No power to ignition, horn, blower, or bilge after changing the alternator

[rstyll]

I have a 1993 Mercruiser 4.3LX 4bbl with no power to the ignition, horn, blower, bilge pump, etc. The power tilt works just fine. Prior to replacing the alternator, the ignition, blower, horn, bilge pump, etc. all worked fine. I replaced the original Mando alternator because it wasn't charging the batteries. I confirmed this with a multi-meter while the engine was running. I disconnected the battery, then replaced the alternator with a 12174N-1G alternator, hooking up all of the wires the same way they were on the Mando.

Using a circuit test light, I confirmed that I'm getting power at the orange, red, and purple wires on the alternator. If the 90 amp fuse on the starter solenoid were blown, I wouldn't think I would be getting any power at the alternator. I then tested the two red wires at the 55 amp circuit breaker, and I got power on both. Could it be another fuse somewhere? This old 1993 boat doesn't seem to have a fuse panel anywhere, so I suspect they are in various places inline.

 

[rstyll]

I found this link, Troubleshooting a mercruiser Starting system rev3.pdf, posted in another thread. Both terminals on the starter solenoid turned the test light on. Going to test the circuit breaker (terminal F since I already tested E earlier). Then I'll do the slave solenoid.

 

[alldodge]

There is a 9- amp fuse on the starter post (looks like a brass lug with plastic insert). If the ALT shorts out it blows the fuse

 

[rstyll]

No Title

AllDoge, thank you. I thought if I'm getting the test light to come on at all terminals on the starter solenoid and the alternator, the fuse must still be good. After your suggestion, I pulled back the insulation on the positive cable coming from the battery to the starter solenoid, and it looks like I don't even have a fuse. :embarassed: I bought this boat used several years ago, and never had a reason to check. It's quite dark down there, so I took this picture with a flash. I don't see anything that looks like a fuse. Is this even safe?

 

[Bt Doctur]

Start at the ign switch. is there power at the red wire. with key on , is there power at the purple wire

 

[rstyll]

I'll do that. For key on, is run/on position sufficient or do I need someone to turn it all the way to start?

 

[Bt Doctur]

Test the red wire for power, Y N
With key;on" test purple wire for power Y ,N
With key in "start " test yellow/red for power Y , N

 

[alldodge]

You don't have the fuse

 

[rstyll]

Performed some tests at the helm and the engine.

The red wire has power. The purple wire has power with the key turned to on/run. The yellow wire has some power with the key turned to on, but the test light is not as bright as it is when touching the red and purple wires. I was expecting the yellow wire to not have any light in the on position. When I turn the ignition key to start, the yellow connection make the test light bright as expected.

Based on instructions from Don S, Troubleshooting a mercruiser Starting system rev3.pdf, I tested the ground wires at the helm by connecting the long lead to the test light to the positive battery terminal instead. I couldn't get a light touching any of the black wires for gauges or switches (horn, bilge, etc.) at the helm. So I decided to test ground at the engine as well. The only ground I can touch to get the test light to come on, other than the ground wire coming off of the battery, is the ground terminal at the trim motor. I tested the few ground terminals I could find on the engine block, but couldn't get the test light to illuminate. Since all of this started after changing the alternator, I tried testing the ground connection on the alternator, and that didn't light up either.

 

[Bondo]

So I decided to test ground at the engine as well. The only ground I can touch to get the test light to come on, other than the ground wire coming off of the battery, is the ground terminal at the trim motor. I tested the few ground terminals I could find on the engine block, but couldn't get the test light to illuminate.

Ayuh,.... Welcome Aboard,.... Remove, clean to shiny metal Clean, both ends of the battery ground cable, both the battery end, 'n the block end,....

 

[rstyll]

Bondo, thank you for steering me to the battery. I'm happy to say that the issue is resolved, but I feel stupid. The wire had barely come out of the crimped connector for the main negative wire. The trim pump was fine since it has a separate and smaller black wire to the battery negative terminal. It was hard to see the problem with the insulating tape. Recrimped, retaped, and all good now. Must have happened when pushing the battery back a little further after hooking it back up to test the new alternator. I remember having to redo the crimp on the positive trim pump wire a few years ago.

Thank you all for the feedback and suggestions!