Hello all, in my checking of actual engine hours using my Rinda software vs the Helm Hour analog gauges that are not 100% accurate. I noticed that both engines come up as "Master" and NOT as ("Master"/"Slave") on the bottom left of the screen when communicating with the engine. Is this an issue or a non-issue? Any guidance would be greatly appreciated.
Information of Vessel:
1999 Carver 406
Engine Starboard Mercruiser 7.4L MPI MIE V-8 gasoline naturally aspirated engine - 330hp SN- 0L303931
Engine Port Mercruiser 7.4L MPI MIE V-8 gasoline naturally aspirated engine - 330hp SN- 0L303934
MEFI 3 ECM on each Engine
I found this text in a publication named
"MerCruiser EFI Engine History and Major Changes"
"The engine control module (ECM) on all 1996 and newer model year EFI engines has the
“Power Reduction Mode” disabled. Because of this change, it is important that 1995 (and
older) models not be intermixed with 1996 (and newer) models on multiple engine boats. It
is important that all of the engines in a boat have either the power reduction mode enabled
or disabled, but not a combination of both.
The 3-pin Master/Slave connector and the 2-pin Safety Lanyard Stop Circuit connector have
been removed on some 1996 and newer MEFI 1 models and all MEFI 2 and MEFI 3 models.
On these newer models, if the Master/Slave functions are desired, it is necessary to build a
custom data link harness and connect it between the DLC connectors on the engines. The
serial data terminal (Pin G, orange [or orange/black] lead) on the data link connector
(DLC) of both engines must be connected together and the master/slave terminal (Pin
H, yellow lead) on the Slave engine’s DLC must be grounded."
I read this as Master / Master is OK
1999 Dual 454 with Mefi 3 ECM - Master/Slave relationship
- kgarguilo
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1999 Dual 454 with Mefi 3 ECM - Master/Slave relationship
Kevin G.
Mobile AL - Fairhope Docks Marina
1999 Carver 406
Mobile AL - Fairhope Docks Marina
1999 Carver 406
- g36
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Re: 1999 Dual 454 with Mefi 3 ECM - Master/Slave relationship
I wouldn't think it's a issue. My 405 is mefi 1 and I disconnected this wire when I installed my fox mefi gateways on my crusaders.
1997 Carver 405
Crusader xli
The Black Pearl
Soddy Daisy Tn.
Crusader xli
The Black Pearl
Soddy Daisy Tn.
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Viper
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Re: 1999 Dual 454 with Mefi 3 ECM - Master/Slave relationship
I strongly doubt it would be an issue. Do you have Smartcraft?
- kgarguilo
- First Mate

- Posts: 180
- Joined: December 5th, 2022, 2:41 pm
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- Location: Mobile, AL.
- Has thanked: 197 times
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Re: 1999 Dual 454 with Mefi 3 ECM - Master/Slave relationship
No, all manual controls. One day soon, I will add Fox Marine Mefi 3 nmea2000 interfaces for my Garmin 8612. That is as fancy as I will get on this boat.
Kevin G.
Mobile AL - Fairhope Docks Marina
1999 Carver 406
Mobile AL - Fairhope Docks Marina
1999 Carver 406