Replacing the MMDC with Analog Gauges

[mikey18605]

MMDC on a 2003 48 Sedan Bridge with Cummins QSM11 engines quit, - same not
available. Would like to replace with analog gauges. MMDC input shows engine input as Red White twisted pair+ & - or NEMA, plus a white wire Tach?. Inputs for Ignition both switch and key are known along with fuel senders.

Engine has sensor for oil and temp but no idea where the wires go as Sea Ray did not provide diagrams for same. Possibly they go to the Sea Ray Systems Monitor?

If anyone has done this conversion, would appreciate any help/diagrams etc.

 

[ttmott]

I don't know what a MMDC is. Do you have a Diesel View or the older Engine Digital Data Display?
If you have the Digital Data Display all of the gauges and displays were driven through a SAE J1587 CAN network.
If you have the Diesel View all of the gauges and displays were driven through a SAE J1939 CAN network then converted to three Smartcraft CAN networks.
In any case all of the sensors on the engines and gears are wired to the engine ECM's and System Integration Modules. There are no sensors that can be used for analog gauges.

 

[Riptide III]

I noticed you posted this question in two different sections/forums. Most members use the “New Posts” button at the top of the page negating the need for you to do that. As for your question, not in my lane. Sorry.

 

[Skybolt]

I'm don't know what a MMDC is. Do you have a Diesel View or the Engine Digital Data Display?
If you have the Digital Data Display all of the gauges and displays were driven through a SAE J1587 CAN network.
If you have the Diesel View all of the gauges and displays were driven through a SAE J1939 CAN network then converted to three Smartcraft CAN networks.
In any case all of the sensors on the engines and gears are wired to the engine ECM's and System Integration Modules. There are no sensors that can be used for analog gauges.

To add to Tom's post. The reason this cannot be done is you have electronic injection that is computer controlled. And the computer needs the sensor inputs to know how to adjust the injectors. The wire(s) you think you found are probably the warning indicators for the SR system Monitor.

 

[ttmott]

To add to Tom's post. The reason this cannot be done is you have electronic injection that is computer controlled. And the computer needs the sensor inputs to know how to adjust the injectors. The wire(s) you think you found are probably the warning indicators for the SR system Monitor.

And, the wiring to the Systems Monitor is from switches not analog sensors so again it can't be used for gauges.

 

[Skybolt]

And, the wiring to the Systems Monitor is from switches not analog sensors so again it can't be used for gauges.

Right, so they are floating until switched on (Open collector?).

 

[ttmott]

Right, so they are floating until switched on (Open collector?).

For the most part all sensors on the engines and other monitored things switch to ground (Bat -) in alert conditions for the SR Systems Monitor. True for both the LED display style as well as the digital LCD display style.
So, attempting to connect the SR Systems Monitor wiring to a standard analog gauge (except for a Battery Voltage gauge) will peg the gauge and damage it.

 

[Skybolt]

For the most part all sensors on the engines and other monitored things switch to ground (Bat -) in alert conditions for the SR Systems Monitor. True for both the LED display style as well as the digital LCD display style.
So, attempting to connect the SR Systems Monitor wiring to a standard analog gauge (except for a Battery Voltage gauge) will peg the gauge and damage it.

No, I get that. Connecting to a gauge isn't possible. Was referring to the alarm outputs and the possibility of connecting directly to a RIM100 for the engine warnings.

 

[mikey18605]

Believe that the QSM11 engines in fact have sensors that show resistance to ground for Oil Pressure/Temperature.in addition to sensors that go to ground for fault purposes. Believe injector control is not based on Oil Pressure or Temperature. The engines talk to the MMDC via NEMA from their ECM the MMDC converts that data and the raw resistance from the fuel tank senders to the three wire"CAN" signal that controls the tachs/4 in 1 gauges.

 

[ttmott]

Believe that the QSM11 engines in fact have sensors that show resistance to ground for Oil Pressure/Temperature.in addition to sensors that go to ground for fault purposes. Believe injector control is not based on Oil Pressure or Temperature. The engines talk to the MMDC via NEMA from their ECM the MMDC converts that data and the raw resistance from the fuel tank senders to the three wire"CAN" signal that controls the tachs/4 in 1 gauges.

Which ones? - I thought I knew that engine pretty well.
3 wire CAN signal? I need to understand that also.
If you are in reference to the Smart Gauges which were in the post 2002 boats then those gauges were driven by either a master gauge or the Diesel View or the Vessel View. Those gauge's data was provided by a two wire daisy chain from the master.

 

[mikey18605]

The three wire connection to the helm 4 in 1 and tach for P & S comes from the MMDC that is connected to the QSM11 ECM via NEMA and also the fuel senders.The three wires are Gnd/7VDC for power and the "CAN" data wire plus the light wire. All 4 gauges are unique to P & S, with the "CAN" addressing each function Tach/Fuel/Oil/Temp/Volt both P & S for a total of 10 addresses via the "CAN" signal. So when all are dead, the MMDC in the Engine room is likely bad. If the 7VDC is not present, the MMDC is bad. If the gauge lights work the ground is OK.

 

[Skybolt]

@mikey18605 What does the "MMDC" stand for? And/Or what are you calling it? I have never heard of an MMDC.

Your referencing an ECM with an MMDC. Is the MMDC the engine display? What you are describing above does not make any sense based on what I know of this.

Usually analog sensors go to the ECM, the ECM then sends via CAN (J1939) to the engine display.

Your saying the display (MMDC?) converts the J1939 back to an analog signal for standard analog gauges?

 

[ttmott]

@mikey18605 What does the "MMDC" stand for? And/Or what are you calling it? I have never heard of an MMDC.

Your referencing an ECM with an MMDC. Is the MMDC the engine display? What you are describing above does not make any sense based on what I know of this.

Usually analog sensors go to the ECM, the ECM then sends via CAN (J1939) to the engine display.

Your saying the display (MMDC?) converts the J1939 back to an analog signal for standard analog gauges?

Orlando - the first generation used SAE J1587. I have no clue what a MMDC is either. There is an Instrument Interface Module however. This is the early QSM11 Quantum arrangement (Pre-Smartcraft) -

 

[ttmott]

And this is the later Mercury Smartcraft arrangement like my boat has -

 

[Skybolt]

Orlando - the first generation used SAE J1587. I have no clue what a MMDC is either. This is the early QSM11 Quantum arrangement (Pre-Smartcraft) - ...

So they moved the auto standard of the 90's that was J1708 -> J1587 -> J1939 into the early stages of Smartcraft. Huh, never new that. Thanks for posting this and all of the schematic(s) as well. Interesting.

 

[ttmott]

So they moved the auto standard of the 90's that was J1708 -> J1587 -> J1939 into the early stages of Smartcraft. Huh, never new that. Thanks for posting this and all of the schematic(s) as well. Interesting.

J1587 is still used but only for diagnostic purposes. There is actually a J1587 port on the side of my engines. They call it a Service Tool Connection. Smartcraft and J1939 are actually compatible. The Cummins ECM feeds J1939 data into the Smartcraft network. CAN P (CAN 2) is J1939 mixed with the data from the SIM.

 

[mikey18605]

As I have explained before, the MMDC was developed by Borg Warner and later made by Medallion Instrumentation Systems They were used by Sea Ray from 2002 to ? to run the large 5" Helm gauges, 4 in 1 and the Tach. The black 6' X 6" box in the engine room gets NEMA from the engines ECM and other signals, converts same and sends a "CAN" ? data link to the gauges. A look under the helm will see a 4 wire plug to all four gauges. The wiring diagrams shows these plugs in parallel, so it is clear that the 10 separate data readouts from the gauges can only be sent over an encoded line.

As I also explained, at 20 years old these are starting to fail and no replacement is available.

This method to provide analog gauges is separate from the enginne displays such as ED-X for Cummins.

I was hopeful someone who has lost all their Analog gauges due to an MMDC failure would provide some help.

So far all the comments are from owners that do not understand the problem. Please Help!!!!

 

[ttmott]

As I have explained before, the MMDC was developed by Borg Warner and later made by Medallion Instrumentation Systems They were used by Sea Ray from 2002 to ? to run the large 5" Helm gauges, 4 in 1 and the Tach. The black 6' X 6" box in the engine room gets NEMA from the engines ECM and other signals, converts same and sends a "CAN" ? data link to the gauges. A look under the helm will see a 4 wire plug to all four gauges. The wiring diagrams shows these plugs in parallel, so it is clear that the 10 separate data readouts from the gauges can only be sent over an encoded line.

As I also explained, at 20 years old these are starting to fail and no replacement is available.

This method to provide analog gauges is separate from the enginne displays such as ED-X for Cummins.

I was hopeful someone who has lost all their Analog gauges due to an MMDC failure would provide some help.

So far all the comments are from owners that do not understand the problem. Please Help!!!!

New to me and I've seen a few (like a lot) of the Sea Ray QSM11 boats including mine. The Cummins ECM's do not transmit NMEA data; that I can for sure say. I'll also tell you that my boat is nothing like you describe. Why don't you describe your issues on Boatdiesel.com or Seaboard Marine's blog site. I'm out.

 

[Skybolt]

As I have explained before, the MMDC was developed by Borg Warner and later made by Medallion Instrumentation Systems They were used by Sea Ray from 2002 to ? to run the large 5" Helm gauges, 4 in 1 and the Tach. The black 6' X 6" box in the engine room gets NEMA from the engines ECM and other signals, converts same and sends a "CAN" ? data link to the gauges. A look under the helm will see a 4 wire plug to all four gauges. The wiring diagrams shows these plugs in parallel, so it is clear that the 10 separate data readouts from the gauges can only be sent over an encoded line.

As I also explained, at 20 years old these are starting to fail and no replacement is available.

This method to provide analog gauges is separate from the enginne displays such as ED-X for Cummins.

I was hopeful someone who has lost all their Analog gauges due to an MMDC failure would provide some help.

So far all the comments are from owners that do not understand the problem. Please Help!!!!

Just to be clear, you didn't explain any of that in this thread. I haven't read any other threads on this either, so if you did, my bad.

I don't think your going to find any help here. @ttmott is one of the experts here and has no idea what an MMDC is and either do I. As mentioned in your duplicate thread. Give Tony a call at SBMAR.com. He is the fore most expert at Seaboard Marine and MAY know what you are talking about. The other resource that might help is boatdiesel.com. It's worth the entry fee.

 

[ttmott]

I went back and looked through my data as well as the owner's manual for the 2002 480DB with the Cummins QSM11 engine option. The schematics I provided previously for the early generation are, in fact, correct for @mikey18605 situation. There is a MMDC module that is the helm gauge driver which is called an "Instrument Interface Module" in the Cummins schematics. That module gets it's data through the Main Extension Harness which is connected to the engine ECM on one side and to the Sea Ray Harness on the other side (see the Owner's manual supplement / drawing attached below). That data is provided through a twisted pair CAN network that is SAE J1587 protocol (pins 11 and 12 on connector C22 of the engine extension harness as well as the Sea Ray interface harness). And FYI - Pins 1, 2, and 9 are unswitched Bat Pos power, Pins 5, 6, and 7 are Bat Neg, Pins 3, 4, and 8 are keyswitch / start, and pin 10 is for the dimmer. I've attached the schematic from the 480DB Owner's manual; you can see the interface to the engine extension harness and the twisted pair to the MMDC.
So for the OP -

• Your MMDC is provided it's data through a SAE J1587 twisted pair CAN network, not NMEA.
• The MMDC drives the helm gauges and any warning lamps.
• The SAE J1587 CAN network and the data thereon originates at the engine ECM.
• All of the sensors and instruments on the engine interface with the engine ECM and use the engine's ECM to power them.
• The engine ECM then sends the data (temperatures, pressures, load, RPM, faults, etc) through that J1587 network.
• The engine sensors cannot be used to drive typical resistive gauges.
• If one attempts to use the engine's sensors to drive analog gauges you will definately fault the engine or worse damage the engine ECM.