The Stovebolt Site Forums The Shop Area The Electrical Bay Amp gauge

I have a new guage but it doesn't move from center. I have a wire from the B terminal of the regulator and another wire from the horn terminal on the fuse block. What have I done wrong? Thanks.

I could help better if I knew what your vehicle is. Generally there is a wire from the starter solonoid where the battery cable connects to the ammeter. On some applications the horn feeds off from there.

It's a 49 3100 with a 54 235, I use a key, not the foot pedal to start it.

One side of your ammeter needs to be connected to the battery. The other side needs to be connected to the electrical system users and supplier (gen/alt). All the ammeter does is measure current to and from the battery.

The wiring diagram for 1948-49 in the shop manual reprint shows the connections you have are correct however there should be one more. The wire from the battery terminal of the solonoid should go to the same terminal as the horn wire (the + terminal).

Michelle,
what fuse block are you refering to ? The original wiring had a fuse for the tail light and a fuse for the stop light. If it is connected to one of those than no, that is not correct.

You say its a new gauge? If you didn't have an ammeter before, you cannot just wire your new one between the battery and the load. The existing wires must be cut so all current runs thru the ammeter. It sounds like you have it wired between the horn relay and the regulator. Does the ammeter move when you sound the horn? (again, you would have had to disconnect the existing wire between the two).

truckernix, the '48-49 has a different fuse block and is wired different than your '51.

Cletis,
I forgot about that. But does it sound like it is connected correctly, to you ?

As to my above post: This wiring configuration is correct if the truck is still wired per factory specs. Gord brought up a good point though. If this ammetter is an add-on replacing the one in the dash, the in-dash one must be taken out of the circuit.

Cletis,
my apologies to you. I didn't read your previous post properly.

Before I go out and start switching wires around let me describe my set up currently. I put in a new oringinal gauge cluster, not an aftermarket, the old one never worked. Right now, I have two wires from the starter solenoid going to the aftermarket ignition. Should the wire on the solenoid thats on the same post as the battery cable go to the + side of the ammeter instead of the ignition? Thanks for your help!

At the solenoid terminal where the +ve battery cable connects to, you should have a heavy gauge wire that goes to the +ve side of the ammeter. The other wire should go to the solenoid connection of your ignition switch.

Yes.

I suggest that the first thing that you do is make a diagram of what you have. It sounds like the wiring on this truck has been modified from the original (based on the fact that it has electronic ignition and you use a key to start it) The diagram can be very helpful if something goes wrong and you have to retrace your steps. Also, I find that making a drawing helps me understand what going on.

You don't have to draw everything - concentrate on the ignition and charging circuits. Draw the wires between the starter, ignition switch, electronic ignition, regulator, main feed to the lighting switch (connections at the end closest the firewall) and the horn relay. Record the color of each wire.

The other posters are correct in that there should only be one wire (a nice fat 10 gauge) from the bat terminal on the starter to the + on the ammeter. The other post on the ammeter should connect to the bat post on the ignition switch, lighting switch and the B terminal on the regulator. In my case, there are only two wires on the - side of the ammeter; one to the lighting switch and one to the ignition switch. There is a strip with three terminals on the back of the lighting switch so the horn relay B and regulator B wire connect there (works the same as connecting them all to the ammeter)

The wiring on these old trucks can vary greatly as previous owners have made upgrades and repairs. Another good reason to make a diagram and take stock of what you have first.

I was finally able to get back out to the truck but still couldn't get the ammeter to work, more advice please!

When I moved the wire that runs from the bat term on the solenoid to the ammeter (charge) instead of the ignition switch the truck wouldn't start.

Here is a description of the wires from the generator, starter solenoid and ammeter.

The 2 wires from the generator terminals go to the F & A terminals on the regulator.

The wire from the battery terminal on the starter solenoid goes to the bat term on the ignition switch and the other wire on the solenoid is going to the center post (hot?) on the ignition switch.

The charge side of the ammeter is connected to the B term on the regulator and the Discharge side is connected to the horn term on the fuse block.

Should I leave the wiring as it is and add a wire between the + ammeter post and the bat term on the ignition switch?

Or should I leave the current wiring and run a second wire from the bat post on the starter solenoid to the + ammeter.

Or should I make other changes?

Thanks for hanging in there with me.

Sounds like you almost had it. The fact that truck didn't start makes sense. Move the wire that goes from the ammeter to the horn to the same terminal on the ammeter as the wire that goes to the B terminal on the regulator. Run a new wire from the same terminal to the B terminal on your ignition switch.

The wire that used to connect to the B terminal on the ignition switch (from the starter) now connects to the ammeter where the horn wire used to be; it should now be the only wire on that terminal.

In summary: one terminal on the ammeter should have only 1 wire connected to it - this wire connects to the starter. The other terminal on the ammeter should have three wires; the new wire to the B terminal on the ignition switch, the wire to the B terminal on the regulator and the wire to the "horn" terminal on the fuse box.

Before starting the engine, turn on your headlamps. If the ammeter reads backwards (shows charge when it should be discharging) just reverse the wires on the ammeter terminals. The ammeter may not move at all as I suspect that the lights may still be bypassing it.

Remember to disconnect the battery before you start moving the wires around.

Well, I rewired it like you said, great directions- thanks! The truck starts but the ammeter is still not working so I guess I need to bench test the gauge and see if I fried it somewhere along the way. Can you tell me how to see if the gauge is still good? Again, thanks for the help!

This mite help:

Wiring In an Ammeter

I don't think that you have fried the ammeter. If you had, it would probably be "open" so no current would flow through it and the truck would not start.

Did you try the headlight test? That is watching the gauge while turning the headlights off and on? If the guage doesn't move, you can disconnect the three wires from the load terminal on the ammeter. Turn the headlights on; if they still light up then the wiring for them is bypassing the ammeter. If the headlights don't work, run a wire from the load terminal on the ammeter to the headlight switch. (one of the two terminals at the back of the switch with fat wires attached) Try the lights again - if the lights now come on and the ammeter doesn't move, then your ammeter is probably toast.