1976 Merc 120hp wiring problem

[neller]

I am getting 12.5 volts at the battery, but only 1.6 volts at the ignition switch. Turning key to accessory I lose power to everything, 0 volts at ignition switch. Turn key back to off, have dim light at blower switch (should be off) and again 1.6 volts at switch. Ideas?

 

[Bondo]

Ayuh,.... Sounds like awhole lotta corrosion on awhole lotta connections,...

Start at the battery, 'n sand to clean shiny metal Clean, each connection in the circuits, Includin' the Grounds,....

 

[kenny nunez]

In case the above remedy does not help replace from the engine ground and the + connection on the starter the red & black wires with #10 wire to the ignition switch and the instrument panel ground. If that boat ever took on a lot of water "SUNK" with a live battery the wires will be corroded and needs to be re wired.
It is no big deal to re wire a boat. A boat that age is due for that by now even if it never took on water. You can buy a good used engine to panel harness or get a new one for a little more.

 

[neller]

Thank you for the replies. I should have mentioned it was an instant problem. Everything good, lots of cold ranking amps, bright lights. Then, nothing.

 

[neller]

My boat had been rewired previously, and the whoever rewired it had taken direct power to the wrong side of the accessory fuse block. I rewired the fuse block correctly, and with ignition on power, and it is fixed. Thanks for the help. Wiring problems always seem to be only found on your back with hands crammed into small places. Best to do it on a 90 degree day!

 

[harleyman1975]

LOL funny they never break down when it is easy and comfortable to work on them...or when you have access to all the right tools.