Right light dim Left light ok '53 2R11 Commander Motor

Right light dim Left light ok '53 2R11 Commander Motor

Rob Lund
Rob Lund

March 17th, 2012, 6:05 pm #1

The above occurs no matter whether it is the high beam and low beam. I measured the voltage at the right terminal block and it is 3-4 volts. At the left terminal block there is 7+ volts. I switched the right to the left side and and it works fine, so the sealed beams are good. I cleaned all connections at the plug, disconnected all the connections at both terminal blocks and cleaned and reconnected. I jumpered across from the terminal block on the left side to the right side, same problem. I took the dimmer switch out and wired around it and there is still the same problem. My only guess now is if the actual plug at the light but that doesn't make sense because of the lower voltage. Any other ideas would be appreciated.

Thanks for your time.

Rob Lund
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Skip Lackie
Skip Lackie

March 17th, 2012, 8:47 pm #2

If the bucket itself is not well grounded to the fender, you could get the symptoms you describe. I believe the ground post of the sealed beam is just grounded to the headlight bucket.
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Rob Lund
Rob Lund

March 17th, 2012, 8:58 pm #3

I measured the voltage from the ground screw that the wire that the headlight ground wire was attached to. I sraped the paint at the screw, wire brushed the screw. I there way to check that? Maybe just a new wire to verify?
Rob
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Lee W.
Lee W.

March 17th, 2012, 9:49 pm #4

If the bucket itself is not well grounded to the fender, you could get the symptoms you describe. I believe the ground post of the sealed beam is just grounded to the headlight bucket.
I'm in the process of preparing my '59 Scotsman to make it roadworthy and my experience with the lighting is that it can be one or a combination of three things; a burned out bulb, a bad ground; or bad connection. I found that both my headlight buckets were not grounded to the body because of rusty mounting screws. The headlight socket has 3 wires going to it. One wire should be connected to the bucket itself for a ground. The other two wires provide current for your low and high beams. With the bucket mounted on the truck you can check for resistance between the grounded terminal of the socket and the frame.
Lee
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Skip Lackie
Skip Lackie

March 17th, 2012, 11:06 pm #5

If the bucket itself is not well grounded to the fender, you could get the symptoms you describe. I believe the ground post of the sealed beam is just grounded to the headlight bucket.
I think Lee answered your question, but yeah, I would run a new wire from where the headlight ground wire screws into the headlight bucket to something really solid, like a generator-mounting bolt. I had to do that with some directional signals that were not making electrical contact through the fenders to ground.
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John Weinrich
John Weinrich

March 17th, 2012, 11:18 pm #6

If the bucket itself is not well grounded to the fender, you could get the symptoms you describe. I believe the ground post of the sealed beam is just grounded to the headlight bucket.
ran ground wires from everything to a terminal block I mounted on the inner fender and then ran a couple #10 wires from the terminal block to the alternator ground. This way there is no reliance on the frame/body to provide a return path. Why didn't they do this on the truck originally? Because they wanted to save money!
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Lee W.
Lee W.

March 18th, 2012, 1:10 am #7

there is no need to run a separate ground wire when in fact the whole body and frame is the ground. But when you're dealing with a vehicle that is fifty to sixty years old and has been exposed to mud,snow,rain and heaven knows what else, anything is possible when dealing with the electrical system.

Lee
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John Weinrich
John Weinrich

March 18th, 2012, 2:35 pm #8

When I was a kid learning electricity I thought that there was something special about the "ground". In the commercial world of TV, radio, automobiles, and whatnot engineers always used the chassis for a electrical return. So when I became and engineer I learned that it was for economy reasons, mostly. A lot of sensitive circuits have to be isolated from the chassis so that signal currents are not influenced by the other currents running through the chassis. In automobiles there is no real sensitive circuits. It is important to remember that "ground" is not perfect. Although a automobile frame and body is very massive relative to a wire, it still can present significant resistance and the subject problem shows up. Sometimes the money gained is significant. Imagine a signal repeater in the middle of the Atlantic ocean to boost telephone signals. A wire is run with the cable to power the booster. That wire needs to be large because of the loss incurred by the great distance. There maybe hundreds of thousands of dollars for that one wire. To save money they only run one wire to the booster to power it and use the salt water ocean for the return power. Yes they loose significant power in the resistance in the ocean but it is worth it...
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Rob Lund
Rob Lund

March 18th, 2012, 9:59 pm #9

That was it. I ran a new wire to a good ground point and problem fixed.

Thanks to all.

Rob Lund
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Lee W.
Lee W.

March 19th, 2012, 11:31 pm #10

There's something very satisfying fixing a problem like that, at least for me. And besides you come away with a better understanding of how everything is tied together.
Lee
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