1996 7.4 LX MPI Twins. The SB engine connects and I get a readout with the software without issue. When hooking to the port DLC I get no communication until I power on the SB ignition. Then I get SB readout on the scanner instead of port!?!

I've been educated the engines can be connected within the whole boat harness and that Rinda has an option within their program to see each independently. I do not see such an option in the Scanner Pro software.

Has anyone had the same issue and how did you solve it?

Thanks for any help you can lend.
Keith

I called Onboard Diag. and Ken informed me it's the first he's heard of this issue and I was asked to call Bob and Mefi Burn.

Bob said some boats were rigged at manufacturers option with the engines sequenced together and they can be unplugged. I cannot find for the life of me anything in neither my Claymer manual nor Mercruiser manual indicating an option to harness the engines together.

Does anyone know where this connection is and/or what wire(s) are responsible for the sequencing?

Keith

this is not uncommon of 1993 or 1994 and up boat builders and or riggers and so on would link the engines together as it was called Multi engine data link harness for EFI marine engines. 2 thru 4 engines. one engine is referred to the master engine that is the engine inwhich does not have the jumper wire in the connector from the linked harness.

The harness connector is located MOST of the times depending on installed per Merc requirements should be on the starboard engine -- back side of the engine on the starboard side of that engine. If a big block around the end of the oil cooler is mostly a good place to find it.

forgot to add -- the info on the multi engine data link harness for EFI engines is shown in the wiring diagrams for all the V 8 Merc engines MEFI apps in the OEM service manuals.

the multi link harness for the engines is a 10 ft single YELLOW wire - one end has a black jumper wire in the back side of the connector in which is plugged or should be plugged into the SLAVE engine (PORT engine ) the other connector is black without the black jumper wire that plugs into the MASTER ENGINE ( starboard engine) . Again its a one wire YELLOW wire thats 10 ft in length with 2 black connectors at each end. Like I said its not UNCOMMON back in the 1990 s -- 1993 and up.


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So who want to take stabs at why builders / riggers did this link EFI engines together with one multi engine data link harness for twin engine apps. What are the reasons for this ? Lets see who can come up with the correct answers. There is one more than one reason for this adaption.

Thanks so much! This connector is the one you mentioned in post #3 atback side of the engine on the starboard side of that engine. If a big block around the end of the oil cooler is mostly a good place to find it. It should be in the same position on both engines?

Thanks so much for chiming in. What scanner software are you using? I hear the Rinda has an easy option to show the slave engine; however, it seems OBD didn't incorporate an easy gateway into their software and I've been advised (by them) to unplug the Multi-Engine harness from the slave engine to read its data.

I find it interesting that my Rinda Codemate uses only 1 common DLC PIN with the ScannerPro wire which has 2 PINS total. The Codemate has a total of 5 pins AND reads codes for each engine independently with only each of the respective ignitions on while scanning. IE Master engine ignition not required to be on to read slave engine. I assume Codemate PINS are interpolating with the DLC harness to single out each engine.

Found the connector that links the two engines and disconnected as per Bob at Mefi Burn. Now I get nothing through the port engine DLC connector even with both engine ignitions on.

As usual, "nothing ever easy!"

Keith