TOPIC: instrument panel wiring for Evinrude harness

Swapping in my 84 Evinrude 70 hp and having a little trouble figuring out the instrument panel power source, both switched and unswitched, to power stuff like fuel gauge, instrument lights, radio etc. The controller is the type with the ignition key/choke in the rear of the controller. The original harnesses are in good shape and everything going back to the motor is ok. I'm using the existing wiring loom in the boat and really just need to find sources for ground, switched, and unswitched 12 volt to hook to my existing boat wiring.

Looking for wiring going forward to the panel and I can find very little of it. The original harness has a small round three prong plug that plugs to the rear of the controller, then goes forward to the OMC tach.

At the tach end, five wires come out of the harness. (1 Gray, 2 Blacks, two Purples)

Three go into the tach (Gray, Black, Purple).

One comes out of the tach (Blue).

So, I have three available wires (Blue, Black, Purple)

Anyone know if that little 3 prong plug from the controller is the sole power source for the panel? And in OMC terms, is there generally a universal color code associated with a certain function such as instrument lighting, or switched 12 volt?

And last, is there a source online for some better wiring diagrams than those in the OMC manual?

I already have the OMC service manual for this motor. The wiring diagrams are big and colorful but don't cover anything that goes forward from the controller. The diagrams also are sort of modular, not saying what component any wires connect to, only which plug they plug into.

I could probably figure out those 3 leads from the controller if I hooked up the battery and started using a VOM on the leads but don't want to fry anything by energizing without the motor end of the harnesses being hooked up at this time.

Help!

Gray is tach lead (gives pulses/revolution). Blue is for light in tach (connect to navigation light switch). Black is gnd. Purple is hot or power when engine is running. You can find the purple, gray and black in the control box or connect to the colors on the terminal strip on right rear of engine block. Just hooked up OMC tach on my 78 Johnson 70. Set dial on back of tach to 6.


Did a search over on I boats and found this info for your 174206 tach.

Thanks Dave. Was that in the iboats forums? I looked around over there but didn't turn up anything.

Just my two cents Norm, but I never run anymore than gauges off the circuit from the control box. Radio, nav lights, aux lights, etc. require a separate (fused) circuit direct from the battery box IMHO. Something I was taught early on by a trusted boat guru, has always served me well. Just thought I'd share.......

That's good info Mark. On mine, a prior owner put a 6-fuse panel and a Bakelite distribution block in the cabin, under the foredeck, then ran his wires to each item from there, so it needs only one hot and one ground wire to power up everything. (Everything being very basic, just Nav lights, 2 cabin lights, instrument lights, spotlight, VHF). It does have the heavy power lead with a large inline fuse, run directly to the battery. Guess I'll keep that. I mainly want the key switched power feed for the fuel gauge so it doesn't stay on all the time.

I may add another battery after I install the 2,000 watt amp and 12" subwoofers. JK.

Norm, I have to agree with Mark. I always run two separate wires from my battery to a fuse panel under the dash. Usually pretty heavy 12 or 14 to run lights and accessories. Those cigar lighter plugins usually for gps or depth finders are ok for smaller stuff but if someone decides to actually push in a cig lighter something will pop out at you and it won't be good if it's connected to the motor ign or wires.
Cal