The Stovebolt Site Forums The Shop Area The Electrical Bay Another Dim Headlight Problem

Hello All,

It's been some time since I have posted but dealing with an issue and wanted some advice / direction. I searched the forum on this topic and there are a lot of different answers which mostly revert back to bad grounds. Let me share what is going on with my truck.

I purchased this truck and picked it up the day after Memorial Day and have not driven after dark until last weekend and even on bright, the headlights are so dim that I cannot see to drive it, especially when meeting someone. Even the park lights are very dim, however the tail lights and license plate light are fairly bright.

My truck, a 1954 five window 3100 Chevy has been completely restored and is still 6 volt. The inner fenders have been repainted and new terminal blocks added. I did remove the terminals and scraped the paint down to metal where the attaching bolt grounds against the inner fender.

It has all new headlight buckets and light bulbs along with new sockets. I recently replaced the positive battery cable with a larger one (2 gauge), because at some point it had a 12V cable which is too small. I also installed a new metal ground strap between the bell hosing and frame rail.

The truck has a new 6V generator and regulator. I removed the left headlight ground wire from the terminal block, attached a heavy wire and grounded it directly to a good ground but the left headlight did not get any brighter.

I then removed the wires from the dimmer switch and connected them to a new dimmer that I have had for several years (still in the box), but no brighter. The headlight switch is still original and I am wondering if there could be some resistance with the switch.

So, I would like to wire the headlights around the switch (direct), to see if they brighten up but I am not sure which wires to remove from the switch and connect. Anyone have any thoughts on this issue?

Thank you in advance!

Kevin

It's not necessary to disconnect any wires unless you just want to simplify things somewhat. Connect a heavy wire (#12 or #10) to the battery terminal at the starter switch, one long enough to reach the headlight terminal blocks. Touch the wire to each connector for high and low beam (stay away from the ground with the hot wire!) If the lights brighten up noticeably, I'd suggest installing relays that take the power directly from a battery source like that starter terminal, and use the wiring from the dimmer switch to power the relays. You'll need two 6 volt 30 amp relays, one for high beam and another for low, but they're very inexpensive, and Ebay has hundreds of them. Mount the relays on the radiator support close to the headlight terminal strips.
Jerry

My headlight switch was old and getting difficult to move. When I replaced it with a new one, it made a big difference in the headlights. I don't know how your ground terminal is connected but I installed a short ground from the terminal to the fender. I grounded the passenger headlight separately on that side.

Thanks Jerry (Hotrod Lincoln) ! And truckernix!

Kevin, X2 on Jerry's advice. This links to my 6 volt headlight upgrade with relays post. The difference is night and day (I know, terrible pun).

Relays I used. I did buy a spare that now lives in the glove box since along with the two headlight relays I have one on the heater blower motor. As you'll likely learn, you can't just drop by Napa or any other parts store and buy 6v stuff anymore.

Good Luck, Ron

Ok Jerry, "Hotrod Lincoln".

Today when we got home from church, I went on to experiment with the 54's dim headlights as per the advice. Since the key switch is a little hard to get to, I just removed the retainer ring that holds it in place and pulled it out of the dash and allowed it to hang down where I could get to the battery terminal.

I had a piece of 10g but it wasn't long enough so I used some 12g that I had. Ran it into the firewall and put a connector in it and attached it to the batt terminal. I them touched it to the bright terminal on the term block and the lights do possibly seem a little brighter but not for sure since it's not dark.

Anyway, I removed the 12g wire, tightened up the screw on the battery terminal and put the key switch back into the dash. I started the pickup and the amp hand is on the left side of center. I pulled the headlight switch out and on bright, it pulls the amp hand further to the left side of center.

Kick the lights on dim, and it dims the dash lights and pulls the amp hand all the way over to the left. Not sure what is happening. Almost acts like a direct short. Before today, I have not had this issue and the amp hand is always on the charge side.

Any thoughts on what may be going on?

Thanks!!

Kevin

You've got a short somewhere, probably from tinkering with the wire harness under the dash. What were you doing under there? I suggested running your hot wire from the battery cable connector at the starter, where it's easy to reach. Now you're going to need to do some wire tracing and find where the short is. Try tracing the wire from the ammeter to the light switch, the headlight switch connections, and possibly the dimmer itself.
Jerry

Well, I know where I messed up then! For some reason I had ignition switch on my mind when you said starter switch and Instead of coming off the starter switch on the starter, I went from the batter terminal on the ignition switch and out to the headlight terminal. I must be totally absent minded today. I hope I didn't cause myself too much of an issue.

Sometimes the more I feel I have learned from these old trucks, I find out how much I don't know.

It happens all the time to many of us, kthomas.

Keep asking questions and posing problems.

Ok, now that everyone including myself knows how stupid I am, the problem was that the speedo cable had gotten against one of the terminals on the dimmer switch. Thank you Hotrod Lincoln for pointing me in the right direction, The dimmer switch is the first place I looked and found the issue.

Well, the lights are no brighter going straight from the starter switch to the headlight terminal so there must be other issues.

Bad ground from rust or new paint? The ground for the headlight has to pass from the back of the bulb, through the pigtail, through the inner fender, through the cab, through the frame, to the negative post of the battery.
You can test the ground to headlight with a long wire like you did with the hot wire.

What's the number on your headlight bulbs? It's possible someone put 12v bulbs in before you bought the truck. If that's the case they'll never get bright on 6 volts. Pull a bulb and give us the number on the back.

It would take me several pages to list the dumb-donkey stunts I've pulled since I started getting paid to fix things in 1958- - - -it's all part of the learning curve, and the embarrassing and/or expensive ones really imprint their lessons effectively. Since the lights brighten up with voltage going directly to them, start looking for a loss of voltage from one part of the circuit to another, I like to use a voltmeter with a LONG ground lead attached right to the battery's grounded post and start measuring voltages everywhere I can along the circuit. You're going to find that somewhere along the way the voltage will take an unusually big dip, like maybe from the supply wire for the light switch to the terminal that sends voltage to the dimmer switch, for instance. That would indicate a high-resistance (dirty) connection inside the switch, and/or a loose, dirty connection at one of the terminals. Another dead giveaway of a problem is a switch, a wire, or a connection that is warm to the touch- - - - -resistance generates heat. Obviously, all these tests need to be made with the lights turned on. Nothing measureable voltage-wise happens in a circuit when current isn't flowing. Good luck!
Jerry

The part number for a standard 6V 7" round headlight is 6006. A 12V the same size and shape is a 6014. Better check to be sure you've got the right voltage bulbs in there!
Jerry

If you indeed have 12 volt bulbs in there, you need to confess your sins in The Greasy Spoon.
There is a thread going on in there right now just for that purpose. It will set you free.

Hi,

when checking the number on the bulb also have a look at the glass part of the bulb. I have one in my garage, that is still working, but the glass cylinder (halogen type bulb) is all black from the inside. You can see the filament glow, but all power of the light is lost at the inside. Changing bulbs made a lot of difference.

Helmut

Hello fellow bolters!

Well, since so many of you were kind and sent replies, I thought I'd better get back to everyone with what I found wrong. Ok confessing myself here as someone mentioned, at some point (probably when the truck was restored), they put 12V headlight bulbs, and 12V park light bulbs (1157) in the truck. No wonder everything on front was so DIM!

I have to admit that sometimes the simplest things are overlooked until last but I guess I just couldn't believe that someone would actually put 12V bulbs in a 6V system. I should have looked there first!

On the positive side, I now have very bright headlights and park lights!

Again, Thanks everyone!!

Kevin

Awesome find! And it only took you 10 days to fess up. Very commendable.
I usually hold it in longer than that, but cannot keep it in forever. As I have said before, the truth will set you free (and educate others as well).
Carl

There's a thread going in the Greasy Spoon about moments we've had. Join us, we've all been there.

Carl,

You have gave me a chuckle! Thank you!! I needed that after this silly adventure I have been on!!

Kevin

Ok Tiny!

Thanks my friend!!

Kevin