The Stovebolt Site Forums The Shop Area The Electrical Bay Headlamp Wiring Puzzle 1946

For all you folks that like to solve puzzles here is a tough one!
This is on a 1946 Chevy.
The Hi-beam indicator burns on Brite or Dim.
Located the problem zone but not the problem. It appears to be in the headlight harness. First, I disconnected both headlight wires at the terminal strip. Turned on the lights pressed the dimmer switch, worked as it should, Bright, indicator light on, dim, light off. Reconnected the wires at the terminal strip, the problem reappeared. Disconnected Lo-beam wire at the terminal strip, turned lights on. Worked as it should, Hi-beam indicator light on/off. Indicator light works OK as long as either of the Lo-beam wires is left disconnected. Just do not have a Lo-beam on the side the wire is not connected. Noticed a very strange thing, on the side, the Lo-beam wire is left off, the headlamp bulb has a very dim glow. Both sides do this (not at the same time) however if both Lo-beam wires are left off, the bulbs do not have the glow on Lo-beam. I used an OHM meter to test the headlamp socket, no bleed through on either side. It is a brand new harness (JC Carter, ELW4046, in conjunction with turn signal EL13312) The dimmer switch checks OK as well as the new light switch. I am using new GE 6006 bulbs. The truck has plenty of ground.
I am at a loss as to where it is getting current for the dim glow. Ideas welcome.
Thanks,
Harold

Did you check for isolation between terminals on the terminal strip? Isolation between the contacts on the terminal strip and body/ inner fender. By indicator you mean the light in the dash gauge?

Can't follow your post BUT:
1. Turn signal switch has nothing to do with the headlights or dimmer.
2. The whole thing is simple. Regardless of terminal strip or not, the wiring is per below however you get there.

Dimmer has 3 terminals
One for hot wire from headlight switch (center terminal)
One for Hi beam
One for Lo beam
Does not matter which one you chose for Hi and Lo

The headlight bulb has three terminals
One for ground
One for Hi
One for Lo

The bulb grounds can be a separate wire to the body/frame or can be jumpered together as one ground to body/frame.
The Hi and Lo wires from the dimmer usually go to the left light and jumper to the right side.
The Hi wire, from the dimmer, also gets a wire spliced to it that goes to the dash bulb.

Hard to figure your problem out from afar, you will have to solve it by checking the above hook up and be SURE your grounds are straight from the bulb to the body or frame. "Plenty of ground" sounds like you are too sure. You can't blow it off like that. YOU HAVE TO BE SURE. Please keep in mind, most troubles and troubles like yours, are the ground path from the bulb to battery negative. A tortuous path indeed because it's not just a wire like the hot's are.
Also check, as said, those silly terminal blocks that should be eliminated. And check all the wiring. Check that the Headlight switch body is grounded to dash.
When it's all rechecked three times, when all grounds are ACTUALLY good, terminal blocks checked, dimmer wiring and headlight switch wiring and bulb sockets/wiring are checked...it will all work. So dig thru it all and clean it up.

beware of old/sagging/broken terminal strips, old brittle bakelite headlight bulb connectors, bad headlight switch, bad dimmer, loose crimps, mis-wire, loose screws, loose contacts, corrosion, weak battery and possible need for a relay.
Good luck and report back.

Bartamos,
1. Turn signal switch has nothing to do with the headlights or dimmer. I know this, just clarifying my system
2. The whole thing is simple. Regardless of terminal strip or not, the wiring is per below however you get there.

Dimmer has 3 terminals This I know.
One for hot wire from headlight switch (center terminal)
One for Hi beam
One for Lo beam
Does not matter which one you chose for Hi and Lo This I know also

The headlight bulb has three terminals Also known. As I said this is a brand new harness
One for ground
One for Hi
One for Lo

The bulb grounds can be a separate wire to the body/frame or can be jumpered together as one ground to body/frame. Each lamp is individual grounded to body. No rust new restoration. Grounded to bare metal.
The Hi and Lo wires from the dimmer usually go to the left light and jumper to the right side.As I stated wires are correct, new harness
The Hi wire, from the dimmer, also gets a wire spliced to it that goes to the dash bulb. This is included in the new harness.

Problem restated:
First, I disconnected both headlight wires at the terminal strip. Turned on the lights pressed the dimmer switch, Hi beam indicator lamp worked as it should, Bright, the indicator light on, dim, light off. Reconnected the wires at the terminal strip, the problem reappeared indicator lamp burns on both Hi & Lo beam. Disconnected Lo-beam wire at the terminal strip, turned lights on. Worked as it should, Hi-beam indicator light on/off. Indicator light works OK as long as either side of the Lo-beam wires is left disconnected. Noticed a very strange thing, on the side, the Lo-beam wire is left off, the headlamp bulb has a very dim glow. Both sides do this (not at the same time) however if both Lo-beam wires are left off, the bulbs do not have the glow on Lo-beam. I used an OHM meter to test the headlamp socket, no bleed through on either side. It is a brand new harness (JC Carter, ELW4046[b][/b] The dimmer switch checks OK as well as the new light switch. I am using new GE 6006 bulbs. The truck has plenty of ground.
I am at a loss as to where it is getting current for the dim glow.

GW,
Did you check for isolation between terminals on the terminal strip? Yes
Isolation between the contacts on the terminal strip and body/ inner fender. No. but I will. Had not thought about that,
By indicator you mean the light in the dash gauge? Yes, the Hi beam lamp

My post is not whether you know how it is supposed to be wired. I figured you knew. I went over it so you would CHECK it. If you just want to keep stating the trouble without troubleshooting, by checking each wire/item per my list, you will get nowhere.

Please realize that when something is wrong, then something is wrong. You have to find it. We can not actually find it because we are not there. The best advice is what I said. Go over it all. Not in your mind, but in your garage. CHECK EVERY WIRE AND CONNECTION.

What you have done with disconnecting wires and using meters is not working. You are at a loss. I am trying to help. I am telling you what I would do.
I would know that some wire or connection or ground, or the other causes I already took the time to spell out, were the reason. I would find it by carefully going over everything until I spot it or use a jumper replacement wire to test a wire/circuit. These wires are mostly under the hood. Just a few under dash. Not hard to check.

Lets don't dwell on what you know. Let's work on what you don't know. You don't know what is wrong. I did not mean to insinuate you don't know how the system works. I have to begin with the overall picture so that it may jog your thoughts about something. It may encourage you do STOP: and start checking everything. One at a time. You seem to want to assume everything is OK. It's not.

I know you have a new harness. I don't know if you just installed it or what. I don't know what other parts are new. I covered every possible cause and parts that could be the problem. I suggest you read my post with an eye towards troubleshooting and physically checking all the items I listed. You just ignored them by saying: I know, I know, I know.

The other reason for giving the details is for future members who search this problem.

Harold, I am trying to help you. I will keep trying until you say otherwise. I am tying to explain that you need to inspect the system carefully. Troubleshooting is an art. Most people look and don't see. They assume they did something correctly because they "knew"....or they have a new harness. None of that matters to the person who is a pro at troubleshooting. NOTHING IS TRUSTED. EVERYTHING IS LOOKED AT FOR MORE THAN TWO SECONDS. TEMPORARY JUMPERS ARE USED TO REPLACE WIRES. TERMINAL BOARDS ARE TEMPORARILY BYPASSED, ETC.

When you troubleshoot your own work, you have to throw away your ego. You have to say "one of these wires or connections or parts is bad and I have to find it." In this case, you can not keep stating the problem and hope that it isolates the cause. It does not. You have one of those crazy electrical problems that can be ground, bad bulb, intermittency, bad part, cold solder joint, feedback, etc etc. It can only be found by starting at the headlight switch and working towards the bulb.

Here is the part of my other post you did not quote:

When it's all rechecked three times, when all grounds are ACTUALLY good, terminal blocks checked, dimmer wiring and headlight switch wiring and bulb sockets/wiring are checked...it will all work. So dig thru it all and clean it up.

Take off Hi and Lo wires at dimmer, leave the hot wire on, turn on headlights, see that dimmer terminals show hot on each terminal as you push the dimmer switch, and that the indicator operates correctly. If all is good there, then obviously the problem is after the dimmer.

Then run temporary wires from the two dimmer terminals directly to the bulb terminals. No connectors involved. No new harness wires, no old wires. Bypass the terminal strip. You see the method here? Bypass everything and use new jumpers to isolate the problem. If you get success, you gradually put it back together until problem reappears. Bingo! you have isolated the problem. To isolate a circuit component you eliminate it/bypass it to observe any change.
It seems like a lot of work but it is THE fastest way in this case. Just get some long pieces of wire not used on the harness or what you have laying around.
The dimmer terminals and the bulb terminals may have standard 1/4" blade contacts which accept a 1/4 female crimp contact for your test wiring.

Two possibilities come to mind here. One is that the ground for the headlights is bad. Two, the wiring to the headlight socket is incorrect. With two of the headlight terminals interchanged, they will still light but not correctly.

I have to agree with truckernix, poor ground would be my first suspect.

My posts and quotes has the word ground 14 times .....and this is one more. 15

Most electrical problem are repaired by correct grounds. All you need to remember is grounds grounds grounds grounds grounds. everything needs a good ground. Not just a good ground to the body part but a ground to the battery. The body must be grounded ,the dash must be grounded,the frame must be grounded. And the power source must be grounded. Electricity will not flow until it finds away to go back home. And it will find it's way home through a dash light bulb.

I will continue my quest this Sat. Thanks for all your inputting this is what makes this a great
Forum. I will let you know what I find.
Thanks

Been following this thread, since I am at about the same same stage Harold described. Trying to understand the nomenclature. The term “isolatated” has been used several times. What does that mean?
Thanks in advance.

isolate?

"When you remove or set apart one thing from others, you isolate it."

Should have been more specific, Tim. Sorry. I am trying to make sure I understand correctly. The isolation between terminal strips should be assured, if a new strip is used. That assumes the mounting medium hasn’t been damaged. It’s the second part I am not following, “body and inner fender”. If a new strip is used the mounting plastic-like material would seem to suffice as an isolation medium?

I will tackling this task in the soon coming days as Sparky is down to a small handful of tasks remaining for “completion”.

The term isolation can also mean insulation or spaced sufficiently to prevent arcing or creep. They are talking about the phenolic being in good shape to keep the metal tabs/screws from touching each other and having proper fender dimples to keep board up off (insulated)(isolated) the inner fender. Just a warning to check everything new and old. We don't know if, for instance, the mounting of the board was over tightened or mounted wrong.

It is super crazy to use those. Totally unnecessary extra connections. They were discontinued in the years after this.

The other isolation meaning used when speaking about troubleshooting was explained already, as you know.

Bartamos,
I have bypassed everything. Jumper from the light switch to each headlight. Jumper to a remote Hi beam indicator lamp. Nothing going through terminals, connectors, harness or dimmer switch. Still get voltage to the indicator lamp from both Hi & Lo beam. Even put current directly to the headlamp (no harness), one terminal at a time and indicator lamp burns on both. Put current to Lo term and touched indicator lamp to Hi and lamp lit up. suggestions????

Sounds like you are pulling power for indicator from power to the switch, not from the high beam power.

Dennis

On my truck there is enough light from the dash lamps to show a faint illumination of the high beam dash indicator light. When you go to high beams then it actually turns on the high beam indicator dash light.

I will check. It is a faint glow
Thanks

Did you do this first?

Take off Hi and Lo wires at dimmer, leave the hot wire on, turn on headlights, see that dimmer terminals show hot on each terminal as you push the dimmer switch, and that the indicator operates correctly. If all is good there, then obviously the problem is after the dimmer.

You say that harness has a wire from the dimmer Hi output to the lamp. Are you sure about out that circuit?

It now seem like you and others think your only problem is the indicator lighting on both Hi and Lo. I thought there were bigger problems?

You say: 1) Jumper from the light switch to each headlight..... this bypasses the dimmer, therefore his bypasses the indicator lamp because the lamp is lit by the dimmer. So it can not light the indicator.

You say: 2) Jumper to a remote Hi beam indicator lamp...... Don't know if this was done at same time no 1 or not. Don't know "jumper" from where to where?...... remote lamp, like another lamp? was it grounded?

3) Even put current directly to the headlamp (no harness), one terminal at a time and indicator lamp burns on both. Put current to Lo term and touched indicator lamp to Hi and lamp lit up.
Where did this direct current come from? the battery direct? the headlight switch direct? The lamp is only connected to the Hi beam output of the dimmer, nothing else. You said the harness takes care of that. Are you trusting the harness and yourself too much?

When you say everything is disconnected but one direct test wire, the lamp can't light.

Harold, bypass one thing at a time to see if you can find a place where it all works. I may have led you to bypass everything all at once. That is not a good idea for me to say when trying to help someone. It leads to all kinds of mixups. One at a time, one step at a time to see any progress slowly is better.

GW
Pulled the bulb and grounded the socket
Same result bright for Hi beam very dim on Lo beam
Removed the bulb and checked wiring back to
dimmer switch. Truck wins this round, there is
Nothing else to check!
I do not drive it at night anyway.
Have a great weekend.

You too.

P.S. I was still adding info when you posted. Sorry. Maybe read it again or not. Electrical is sometimes hard to fix over the internet. You have made a great effort. You will fix it another day with better help.

I know you said you checked the dimmer switch with an ohm meter. If you have a volt meter make sure when you switch from high to low there is not a slight voltage on the opposite terminal. It seems like the dimmer switch would be the only voltage source to allow what you are seeing. Only other thing would be damaged insulation on wiring.

I don't think Harold wants us to think about this for awhile.