ignition switch confusion

I took the easy way and installed a 40 anp fuse and all seems well. Thanks for a good discussion of things that could be done.

Tim

I'll let ya' in on a little poorly kept secret...............There's a really good easy to follow diagram floating around out there for the mid 80's PCM engines.

It was made by some guy with the same name as you

You should get paid a royalty fee every time it gets used

Twice the fee when it shows up on Team Talk,

Three times the fee when it's used for an Indmar 351 reference

TRBenj wrote: If you want to mimic the factory set up, then you would want to upsize the wire between the alt output and main engine breaker (unprotected side) such that it can handle the full rated load of the alt. I’d have to check the chart, but this may be an 8awg or even 4awg for 105a. The main engine breaker is there to protect the other side (10awg wire feeding the dash) and shouldn’t be changed.

I've done just that with a Delco alternator, it works just fine moving the alternator feed to the upstream side of the main breaker with bigger wire instead of the dowmstream side where it was originally hooked up by PCM.

Doing it this way, 40 plus amps anywhere on the "protected" side causes a breaker trip and takes the battery and the alternator out of the picture at the same time,unlike the PCM way which takes the battery out but must depend on the alternator cooking itself if you have a fault is between the 40 amp breaker and the 20 amp breaker on the dash.

You might figure a fault there is pretty unlikely but..............sheet happens

Which naturally leads to the question of why they did it the way they did

I've also taken a different approach and left the PCM wiring as is, including the 10 gauge Orange alternator output wire and put a 40 amp fuse on the alternator output terminal with the Orange wire hooked to that.

Basically turned the higher capacity alternator into a 40 amp alternator with that fuse, but the boat has no extra loads and won't ever use 40 amps unless there's an electrical issue like a ground affecting the system.

Like Cyclone who asked the original question I got the higher amp alternator because it was cheap and easy to install And Delco parts are readily available most anywhere and they're easy to "fluff and buff"   

Both ways have given no issues    

Having read this info I'm a little worried.
I put a 1 wire AC Delso alternator in my 85 SN. It's 105 amps if I remember right. I hooked it to the orange wire and left the excitation wire unused. It seems to work great but it sounds like I could melt some wires.
I have no extra electric loads in the boat than it came with when it was built I bought the alternator because it was cheap and easy to hook up, not to supply lots of power to anything.
What can I do to protect my wiring?

Because it wasn’t stated explicitly, it should be noted that the purpose of the breaker is to protect the WIRING (breaker size should be nominally lower than the current handling capability of the smallest wire attached to it). If - and only if - the wire size has been appropriately selected to handle the full rated output of the alternator, should the breaker be similarly sized.

In this case I suspect it is... but to omit the wiring from this particular conversation seems just a tad short sighted.

good info...   so did you add one to your 76? when I ordered mine Vince ask me which one I wanted and I didnt know what to tell him. so we went with 40 since it was cheapest and the alternator didnt make but 35-37a anyway. I guess 40 is better than none

KENO wrote: TRBenj wrote: Correct that has nothing to do with the alt. Alt needs to hook to battery one way or the other. Has to go through ammeter first if that’s at the dash. Otherwise I would connect the orange wire to the protected side of the engine breaker. The solenoid is the unprotected side. The diagram shows a rather invisible engine breaker. My 76 ( with an ammeter) had the same rather invisible breaker as built by PCM Maybe he's got one , maybe he doesn't

nope didnt ever have one.   which explains a melting contest between the 10 ga red and 10 ga orange wires up to the dash at some point long ago.    I'm 42 and can always remember as a kid noticing the melted wire connector at the back of the engine. anyway all fixed now and with a breaker.

KENO wrote: hotrod5337 wrote: KENO to answer your question, everything was hooked up when I was taking the readings. which is still kind of strange to me. without the orange wire connected to solenoid I would still think that with the key ON I should still see 12.5v (same voltage on switch batt post) on switch ign post ? Like TRB said, that question had nothing to do with the alternator but was about how you checked to get the voltage on the I terminal on the switch way back in the beginning of this thread If you unhook everything from the I terminal and turn the key to ON the voltage on the B terminal on the switch and the I terminal should be the same if the switch is good.

10 4. understood. I will check this evening

hotrod5337 wrote: KENO to answer your question, everything was hooked up when I was taking the readings. which is still kind of strange to me. without the orange wire connected to solenoid I would still think that with the key ON I should still see 12.5v (same voltage on switch batt post) on switch ign post ?

Like TRB said, that question had nothing to do with the alternator but was about how you checked to get the voltage on the I terminal on the switch way back in the beginning of this thread

If you unhook everything from the I terminal and turn the key to ON the voltage on the B terminal on the switch and the I terminal should be the same if the switch is good.

KENO to answer your question, everything was hooked up when I was taking the readings. which is still kind of strange to me. without the orange wire connected to solenoid I would still think that with the key ON I should still see 12.5v (same voltage on switch batt post) on switch ign post ?

hotrod5337 wrote: i switched it to a volt meter and did away with the orange wire I will look at the dash wiring.    thank you

How did you do away with the orange wire?

It sounds like you don't have a complete circuit from the Alternator to the battery anymore.

Here's an engine diagram for a 1974 PCM that shows the wiring with an ammeter and tells how to wire for a voltmeter. See the dotted lines and the notes associated with the Orange wire. For a voltmeter the Orange wire goes straight to the starter solenoid (same terminal the battery cable hooks to) Then the mile and a half of Orange wire going up to the ammeter then the short Red wire to the keyswitch isn't needed and the battery will still charge.

It's a little tough to understand but the diagram shows how to wire it.



Also like TRB said, don't worry about that switch in the throttle control, they also got used with IO's and the switch was used in that application. With the Velvet Drives the switch on the transmission does the job.

Edit..........after seeing your last post about the switch being wired up (from the factory?) just use whichever switch you want to use.

And another also.............were the readings on the I terminal taken with nothing at all hooked to it ?

actually the trans nss was bypassed on this boat and only used the controls switch. but the controls switch was acting up and I had bypassed it years ago last time the boat was used to get back.   the boat was bought new in 74. couple pieces of interior re-covered over the years but boat is all original except for the things I've done to it. I'm not too savvy with what all components etc that correct craft used on the certain models.   I'll take a picture of it tonite .   I currently do not have it wired up. actually in process of installing new rudder and prop shaft packing along with new gland.

took me 2 hours to get the dang shaft coupler off. I'm wondering now how the hell I'm going to get it back on. had no idea it was a press fit. I guess deburring if needed and heating it?

I guess nows a good time to replace trans output shaft seal too. one thing leads to another with this project

well I guess it's not really a neutral safety but the switch inside of the Morse control. or teleflex control whoever's makes it. I've yet to see controls like the one on my boat. nuetral lock out knob has another switch in it.

I see what I did now with fusing the wrong circuit. I guess I was thinking that the breaker at the solenoid would cover the main 12v to dash wire. is it just a redundant fuse?

same thing I wondered about with having two nuetral safety switches. does one do something the other doesnt? even though with two small kids I'm all about it

Presumably the boat is a 74 like the engine...

Take a look at the dash wiring diagrams in the reference section. They’re typically for 80’s boats but the only major electrical difference would be the use of a ammeter vs voltmeter. That change happened around ‘79.

Yours looks to be wired for a voltmeter.