5.0 mpi mercruiser wiring harness question

[Bravo402]

5.0 mpi mercruiser wiring harness question. I found a plug that was up against the manifold riser area and it was touching them. The plug is on the opposite side of the engine where the ECM is located. The harness has wires in it then goes into this plug that only has one wire and makes a loop and goes back into the harness. Anyone know what this plug is? Is it a ground wire or does it have power on it? I just replaced the plug. The harness wasn't hurt but the plug and wire were burned and melted. Thank for the help.

 

[Fun Times]

The plug is for the shift switch interrupt system. On the alpha drives an interrupt switch helps make shifting out of gear easier and that is where you'd plug in the switch. Bravo drives do not utilize the shift interrupt switch so the wire harness needs to be jumped with the plug in order for the ignition control module system to work properly.

 

[Bravo402]

I was wondering if it had power on it and it grounded out on the manifold and thats what caused my problem with the fuse blown and the ground in the
ECM to burn up.

 

[Fun Times]

I was wondering if it had power on it and it grounded out on the manifold and thats what caused my problem with the fuse blown and the ground in the
ECM to burn up.

Yes that is very possible. The 3 wires found at that connector are part of the ECM 5 volt system. With them being shorted out could very well have been why the ECM was damaged.

As you know be sure everything seems to be in good shape and if you have a multimeter it would be best to ohms check the wiring between the ECM and switch or jumper connector end in your case then check that you have 5 volts at the connector end when you connect the ECM back up. To do that you will need page 3A-12, http://boatinfo.no/lib/mercruiser/manuals/mercruiser36.html#/96

Good luck.

 

[Bravo402]

I think we are ready to install the ECM and get on the water!!!!