3k SCR No power to port, gauges, etc.

[MaximusBoatimus]

Hey All,

After winterizing last fall went to start her up, first mistake was I failed to add gas to the fuel/water filters after changing them, finally got the starboard side to start up and purr. Port however after placing the key in the ignition I had power for a second until I engaged the start position with the ignition then nothing. Absolutely nothing. One of the batteries was loose at the terminal. I'll double check but I believe the batteries are 2 years old.

2 Merc 5.0 305's, carbed. Winterizing was an oil change 2 both, 2 water/gas filter changes, coolant drain, batteries topped off, gear lube to the lowers, had her shrink wrapped as well.

The gauges don't power up, tried to jump the starter solenoid nothing, so I figured I would change that first. Tried, no change. Batteries read 12.58v on starboard side, port read 11.95v with the multimeter.

Checked the 20 amp fuse(with multimeter), on the fuse board under steering wheel, pressed the 50 amp on the motor at least 40 times. Is there another fuse I may have missed?

I tried swapping the ignition wires with the starboard side and still no change. I'm at a loss, and would rather not pay $110/hr for the fix, especially when I wont be present to see how it was fixed for the future if it were to happen again.

Any help would be greatly appreciated.

[RandR]

Is tHe main ground corroded? Do you have the 12 volts from the battery to any ground on the engine ? No indicates bad ground

[mmwjr]

If you have verified the battery cables are clean and tight at both ends including the negative connection to the engine then try the following.

First use your meter to see if there is 12V on the B terminal of the ignition switch.

No voltage, check to see if you have 12V on both terminals on the engine breaker.

No voltage check for power at the fuse on the starter.

If there is power on the ignition switch verify the shifter is in neutral and see if 12Vs exists on the I terminal with the key in the run position and on the S terminal when the key is in the start position.

[MaximusBoatimus]

Red wire is 12v I believe on ignition correct?

I'll have to double check where the ground to the motor is.

[mmwjr]

Correct the red is 12V on the B terminal. The purple (switched) gets power when in the run position and the other wire goes the slave soleniod and provides power when the key is in the start position.

The battery negative cable should connect to the engine on one of the flywheel conver bolts.

[shrew]

Stupid question. Everything you describe sounds a lot like the batteries are simply dead. Are they holding a charge?

[MaximusBoatimus]

Originally Posted by shrew

Stupid question. Everything you describe sounds a lot like the batteries are simply dead. Are they holding a charge?

Not stupid, batteries are in parallel, engine on stbrd starts, runs. Port doesn't, batteries has 12.5v, 11.9 on other.

Tomorrow I'm going up to check a few other things. Was gonna throw my charger on them just to double check.

[MaximusBoatimus]

Originally Posted by shrew

Stupid question. Everything you describe sounds a lot like the batteries are simply dead. Are they holding a charge?

Checked the battery, 1 75%, other 25%, brought the one home to charge to 100%. Will check tomorrow if that's the fix. Ordered 2 new starter selonoid and 2 90amp fuses, now got spares just in case.(hopefully) Lol

[jrsick]

I agree with you and Mike that starter solenoid is likely source of problem.
Regarding your batteries; is one deep cycle and one shallow cycle (starter battery)? How are you positioning your battery switch for engine starts?
The battery with 25% is probably a goner. If it sat at 11.9v for a couple of days it is likely sulfated beyond repair and not recoverable.
It's worth a try to charge it though. Does your charger have a recovery or repair feature?

[MaximusBoatimus]

Originally Posted by jrsick

I agree with you and Mike that starter solenoid is likely source of problem.
Regarding your batteries; is one deep cycle and one shallow cycle (starter battery)? How are you positioning your battery switch for engine starts?
The battery with 25% is probably a goner. If it sat at 11.9v for a couple of days it is likely sulfated beyond repair and not recoverable.
It's worth a try to charge it though. Does your charger have a recovery or repair feature?

Optima 400 Battery Charger.

Best investment I ever made. I've used it to recover dead batteries, this one is an AGM exide. Hopefully itll get me by this year.

[MaximusBoatimus]

Both same AGM blues, no change after battery charge. Still no pwr to gauges or motor.

[MaximusBoatimus]

Apparently issue was corroded connector to the harness.

[mmwjr]

Originally Posted by MaximusBoatimus

Apparently issue was corroded connector to the harness.

That’s a common issue with the 10 pin harness connector.

[MaximusBoatimus]

Any suggestions to removing corrosion? Was gonna try the ole Vinegar bath, after with a touch of MAF cleaner, and dielectric grease sammich

[mmwjr]

I use and electrical contact cleaner (West Marine, Home depot,...) and a dielectric grease.

[shrew]

Originally Posted by mmwjr

I use and electrical contact cleaner (West Marine, Home depot,...) and a dielectric grease.

Then repeatedly plug and unplug the connectors 20+ times. It will slowly scrape corrosion and expose good metal for contact.