooting my gauges that do not work unles the navigation lights are on and post information about the cure. Once again thanks to everybody for providing sound and accurate information for our boats

[sailtl]

I do not have a MMDC on my 1999. Will Borg Warner give up information on the older MDC units? Last post had an error. It should have stated that I will start trouble shooting my guages with the information.

[sailtl]

Started working on my gauge problem (gauges only work when nav lights are on). It is not a ground problem. Next step will be battery postive to MDC unit. I will keep you posted.

[cyclone]

That diagram you obtained, SailTL, is EXACTLY what I have been looking for to troubleshoot my problems. My symptom is that my voltage is normal at idle, and decreases to about 10 vdc at speed, causing constant voltage alarms. I measure 10 vdc under the dash, and I want to verify the symptom at my MMDC, which is in the trunk. I didn't see that inline fuse, that is where I want to do my first tests. Thanks for the info and the Medallion contact, I'll definitely hit them up them as my testing progresses, and will also post the results here.

[sailtl]

I had a voltage drop problem also. I found that problem as a loose connector at the circuit breaker on the engine. This is the circuit breaker for the alternator. It is on the panel for the manual fuel pump run and the other big breakers. You may have a loose wire at one of the breakers.

[cyclone]

Hmm, that is very interesting. I will look at that. BUT I did crawl up under my dash and measure some voltages under static conditions. I had 12.6 at the batt, 12.4 at the DECC, and 12.0 at the supply to the MDDC at the underdash connector, before the 12 ft run to the trunk. That's with the gauges and ignition powered but not running.

I could not find the inline fuse. It may be further up the harness behind the big sidepanel where I can't reach. That is where I'd like to test for voltage drop. It would not surprise me if it is corroded. I will test, under load, the 12vdc going to the MDDC at idle and at WOT or FWO to you rednecks, you know who you are......

I did find the Accuski pigtail, tied up and going nowhere. The output to the solenoid was sent from the MDDC through this cable. The 12vdc coming from the dash is via 16 or possibly 18 gau. wire, and the output to the solenoid is about the same. WIMPY. They use a different actuator than PP, it is  rotary solenoid stepper, it must have very big steps.

[Bitzco]

Who you callin' a redneck. From what you is a sayin', you gotta know what FWO is to be a redneck. I ain't sure what WOT or FWO is, so you cain't ba a callin' me no redneck. Besides, them rednecks cain't conjurgate verbology nor spell worth a dang.

[cyclone]

Wide F******  Open

[cyclone]

Bitz, why did you assume I meant you? It is a total redneck thing. I mean down home hell yeah redneck thing. Owning 2 '68 chargers, one B5 blue with a 383 and bench seat, one b5 blue with a Hemi and a 250 gal stainless tank instead of a trunk and back seat. In the same garage:) I know the guy.