So rewiring the '28 Model A hotrod my ex father in law gave my 18yr old son a couple years ago. The wiring was a mess so I just ripped it all out and starting over with a painless wiring kit. Yeah it has more then I need, but I wanted the labeled wiring. Because the dash is really narrow I opted to install a 4 switch switch panel with 1 momentary switch for the starter. My plan/hope was to have 1 switch control the ignition (run on standard key switch) and the accessories (fuel pump, cooling fan, turn, coil, 1 switch to turn headlights/turn signals and the last switch will control high beam only. Can't seem to get my head around is how to wire that 1st switch to do what I want yet. Only the start function of the column key works and the boy wants a button for the starter anyways. With my 10SI alternator I'm running the output to starter. I have a buss bar that I'm going to connect directly to the battery (6 or 8g wire as battery is behind seats so less then 6' from battery to buss bar) with a fuse (or circuit breaker) to power the fuse block and anything I need to power with a relay. I don't like how painless has the alt regulator line connected to the alt output at the midi fuse (no real overvolt protection in my eyes) so I was going to connect that wire to a post on my buss bar. I think that will give me decent charge voltage signal. In my head if I put the midi fuse between the starter and battery that will protect the battery from a short to ground on starter wire. With the volt sense wire on the buss bar the alt should still produce safe voltage correct? How do I protect from over voltage or is that not really a problem?
The 10SI alternator works if you just connect the sense wire to the output wire, but you could run it to the bus if you really want to. I can't imagine why you want individual switches instead of using an ignition switch with a key...but hey, some guys have weird ways of doing things.
To operate a push button start you'll want to take power from the ignition post on the key and run it through the switch to the starter. You could go crazy trying to protect some wires with a fuse at each end. Chris
The boy wanted individual switches and at some point be plans to replace the steering column with one that only has blinkers it so I figured I might as well wire it that way now. I myself don't mind the switches. I know the 10SI will work with the sense wire on the output, but I was thinking it would put out more appropriate voltage if it was away from the output. I know going to the horn circuit is/was pretty common.
I don't want crazy, just safe and reliable w/o making it difficult. I have a tendency to go overboard on things.
I suggest getting a normal ignition switch, and using it, and ignore the ignition switch on the column. But to wire the individual switches, it would help if you'd remind us what wires are in the harness connection for the switch. I'd guess you have a red wire from the battery, purple for the starter solenoid, pink for ignition and gauges, and brown for accessory stuff. If so, just connect a toggle switch from red to pink and brown to turn everything on (separate switches if you want a separate ACC position), and a momentary switch from red to purple to crank the engine. Normally there isn't a fuse in the crank circuit.
You need to decide if you want the starter switch to work with the ingition off. If that's the case, connect the B+ from the ignition switch to the starter switch. If you want it to work only when the ignition is on, connect the IGN or ACC power from the ignition switch to the starter switch.
Connecting the alternator voltage sense circuit to the busbar will give it a more accurate reading than jumping to the alternator output terminal. This is why the OEM had terminals for external wiring on their alternators rather than simply doing it internally. No need to fuse the battery to starter cable. The OEs don't this; it would need to be a large fuse and you'd want to put it as close to the battery as possible, which makes the cabling a PITA. Fuses aren't to save the battery; they're to protect the wiring. For the momentary "start" button, you simply need to run power to it from a switched circuit (ie: the "ON" circuit coming out of the key switch), then a circuit from the button to the starter solenoid. You will need to determine which terminal corresponds to that "ON" circuit. It sounds like right now you've only found the "START" terminal. You'd also use that same "ON" circuit to power your other devices and control relays for the high current ones (such as the cooling fan). You will need to be cognizant of the current rating of the switch and the current draw of the components. You may need more than one relay.
The color coding is as you mentioned. That's what I though but for some reason it feels like I'm missing something. Probably ly just me thinking it's more complicated then it really is. Thanks squirrel.
That's the reason I thought putting the sense wire on the buss bar was my best bet. It's where all the load will come from. A fuse at the battery would protect the battery, but yes I do agree that a fuses primary purpose is to protect the wiring. If I remember correctly the switches are rated for 25A, but I plan to try and keep it to 20A. I'm sure 25 would be fine but in everything I've ever done I try to build in my own safety margin. Just because. Appreciate all the help guys. The wiring was a basket case when my son got it from my ex father in law (all of the non used wires were just coiled up under the heat resistant padding and not capped off. Just to get from the toggle switch to the fan the guy had 3 different pieces of wire and each end was just twisted together and wrapped in electrical tape. I gutted it w/o even mapping it out because not a single circuit matched the fuse box he used. No way I'd let the boy drive it.
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