Unidentified wires, help! 1980 2.5 Mercruiser

[HRK]

Hi guys, I have a 1980 4-cyl Mercruiser motor. The engine harness itself is fully complete and wired, up to the large bulkhead connector on the engine. On the other side of that bulkhead connector is where the forward wiring connects to (dashboard, gauges, etc.), but on this boat it's cut after about 6 inches. I attached an image of the connector in question. I've pieced together most of the wiring using Mercruiser manual #3, but I can't identify four wires that come out of the main engine harness. I know that the wires go up to the dash area, but other than that I can't see where they connect to in any diagrams.

The wires in question are: heavy-gauge Red, Orange, Black, and light-gauge Purple-White (purple with white stripe). Does anyone know where these wires might connect to?

Thanks in advance for any help!

 

[HRK]

Alright, black looks to be the main ground for the dashboard. Still trying to find where the thick red, thick orange, and thin purple/white goes.

I suspect it's the following, but would love confirmation if anyone knows:
Thick red: main power feed to dashboard
Thick black: main ground to dashboard
Thick orange: ammeter feed
Thin purple/white: ??

 

[achris]

Here's some wiring diagrams. Can't see any purple/white. Are you sure it's that colour?

 

[HRK]

Thanks! There are so many diagrams, it's hard to know which one is the right one. For example, your diagrams don't show the solid red wire on the main connector, although my boat has one (though I assume the red/purple shown is the same as my red). However, I don't see my purple/white wire in ANY diagram in manual #3. It's definitely purple with a clear white stripe the length of the wire. I wonder if it's something the boat factory added to the Mercruiser harness for some dashboard gauge. There's also a purple/white wire on the trim switch/motor circuit, but I don't believe this is for that circuit because I also have that purple/white wire in the trim harness. I'll leave it aside for now and see what fails to work when I hook everything up!

For the thick red, black, and orange - I'll just terminate them where they are, since I'm running a dedicated power/ground to the front of the boat straight from the battery switch, and I'm no longer running an ammeter in favor of a standard volt meter.