350 Horizon Randomly Shuts Down

alldodge

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The Purple goes thru the engine connector at pin 5. Check continuity between 5 and the switch.

Note, more then likely the purple daisy chains from the switch to all the gauges and then the engine connector. So anywhere the connection on a gauge is broken could be your issue
 

duped

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I have continuity on the purple, red and yellow/ red all the way back to the engine. I have voltage up to the red wire at the switch. If I move the starboard red wire over to port, everything comes on. For whatever reason it seems my red wire on this side is no good even though it has voltage and continuity to the motor. Makes no sense at all.
 

alldodge

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You have some corrosion in one of the terminal lugs. Since you have 12V on the Red wire, my guess is, when the switch is turned on it drops down in voltage.

Remove the battery cables off the batteries, the battery switch and the starter post. Clean them all up to shinny metal an look under the insulation jacket and the wire. If the wire looks green and/or corroded there is probably the issue. Anywhere along the path and even at the switch you have some corrosion happening somewhere.
 

Chigwalla

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I have continuity on the purple, red and yellow/ red all the way back to the engine. I have voltage up to the red wire at the switch. If I move the starboard red wire over to port, everything comes on. For whatever reason it seems my red wire on this side is no good even though it has voltage and continuity to the motor. Makes no sense at all.

I've seen corrosion do that - it's like putting a power resistor into the circuit. The circuit will still carry the milliamps that a DMM uses to check continuity but it won't pass any useful power. Continuity checks are very helpful but they aren't a universal test: they WILL tell you if a circuit is open but only PROBABLY that a circuit is functionally closed.

Try bypassing the red wire temporarily to feed clean power from the breaker output to that terminal of the switch.
Conversely, you could run any other device as a load off the switch-end of the red wire. An H3 bulb (handheld spotlight) will draw enough current to tell you if that's the issue. If the voltage drops right off with the bulb powered (regardless of whether the bulb lights or not), replace the red wire.
Then, to positively eliminate the breaker, pull that power off the breaker input and see if you can duplicate the problem. Be aware that, while testing, that wire will have no overcurrent protection - if it works, don't leave it like that !

It seems that, when a lot of people see a red wire, they just HAVE to tap into it for power...and that creates a lot of problems.
 
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duped

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Just re-cleaned all that stuff. Also ran a jumper from the 50 amp engine breaker up to the ign breaker at the helm and everything kicks on. I then took that jumper wire, scraped off some insulation on the red wire just after the engine connector and tried jumping it there. Nothing. So it seems I have an issue downstream of the connector, somewhere between the engine and the helm, but before the ignition breaker.
 

duped

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Great news. I will take partial blame for the issue. The previous owner had the wiring to the breakers reversed, so the whole damn time I was trouble-shooting the wrong engine...about 20 hours worth. So I reversed everything to be wired correctly and start the other side.

I get over to the starboard side engine connector and wiggle it, and it kicks on. Why was it loose? Probably because I was crawling all over that engine last week to replace the raw water pump...I even had to take the exhaust manifold off to reach it so no doubt I jacked it up. Doh.

Thanks again for everything! It kept me having hope!
 

alldodge

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Great news, happy boating, we have all done those kinds of things.

I will say, I didn't have much hair in one spot on my head from scratching it so much :)
 

duped

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For sure! I was just so baffled by this for so long. I'm still surprised that the engine was just running fine with a majorly loose connector, albeit while relying on voltage from the other motor's breaker. All the gauges worked though, no clues were given there.

I will try to enjoy the rest of the season and ignore the fact that could have found this problem in five minutes if everything was hooked up correctly when I bought it.
 
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