The Stovebolt Site Forums The Shop Area The Electrical Bay Help! 12v conversion w/someone else's wiring job.

I'm working on a 12V conversion on my '53 3100. I've replaced all the parts...generator, starter, battery, voltage reg, coil, bulbs. I also had to pull the insturment cluster to install a new 60lb oil pressure gauge. When I did, I noticed that there was only 1 fat red wire going to the amp meter. As far as I can remember, the amp meter worked, but I seem to remember that the power flowed through the amp meter before it even went to the ignition switch. Is that thae case? If not, where is the other wire supposed to go?

I'm not looking forward to figuring out someone else's wiring mess.

Chris

Hy Barsteel, as you said one side of the ammeter is connected to the battery positive terminal, the other terminal has one wire which is spliced in the harness to the ignition switch, the headlight switch, and the Bat terminal of the voltage regulator. You said you have replaced the starter, are you aware that the six volt and twelve volt starters have different pitches of starter drive gears, so you need to use the flywheel which goes with the starter. You can safely use a six volt starter on a twelve volt system, as long as your engine starts quickly, so you must maintain the engine in a good state of tune, to prevent overheating the starter, hope that helps.

Here's how I wired the ammeter in my '54 3100 converted to 12v.

Lonnie -

Thanks for the schematic. My truck does NOT have a horn, nor do I think the PO even left a provision for one, so partially explains what I'm missing.

3B - Yes, I'm aware of the difference. I'm using a starter from the filling station that uses the original stomp starter setup, but it's been converted to 12V.

I'm a bit concerned with the wiring because the truck ran and started, but there's no wire coming off the amp gauge going to the starter, so I have no idea how they set up it, and I really don't relish tearing things apart to find out, but I might have to if I want a working amp meter.

Why can't people just do things right the first time?

Chris

There is no way for an ammeter to work on only one wire. The current has to flow through it to make the needle deflect. Does the truck have an alternator? If so, it's possible someone has run a wire directly from the alternator to the battery cable terminal at the starter, bypassing the ammeter.
Jerry

Jerry - The truck does not have an alternator.

It's clear that someone bypassed the ammeter, but I'm going to have to figure out what they actually did, because I want to put it right.

As it is now, there's one lead connected to the starter where the pos cable attaches, that lead appears to go right to the ingition switch. There's another terminal on the starter, but there's nothing connected to it, and I don't know what it's for.

I'm NOT an expert at wiring, nor do I have a lot of experience, so I'm just trying to figure my way through this.

I downloaded a schematic of the electrical system from the old car manual project, but it's illegible.

Chris

Here's the way it's supposed to be wired. This diagram includes the internal wiring of the regulator, but it also shows the relationship of the ammeter to the regulator and the battery.

[img]http://www.hunt101.com/data/500/D-R_Regulator_001.jpg[/img]

The terminal at the back of the ammeter opposite the one going to the battery is supposed to be the junction block for wiring to the light switch, the ignition switch, and the power to a fuse block, if the truck has accessories such as a radio or heater. The wire from the ammeter to the battery should have NO OTHER CIRCUITS attached to it, because any draw from that side will not be reflected by deflection of the ammeter needle.

I'll look around and see if I've got a more complete wiring diagram that applies to your truck, but the one shown above will get you started.
Jerry

Jerry - You're right again!

I did not run the horn though my ammeter because I read somewhere (dunno where) that the high current draw could damage the ammeter.

The '54 wiring diagram has the battery terminal of the horn relay connected to the battery terminal of the voltage regulator. It goes though the ammeter. I guess my hook up is not correct.

It will work either way, since the horn is an intermittent-use item. Anything that draws constant current like a heater fan motor, radio, wipers, etc., needs to go to the downstream side of the ammeter so the true charge current to the battery can be monitored. The generator or alternator will supply all the constant loads first, such as ignition, lights, heat, etc., and whatever is left over goes to the battery to recharge it. If the load exceeds the capacity of the charging system, the battery makes up the difference, and you'll see the ammeter go to "discharge". Plug in the cigarette lighter if you've got one, and watch the ammeter take a dive momentarily until the generator can catch up!
Jerry

Ok, the nighmare continues, but I’m making progress. I have:

A thick red wire going from the pos terminal on the starter to the ignition switch. On the ignition switch, that wire shares the terminal with another thick red wire that goes to the Bat terminal on the voltage regulator. That thick red wire is spliced (inside the harness, with electrical tape), to another thick red wire that goes to what is probably the horn relay.

There’s another thick red wire that’s attached to the Bat terminal on the light switch, which goes to one side of the ammeter. There’s nothing on the other side of the ammeter.

The light switch itself appears to be powered by a thinner red wire with an in-line 30 amp fuse that’s spliced into an orange wire that’s in the main harness, and the orange wire attaches to a 2 terminal fuse block mounted on the firewall. The other terminal on the fuse block has a purple wire attached to it that goes from the light switch, through the fuse, to the tail lights.

It appears that the entire light switch is powered by the splice with the orange wire, but I have no idea where that orange wire goes, or where it comes from.

I want to get this set up correctly, but I don’t want to do something stupid that would smoke the whole wiring harness.

Any thoughs on the orange wire, or how exactly the light switch is getting power, or anything else for that matter?

Thanks…

Chris

Hy Barsteel, as I said in my first post in this thread, the factory harness splices the one 10ga. red wire which is on one side of the ammeter into three wires, one goes to power the ignition switch, one goes to the light switch, and one goes to the "Bat" terminal of the voltage regulator. The two fuse block you speak of fused the stop light circuit, and the tail light circuit. The stop light circuit used an orange wire, one side of that fuse got its power from the stop terminal on the light switch. I think what you need to do is trace the 10ga. wire that is attached to the large terminal on the starter, find where it goes, and if possible re-locate it to the vacant terminal on the ammeter. Let us know where that wire goes now and we'll advise you how to repair the circuits, hope this helps.

3B -

The red wire from the starter goes to a terminal on the ignition switch, where it shares a terminal with a thick red wire that goes directly to the voltage regulator.

I think what I have to do is relocate the wires as follows:

1) Thick red wire from the starter terminal to the right terminal of the ammeter (looking at it from the front), and on the left terminal, have 3 - 10ga leads, one going to the bat terminal on the light switch, one to the bat terminal on the voltage regulator, and one back to the ignition switch.

PLEASE tell me if I'm wrong, although I don't think that I am based on what I've read here and schematic posted earlier.

Chris

That's a very good beginning, and the only other connection you might need to make would be to power a fuse block for operating accessories- - - -radio, electric wipers if you choose to convert, cigarette lighter/power jack, etc. If the ignition switch has an "accessory" terminal, the fuse block circuit could originate from the switch instead of the ammeter. Good luck!
Jerry

Hy Barsteel, yes it sounds like you know what you have to do with the ammeter wiring. I'm not sure where the jumper wire on the orange brake light wire is going, so you had better figure out what that is powering, as it is probably hot all the time, hope that helps

If it would help, I have the whole truck diagram for a '50. I think it is pretty much the same. It is a ".pdf" file so it should be ok to read. If you want it, drop me a line.

maytags(at)nc.rr.com

best wishes,

Les

Les, sure send it to me. Thanks for your help.

Chris

[email protected]