Electrical problem

[onesNzeros]

I have a Mercruiser 4.3 V-6. This past weekend the boat shutdown on me while cruising down the water. Long story short, was able to get it back going by feeding the ignition power off an unused leg on the fuse panel. Been troubleshooting this the past 2 nights. With the ignition in the on position, I get nothing in my gauges and the engine will not turn over. According to the wiring diagram of my boat, that side of the ignition switch feeds back into a wiring harness on the back of the engine. That harness maps that to pin 5. Pin 5 is a direct connection to a 2 pin plug that connects to the voltage regulator on the alternator. The 2nd pin on that plug appears to map to the 50 amp circuit breaker. I have good voltage on both sides of the 50 amp. I have good voltage from the 50 amp on that side of the 2 pin plug. I have good voltage to the main power on the alternator. If I loop that 2 pin plug, essentially taking the voltage regulator on the alternator out of the picture, the dash lights up and can turn the engine over from the ignition. When I found that, I thought something must be wrong in the voltage regulator. Decided to just replace the whole alternator. Well.... That didn't solve the problem. Any thoughts?

 

[Bondo]

Ayuh,..... Do ya have 12v at the keyswitch battery terminal,..??

How 'bout the ignition terminal, with the key On,..??

 

[alldodge]

I have a Mercruiser 4.3 V-6. This past weekend the boat shutdown on me while cruising down the water. Long story short, was able to get it back going by feeding the ignition power off an unused leg on the fuse panel. Been troubleshooting this the past 2 nights. With the ignition in the on position, I get nothing in my gauges and the engine will not turn over. According to the wiring diagram of my boat, that side of the ignition switch feeds back into a wiring harness on the back of the engine. That harness maps that to pin 5. Pin 5 is a direct connection to a 2 pin plug that connects to the voltage regulator on the alternator. The 2nd pin on that plug appears to map to the 50 amp circuit breaker. I have good voltage on both sides of the 50 amp. I have good voltage from the 50 amp on that side of the 2 pin plug. I have good voltage to the main power on the alternator. If I loop that 2 pin plug, essentially taking the voltage regulator on the alternator out of the picture, the dash lights up and can turn the engine over from the ignition. When I found that, I thought something must be wrong in the voltage regulator. Decided to just replace the whole alternator. Well.... That didn't solve the problem. Any thoughts?

What year is the Boat? There is a 20AMP fuse inline with the Red/Pur wire going to the key switch

Is your man overboard stop switch in the run or ON position, and if so is the switch making connection?

 

[Bt Doctur]

Power to the system starts at the starter, thru the CB, thru the harness plug, to the dash

 

[onesNzeros]

Thanks for the replies. I guess I should have mentioned it's a 2009 Tahoe. Found the problem shortly after I posted this. It was a 15 amp fuse at the back of the motor that was blown. It was hidden pretty well.