Ignition Switch Confusion

[adamsanders]

I have a problem I am hoping to get some advice on regarding an electrical issue I am having on my boat. It is a Baja SK200 ski boat with a Mercruiser 454. Last fall while I was winterizing the boat, I was cranking it on a low battery. I went to swap the battery but apparently I had held the key on too long because I had no power whatsoever after the new battery was hooked up. Nothing to the dash, starter, bilge pump, etc. I figured I had blown a fuse due to the low voltage /high current cranking. I jumpered the ignition coil and cranked the boat to finish winterizing. Now I am trying to track the problem down.

I have followed 12V from the battery to the starter, and back up to the BAT post on the ignition switch with the KEY OFF. When I turn the key to ON/I, the 12V disappears from both the BAT terminal and the Ignition terminal. If I take a jumper and go from the positive of the battery to “I” terminal on the ignition switch AND turn the key on, the dash lights up. I can also crank the boat if I put another jumper on the Start terminal of the switch.

My confusion comes from the fact that when I take the switch out of the boat completely, I get continuity between the battery post and the ignition post with the key on and also to the start post when turned to the correct position. This would indicate a good switch. What am I missing here? Thanks in advance.

 

[sam am I]

The switch is good!.......however, the 12V feed on the orange "B" wire is flaking/dropping out.

Chase the orange wires' 12V back to its source (the battery), probably a corroded/flaky inline fuse.

 

[adamsanders]

So even though there is voltage on the orange wire the entire time the key is off you still think it is a fuse? That’s the part that confuses me.

 

[alldodge]

So even though there is voltage on the orange wire the entire time the key is off you still think it is a fuse? That’s the part that confuses me.

If (big if) someone has not changed any of the wiring, then there should be a 20 amp fuse on the orange wire. Someone has changed part of the wire because the wire should be Red/Purple. You have a bad connection somewhere between switch and the motor (50 amp breaker) as Sam mentioned

 

[Scott Danforth]

when you changed batteries, did you clean the terminals on the batteries and cables?

 

[adamsanders]

I did not “clean the terminals” but they do look okay and I am not observing a voltage drop between the battery and the starter, circuit breaker, etc. I am surprised to hear that the wiring looks like it has been altered. Where would this 20 amp fuse normally be located?

 

[sam am I]

So even though there is voltage on the orange wire the entire time the key is off you still think it is a fuse? That’s the part that confuses me.

Yes and/or flaky connection/s.......I'll try to spare you the physics lesson here but, what is happening is when a crappy connection forms, the(a) resistance in the connection become "active" dependent on current flow/heat.

The connection resistance goes through the roof between where the two halves meet (the connection) when current is pulled through(key to "on", orange wire goes to zero volts) the connection, then when the connection has little or no current being pulled through it (key off), the "active"resistance goes way back down (orange wire goes back to 12V). Crazy stuff huh?

 

[adamsanders]

Okay I will check that. I suppose i would be looking any connection in the current path prior to the ignition switch. To me, that kind of failure would be more likely to happen over a period of time though. This was completely sudden and did not gradually come on. I’m confident it is the result of the system pulling such high current because I forced it to crank on a low voltage battery. The cable terminals were scolding hot to the touch. That’s what led me to believe it was either the switch or a fuse. The circuit breaker didn’t trip but it is 50A and someone above mentioned a 20A fuse that cannot find. I assume it would have popped first. Does anybody have a picture of this 20A fuse?

 

[alldodge]

Its normally an inline fuse, just follow the wire back and you should find it under the helm. If its not there then its been removed, or its in the fuse panel. Follow the orange to find red/purple

 

[adamsanders]

Forgive my ignorance but I have never seen a fuse panel on this boat. Everything on the dash, every switch, etc, has its own dedicated circuit breaker right there on the dash face.

 

[alldodge]

This is the reason I mentioned an inline fuse or fuse panel. On your style boat, the fuse is normally not on the helm but under it using an inline fuse

 

[adamsanders]

Okay I’ll need to probably pull a deck panel up and look then. I don’t see anything hanging up behind the dash.

 

[adamsanders]

According to the diagram above, there’s no way I would have 12V to the “B” terminal on the switch if that 20A fuse was blown, which I do as long as the key is off.

 

[sam am I]

You have an intermittent issue most likely cause by corrosion .....please read my explanation in #7.

Under a load, key "on", somewhere along the path of the orange B+ wire, it's opening up intermittently when a current demand (key "on") is put on the circuit......Could be a fuse, flaky circuit breaker, could be burn't/frayed section of wire, could be a connection, who knows.

Most folks here know and experienced that there is typically a inline fuse and are, with good cause, guessing based on this experience that it COULD be the issue as we've seen it soooooo many times here.

However, the fact remains, that B+ orange wire MUST remain 12V when the key is switched to "on" and it's NOT! This orange B+ wire goes (for all intensive purposes) directly to the battery with a fuse placed TYPICALLY somewhere inline in the path and perhaps a few connection on the way as well, a intermittent corrosion based failure is the typical suspect. Especially so with what you have described of how your failure is occurring.

If tearing up deck plates to get to things is out of the question, I'd be inclined to run a new fused B+ orange wire.

Disconnect the old B+ orange wire from the ignition switch "B" terminal, tape it and tie it off somewhere, hook up your new orange B+ feed at ig. switch "B" terminal and be done.

 

[adamsanders]

Okay, I’ve got another update and I think I’m beginning to narrow it down. I left the ignition switch completely out so I could eliminate any confusion from that. Contrary to what I had thought before, I do not have 12V on the B+ wire to the ignition switch so I began tracing backwards on the circuit. The orange B+ wire seems to run to the circuit breakers that protect each switch for the bilge pump, horn, etc (see picture). The circuit breaker panel seems to be fed by a large gauge red wire that comes into the top circuit breaker. No voltage here either. This wire runs directly into the loom and travels with the steering cable into the hull and back to the engine compartment. It has a drop of two wires to the bilge pump and then goes up to the large round plug on the engine. THERE IS 12V at this plug on the pin that connects to the aforementioned red wire. There has to be a fuse or burned wire somewhere between this plug and the dash. My bilge pump also does not work when I manually lift the float. The ONLY thing between this engine plug and the bilge pump is this grimy connector. (See picture). Any input is appreciated.

 

[sam am I]

Did you pierce through the red wires' insulation just above this (see below) somewhere to check for 12V? This looks suspect to me from here...It's a inserted spade lug jumper direct connecting the red to the orange?

 

[adamsanders]

No I did not. It looked odd to me as well. I probably need to cut the zip tie and pull those apart to see what’s going on exactly. I checked that orange spade terminal below the red and it did not have 12V on it. Is it normal for the ignition circuit to run through all the circuit breakers before going to the B+ ignition switch wire?

 

[sam am I]

Not trying to play word games here w you BUT, It's not "run through" per-se, its "tapped off".

Looks like a "daisy chain" across the top of breakers of the B+ feed. Items (bilge, lights, etc, etc) are tapped off through breakers than through switches. One tap (with a breaker/fuse?) in particular is going to the Ig's B+ feed.

And by the way, you did have 12V once on the ig. switch as you reported early on and retracted in #15, it's just intermittent and opened up probably due to corrosion in a "connector" or "fuse" or "breaker".......BUT you heard this already once or twice, right?

 

[adamsanders]

Is there any precaution I need to take when separating those harness connectors? That would allow me to more accurately tell where I’m losing continuity on that wire.

 

[alldodge]

The connectors should come apart without damage, That said if there corroded they may be damaged. If they are corroded and damage does ossur, they need to be replaced/repaired any way

I've had a 10 pin pull pines out when unplugging before, just what happens