No power at harness for hot line feeding engine

[MikeDobbs]

Hi Everyone,

So I'm a first time boat owner working my way through an electrical glitch. The boat is an 18ft bowrider with a Mercruiser 3.0lx engine. There are 10 wires that run from the dash to the engine compartment, via one large connector near the engine (this is all pictured in the attached wiring diagram).

The Purple wire (#5 in diagram) brings power from the the key to the engine, and currently has no power. I checked the entire engine side of the harness with a continuity tester, and it all checked out. Under the dash, the power wire runs from the key to a rubber connector where all of the wires from the wiring harness come together. The other side of this connector are the wires that run to the back of the boat and the large engine connector. I have continuity in the purple wire between the key and the rubber connector under the dash. However, when I check for continuity between the rubber connector under the dash and the large connector at the engine, I have no conductivity.

So, I'm not sure how to best proceed. There are many feet of wire behind the side panel of the boat running from the dash to the engine compartment, and as far as I can tell it's a straight run. Should I just cut the purple wire a foot or two away from each connector and pull a new wire? What if the continuity break is in the connector itself- is there a way to replace wiring in those things? Or do I just have to bypass the connector.

I'm a novice with this stuff, but pretty handy. I very much appreciate any help you can offer.

Thanks!

 

[wrench 3]

Those wires don't usually give problems unless the insulation is damaged. You should take a close look at the entire harness for damage, There mite be other problems waiting to happen.

 

[MikeDobbs]

So, not wanting to pull the panel off the side of the boat, I probed the insulation of the wires a little ways back from the harness at each side using the pointy end of my tester. I've got good conductivity through both connectors, the problem is somewhere in between. There's nothing on the wiring diagram between those two points, but there MUST be a splice at some point because the wire is purple with a white stripe at the back of the boat and purple at the front (there is no purple with white stripe at the front of the boat).

So it looks like I'll be running a new 12v power lines from the purple wire at the front of the boat to the good end of the purple/white wire at the back.

No on to my fuel problems!

 

[wrench 3]

Mercruiser doesn't use a purple with white wire in the engine control harness. Only in the trim harness.

 

[bruceb58]

Check your man overboard switch.

 

[Silvertip]

Why not do some real troubleshooting and measure voltage instead of continuity. Make some checks at the ignition switch:
1) Measure voltage between the "B" (battery +) terminal on the ignition switch and a known good ground. If 12 volts is present continue to #2. If not, 12 volts is not making it's trip from the battery + terminal, to the engine, up the harness to the switch. Bad/corroded battery terminals and connections are always suspect.
2) Turn the key to RUN (not start). Measure voltage at the "I" (ignition terminal) to a known good ground. If 12 volts is present power is being supplied to the engine but the harness between the switch and the engine may have an open. Check at the engine plug. Again, if ok, check on the other side of the engine plug. Continue until you either run out of points to check or you find the point where 12 volts is lost.
3)With the aid of a helper, measure voltage at the ignition switch "S" (start) terminal while your helper turns the key to START. If 12 volts is present, again follow the juice back to the starter solenoid. If 12 volts is not present on the "S" terminal with the key in start.

So once you've determined that power is present at the key switch B, I, and S terminals you have isolated the problem to the harness between the engine and control box or the problem is at the engine itself.