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Old 09-03-2009, 09:32 AM
Bill-E-BoB's Avatar
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Dim Headlights

Are the incredibly dim headlights in my '55 Caddy just normal for the vintage, or is there something wrong? High & low beams work just fine...but honestly I don't even have the visibility on high beams that my daily driver gives me on low beams.

My solution for this has always been to just not drive at night...but there's a big car show this weekend (Drive Invasion if any of y'all are in Atlanta) that I've been lookin' forward to forever, and after sunset there are a bunch of b-movies playing & I really want to stick around for that...so headlights would be good to get home.

So, longwinded story short...how can I improve my headlights? Should they really be this dim? Its a 12V system, brand new battery with double the CC Amps of stock, generators been replaced with an Alternator, everything is working fine...just my headlights are so dang dim. What can I do?

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Old 09-03-2009, 09:43 AM
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This is a common problem on older cars. The wiring is insufficient to deliver full voltage to the headlamps. The problem gets worse when the owner decides he needs halogen bulbs to cure the dim incandescent bulb problem. The dim situation now compounds because the existing wiring was not sufficient for the incandescent bulbs, and now he has added halogen bulbs which require even more current to operate properly.

The operation can be improved dramatically with some simple wiring and a couple of relays. This link details a little about how to do it. Also do a search in this forum for"brighter headlamps", it will return multiple hits with information on how to do this, it's been beat to death in this forum. If you do not understand the process shoot me a PM and I will help you out.

Here is a wiring diagram.


Last edited by 302 Z28; 09-03-2009 at 10:50 AM.
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Old 09-03-2009, 04:59 PM
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On older cars a lot of time the ground paths will deteriorate. If you have a volt meter, with the lights on, check for voltage at the headlight socket with one meter lead on the battery negative, should be close to battery voltage. Then check to see what the voltage is across the headlight socket terminals. If it is lower you have a ground issue. Dedicated ground circuits were rare in the older cars and a lot of them depended on the mechanical bond between the radiator support and the rest of the body for headlight grounding. I have seen this a lot on older cars. It will often show up as one bright light and 1 dim one.
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Old 09-03-2009, 05:52 PM
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the relay setup works great. i did this to my 68 cougar and with even the standard bulbs it was an amazeing difference , much brighter.
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Old 09-03-2009, 06:27 PM
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Old 09-03-2009, 08:10 PM
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If you have standard round headlamps with the three wire connector, LMCtruck.com sells a wiring kit and relay that just plugs into the existing wiring for the headlamps. Parts # is 36-3580

With the kit you plug into the stock wiring at the headlight and then connect the power for the relay directly to the battery. There is no need to cut or tap into the stock wires. It the same general setup as shown in the diagram from a previous post, but easier to install.

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