I have a 65, my wiring harness melted itself around the horn relay, as far as I know that is where it started. I replaced all the wires using a schematic I got off here. I obviously changed the horn relay also. I put it back together and now the alternator isn't charging. The alternator is only about 2 months old and it was charging correctly. So I changed the voltage regulator, no change. Since then I have changed the starter solenoid, ignition switch, dimmer switch and had the alternator tested(it was good). One of the things I have noticed is that on the starter solenoid, on the ignition terminal, with the key on I have 12 volts but with the engine running I have just under 10 volts. One more weird thing, if I increase the idle the volts drop slowly, till I bring it back to idle then it goes back to just under 10 volts. I'm not sure what else to look at. Any suggestions?

 

On mine, I had the connector on the thicker red wire going into the voltage regulator had a hole rubbed through the insulation. It sent the power coming out of the alternator to ground. Didn't smoke, didn't spark, just didn't charge the battery.

 

When you say you replaced "all the wires" does that include the alternator harness or just those that were burnt? Did you use OE type replacement harnesses or just cut and splice in replacement wires?

 

Cut and spliced. then checked with a ohm meter to make sure it had a good connection.

 

Do you have a schematic? Have you rung them end to end to verify they go to the correct terminal? In other words, nothing got crossed when you did the splicing.

 

IIRC there is a fusible link in the alternator output wire. Have you checked to make sure it hasn't gone open?

 

I used a schematic, and replaced one wire at a time to make sure I didn't mix them up. The wires from the alternator/solenoid/horn relay/voltage regulator are all new minus about six inches of the end(still color coded). I'm not running a disable link.

 

OK, take the following measurements and report your findings:

From the GND post on the alternator to the Neg battery terminal, what is the resistance in ohms?

From the other small alternator post with the white wire (no. 35 on the schematic) measure the resistance to the voltage regulator in ohms. (Look for the terminal with the white wire).

From the large voltage output post on the alternator with the black with yellow stripe (wire no. 37 on the schematic) measure the resistance to the Pos battery terminal in ohms.

After you have these measurements, we'll figure out where to go next.

If one of them is either open or even very high, then we'll dig in and find where it's bad.

 

Alternator ground post to neg battery is 000 ohms. White wire is 000 ohms. Thick power wire from alternator to positive terminal is also 000 ohms.

 

I figured out the 10 volt issue on the ignition side of the solenoid. I am running a DUI distributor and had it connected to that side of the solenoid, once I changed the location of the distributor power wire I now have 12 volts at the ignition side of the solenoid. But I still have a problem with the charging system. I jumpered the I terminal with a 12 volt source and it started charging, but I'm not sure why or if that will hurt things in the long run.

 

Also, the green and red wire(904) has 12 volts till I connect it to the voltage regulator then it drops to 6.5 volts. Not sure what that means either.

 

The I (ignition) terminal of the solenoid is only hot when the solenoid is engaged. It's purpose is to provide a full 12V to the coil to aid in starting.

Once the ignition switch backs off to the run position, ignition power only goes through the pink resistor wire dropping voltage to the coil down to around 9V. This was done to keep the points from burning out too quickly as they would if a full 12V was applied constantly.

So, applying 12v at this terminal will only bump up the voltage to the coil, effectively bypassing the pink resistor wire (if you still have one).

Since you have a DUI ignition, you have likely modified the wiring, so I may not be able to help you trouble shoot.

904 (green/red) goes to the start terminal of the ignition switch. It should only have 12V when you have the key all the way to start.

The short may have damaged the ignition switch and may be what's causing the voltage regulator to not work properly by continuously providing voltage.

I'm not familiar with the DUI, so this may not work:

1. Disconnect the plug at the back of the ignition switch.
2. Jumper from the battery to the + side of the coil.
3. Use a remote starter switch between the battery and the S terminal of the solenoid.

Once the truck is running, you should get 14.5 V at the battery.

 

I jumpered 12v to the coil and started the truck but still only has 12v.

 

And you disconnected the ignition switch?

 

I. Just disconnected the coil wire then ran a separate jumper from the battery.