The Stovebolt Site Forums The Shop Area The Electrical Bay Brake light, tail light, horn electrical issue.

So a little backstory first. I barely drove the truck when I first purchased it, I had not verified if all the lights worked properly prior. The truck is a completely restored to original version with what seems to be all new parts.
When I removed wiring from components in the engine compartment, and on the right fender, I did label the wires. I had already hooked the battery up before I was ready to install the horn. In advertently, the two horn wires touched and created a spark. I proceeded to wire those onto the horn, not thinking anything about it. Now I have realized I have electrical issues and wondering if that was the cause.
My horn does not work. My ammeter gauge goes to full charge when it’s running. Fuel gauge works properly. The running lights work properly when pulled out to the first notch. But when I pull the light switch out fully the headlights come on and the tail lights go out. Also, I do not have brake lights. If I should have gauge cluster light, I do not have that either. I do have a manual on the truck with a wiring diagram. I do see there is a fuse in the system on the diagram. But I’m not exactly sure where that is located. Unless the picture that I’ve enclosed is a picture of a fuse link type wire. The one end of that wire shown does hook to the horn wire that goes into the column. I will try to do some voltage and ohm test on wiring this weekend, but was hoping someone could lead me to what could’ve happened when I sparked those wires. that connector on the wire in the picture is a twist lock type connection, I did pull it apart, but I don’t know what it should look like if it is a fuse link blown or not. If I need to replace that link, what amp of in-line fuse should I go with? Do you think I will have permanent damage to the ammeter ,lighting switch , brake switch, etc. that needs replaced.

So when you say restored to original version. Lets get a update on make model and year of your truck. Since you don't know the condition of what it was when you purchased the truck. I would just start at battery and work your way thru the wiring.

Based on my name in the group , I was hoping it was a given that I have a 1946. It is a half ton.
Yes, starting at the battery is the preferred option. I was just hoping somebody might’ve had a been there done that instance that they could give me a little more of a clue in my search for answers.

Depending on those wires that caused the arcing, I doubt that it alone caused any problem. I don't have a wiring diagram for your truck but I assume the horn circuit has a relay on the firewall, the horn button should pull the relay in and the relay carries the heavy current for the actual horn. Lighting should be pretty simple, the headlight switch having 2 positions, 1st position should be parking/running lights fore and aft, second position should be headlights and rear running lights. The wiring at the headlight switch may be on the wrong terminals. The only fuse in my 1957 is incorporated in the headlight switch, it only handles the gauge lights and dome light. A fuse block was optional equipment on my truck, maybe yours also. Brake lights do not run through the headlight switch, you should find a brake light switch that is actuated by the peddle arm, one wire in and one wire out of that switch, one of them should be hot all the time, the switch just disconnects or connects those 2 wires.

Thanks for the info 78buckshot. I’ll do some further checking.

1. Can you confirm that when you drove it that all lights and horn and gauges were working? Before you started messing with wires?
2. I would not assume any of the wiring is correct or all is original.
3. We will not be able to answer your question as to if you did or did not cause anything. Does not matter.
4. This must be handled one step at a time. Sort of, one issue/circuit at a time.
5. The diagnosis will be suggested by asking you questions and having you do tests, one step at a time. You will not need to ohm anything. Just need an ice pic volt tester.
Firing off guesses is not how to troubleshoot,
Assume it is 6V and no non stock electrical stuff.

"When I removed wiring from components in the engine compartment, and on the right fender, I did label the wires." What were you actually doing? and why?
You should NEVER play with wiring without taking negative cable off of battery.

In 46 there is only one fuse and that is built-in to the headlight switch. Looks like headlights and park lights wires run toward the left front, spliced to right side. Left continues to a terminal block for light servicing. Right side wires go to same type terminal block for service.

In general you will just examine where there is 6V and where there is not. Operating switches off/on as you test, Let us knoe where voltage is and where it is not so we can think on it. Don't do anything else for now. Don't change anything. Likely you have several issues at once. 46 is a very simple wiring diagram. Few wires. We will be able to help you all the way if you wish.

You may eventually find old broken wires and terminations, PO mis wires, bad switches, bad bulbs, and GROUNDING ISSUES. The whole truck is the ground return path for everything and all those ground connections are 79 years old.

It seems you said you touched the two horn wires together before hooking them to the horn. One of them is a hot wire and the other gets grounded by horn button. So there would be no spark. You may have touched the hot wire to a ground or the horn body.
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bartamos,
I cannot confirm that those items worked prior. I bought the truck with a motor needing attention and I swapped it out for 261. all engine related wires were hooked up prior to the battery, except the last item horn installation. when I was retrieving those wires that were tucked in by the inner fender, I suppose one of them could have touched the inner fender instead of each other.
Looking at the extreme quality build of this restoration I was assuming everything was correct. Every wire, every terminal, every component looks like brand new. Yes I know what it means to assume. Most of if not all wires have number labeling on them so I’m guessing they used a chart and or knew what they were doing.
Going forward, I will try to verify all connections, wire routing on components etc.

As an example of troubleshooting with a volt tester. The brake light not working. The brake switch is a normally closed switch. It is held open by the brake pedal arm. It has two terminals. Use an ice pick volt tester for all these tests. It is one handed and no trying to read a meter. The is no reason to "measure " the voltage or amps or ohms. Attach the alligator clip to a good clean chassis ground spot. Then touch the pick to each of the two switch terminals. One should light the tester showing you have voltage and the other should not. If that is the case, prop or hold brake arm in the braking position. Both terminals should show voltage. If that is the case move to rear tail light. Take off lens and remove bulb. With brake still held on, attach alligator to good ground and touch the terminal down inside socket. Should show voltage. If that is the case, take bulb to bench and test it with a household 9V battery. You may see a broken filament before that. Report any test failure to us before doing anything. Your doing this little test will help all of us learn to do testing. So appreciate if you follow the procedure and report. We will discuss the remedy/further tests at that time. Just as an exercise.

I don't know what tail lights your truck ended up with. One light on driver side, light on both sides, single or double filament bulbs..... So locate the brake bulb filament socket terminal for this test.

We can do the horn after the brake lights if you wish....then down the list. One step at a time.
I don't know what the blue thing or the silver thing is. Maybe an inline fuse but doesn't seem so, maybe fusible link. But a fusible like is poor selection for those wires and would not be original. I'm thinking just connectors/crimp splice. Don't know. If no fuse inside, not a fuse holder. A fusible link is just a piece of "special" wire but not usually spliced in the middle of nowhere.

Thanks for continuing input bartamos. I did pickup a volt tester and I follow up on some checks later. I did not see a fuse or even how one would be attached to the light switch. I did see what it should look like in the manual tho. The silver barrel seems like just a connector, I found another one going to the rear lights, I do both tail lights, I will update when I can.

Must have a replacement light switch. No big.