Topic: Dim headlights on 40 Ford


bwhitworth    -- 01-21-2013 @ 11:37 AM
  I went to a car show last Saturday night and stayed till after dark. I don't like to drive my old car after dark. I left the show which was in the city and did not notice how dim the head lights were. By the time I turned onto the road to my house I could hardly see the mail boxes. I checked the voltage at the head lights and found only 4 volts. Then I put a jumper wire from the battery to the headlight and I had a very bright light. What can I do to get the full 6 volts to the headlights? I watched the amp gauge as I raced the engine with the lights on, the hand stayed in the yellow zone. Is converting to a 12v system the only answer?
Thanks,
Bob


kubes40    -- 01-21-2013 @ 2:05 PM
  Converting to 12v. is never THE answer. It is a cure but creates other problems.

I would suggest being 100% certain each lamp is very well grounded. Those old bolts and corroded areas significantly reduce the proper grounding required.
I would also check the headlamp circuit breaker for proper output.

Are the butt connectors in the wire harness tight? Are the metal connectors within the rubber covers clean? I always solder these areas and push the rubber insulator back over the connections.

Last but not least, be certain the headlamp switch is properly grounded.

Supereal... what say you? I know you are sharper than me on this stuff. What did I possibly over look that may require inspection?


supereal    -- 01-21-2013 @ 4:53 PM
  Thanks, Mike. You covered most weak spots, and I'd add one of the worst offenders, the dimmer switch. Bob has already found that direct feed from the battery gives good lights. He can place the probes of a voltmeter across all the parts of the lighting circuit to find the worst offenders. Any reading on the meter indicates loss at that leg. Being sure the light buckets are well grounded is also vital. We run separate grounds to each because most front fenders are not providing adequate ground. I went thru all parts of the circuit in my '47, and finally installed relays. I now have very bright headlights instead of the old yellow ones.


TomO    -- 01-22-2013 @ 9:12 AM
  Scroll down to 1933 headlight bulb for a procedure to determine where the voltage drop is occurring.

You have already determined that the voltage circuit is the problem by checking the voltage at the lamps and using a jumper to see that the bulbs get bright when they get the proper voltage. This means that your grounds are probably fine.

You can use a jumper wire to perform the same tests, but I don't recommend it. A slight misstep in connecting the jumper could cause a spark and a fire. The voltmeter is safer.

Any of the bullet connector and the light and dimmer switches could be causing the problem. I have had good success cleaning the dimmer switch and lubricating the contacts with vaseline or a corrosion inhibiting grease. I like to coat the bullet connectors with Copper shield from Eastwood.

A quick check of the bullet connectors is to feel them with the headlights on. If they are warm to the touch, they need cleaning.

Tom

This message was edited by TomO on 1-22-13 @ 9:17 AM


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