No gauges, no start, no trim/tilt, can't find an answer

[CrazyRandy]

Hi all..I've read through a million posts about similar issues without resolution...

I have a 2003 Yamaha V150TLRB and 704 remote, perko switch, and a good battery.

Problem started with key switch fluctuations, then the relays started buzzing when I turned the key or hit the trim/tilt. Then I would turn the key, after a few second the gauges would light up, and turn the key or tilt/trim and poof, lights out, no gauges. Now, nothing at all...this all took place progressively as I describe over the course of a few days. I'm not 100% on the terminology but in the main harness, I count 8-pins, the red wire shows 12.7V (battery slightly run down) and all the other pins (even the black one) show right around 10.7V....that's where I got stumped. All fuses are good, all connections look good (that I can see)...I thought the key switch might be bad? I've seen other posts where folks seem to know what controls what and I'm going to buy a shop manual but in the meantime...can someone give me a run down of what I should be metering on the incoming harness pins, how to check the key switch (power to blue and yellow = good?)
And hopefully someone who's familiar with this issue and can point me in the right direction? I'm pretty savvy electrically, just don't know enough about this system. Thank you. Randy

[boats.net]

You should have battery voltage between red wire and black wire at key switch and battery voltage between yellow wire and black wire with key on, if no voltage or low voltage at red wire then could be bad battery, battery cables, battery switch, cable connections, ground wires on engine, fuse or main harness between engine and key switch. If no voltage at yellow wire then bad key switch.

[99yam40]

Exactly how and where are you measuring the voltage on the pins?
Did you unplug the connector and test on the motor side?
Where are you putting the negative lead of the meter while checking voltges? Directly to the negative battery terminal?

The black wire should be negative / ground. Not sure how you are reading + voltage on it unless you have bad negative connection to battery.

[CrazyRandy]

I measured the voltages on the motor side of the connection and I had the black lead connected to the negative bus on the fuse block which, at the time, was jumped directly to the negative side of the battery. (for testing purposes)

[99yam40]

Sounds like bad battery or connections.
Monitor battery voltage at battery when hitting switch to see if voltage drops, if it does it is a bad battery.
If it does not start working your way up the cables and connections to see where you start loosing the voltage.

[CrazyRandy]

The battery tests fine using other 12v accessories to measure drop. I have nothing with the key switch to induce a voltage drop..I'm going to check power to the yellow wire...even if the battery were bad, I'd at least be able to get gauges wouldn't I? It holds a charge just fine. Ugh, it's just so frustrating having to learn as I go...better now than in the water!!!

[jb123]

bypass perko