Dim Headlights

[crazyboutwagons]

Did a adjustment today on the headlights because the pattern was off and had trouble seeing at night the driver,s side was low & passenger was good. My neighbor said they still look dim though. I checked the after market gauge panel & when lights where turned on it dropped from 14 volts to 12 volts the battery checked out as good when a load test was done.Could it be the headlight switch or the dimmer switch or both.Any suggestions

 

[darth_linux]

Did an adjustment today on the headlights because the pattern was off and had trouble seeing at night the driver,s side was low & passenger was good. My neighbor said they still look dim though. I checked the after market gauge panel & when lights where turned on it dropped from 14 volts to 12 volts the battery checked out as good when a load test was done.Could it be the headlight switch or the dimmer switch or both.Any suggestions

If you’ve not yet done the “ammeter bypass” upgrade and installed headlight relays on your car, I would make that the very first thing you do.

Performing a quick forum search on either topic will net you lots of results on how to do the job, including my own build thread on my 66 Newport. '66 Newport 2 Door hardtop

 

[crazyboutwagons]

I have read that about the bypass numerous times not being Electrical inclined i was a bit hesitant to do it myself. I got to seek some help from my neighbor.
Thanks Darth

 

[darth_linux]

I have read that about the bypass numerous times not being Electrical inclined i was a bit hesitant to do it myself. I got to seek some help from my neighbor.
Thanks Darth

Your welcome. It's pretty simple if you do it the way I did mine. About 7' of 10ga. wire running from the back of your alternator over to your starter relay, plus the fusible link. A couple of butt connectors and you're good to go. The headlight relay is also super easy if you buy the kit. Nearly plug and play. Then your headlights won't dim at idle or when there is a high electrical load on the car. You can do it!

 

[FURYGT]

Did a adjustment today on the headlights because the pattern was off and had trouble seeing at night the driver,s side was low & passenger was good. My neighbor said they still look dim though. I checked the after market gauge panel & when lights where turned on it dropped from 14 volts to 12 volts the battery checked out as good when a load test was done.Could it be the headlight switch or the dimmer switch or both.Any suggestions

What is the amperage output of your alternator? Do you have an OEM mechanical voltage regulator or an electronic solid state voltage regulator?

If we are talking about your 1968 Sport Suburban, the headlights are usually dim at idle or if you have the defroster on high. In 1968, a non A/C Fury would have a 37 amp alternator and an A/C car would have a 45 amp alternator so some dimming at idle is normal.

If you are going to Carlisle next week come and talk to me at swap meet space G126. I will have the solid state stock appearing voltage regulators there.

 

[CBODY67]

The dimmer switch is easy to change and not very expensive. Might replace it as a matter of course. One night, when I came out of the mall after dark, the low beams didn't work. Nor the high beams either. Cost me a tow bill and a new switch the next morning.

"Dim" headlights? Almost every OEM headlight from the 1980s is dim by modern HID projector beam standards. And THEN some like to put "super white" bulbs in them too!

CBODY67

 

[Gerald Morris]

To sum up the Wise Words thus far expressed...

1. Replace aged headlight beam selector switch and upgrade to solid state voltage regulator if not already done

2. Perform ammeter bypass, then install headlight relay(s)

3. upgrade aged, obsolescent low current alternator to at least 60 to 100 amp one. These can be had in roundback form factor or squareback at least for over 60 amps/

4. If the perfectly good old DOT approved incandescent PAR sealed beam lamps of the C body Era don't then produce enough light for you, one can buy some dangerously over bright LED lamps which can fit the older 5.75" round sealed beam form. This last step is the only one I won't do for myself, being ecstatic over how well my NOS Westinghouse 400X low/high beam lamps work after having effected Steps 1-3. With plenty current, the old school lamps shine very nicely, and at the proper spectrum for human eyes at night, unlike most of the modern lamps. The spectrum from LED lamps has to be produced from discrete sources, which don't overlap so naturally as the crude but effective Edisonian method of heating wire filaments to incandescence. I usually like quantum effect light sources for most purposes, but not driving light.

 

[CBODY67]

Back when the old Western Auto stores were all being closed-out, I scored some OEM replacement halogen headlights for my '67 Newport. Nothing special, just normal (for the time) halogen replacements. I was glad to see that the beam pattern had some aspects of the E-code Cibies I had in another car. Sharper upper cut-off with a little flare to the rh side. After aiming them like I liked them to be aimed, everything worked well. No other modifications required or needed.

CBODY67

 

[Big_John]

Before you start throwing parts at it or making changes, check the voltage at the battery. Do it with the lights off at idle, then check it at a fast idle. Now turn the lights on and check it again.

What you may have is a low voltage problem. A simple multimeter from Harbor Fright will do just fine... You don't need anything fancy. You should have one anyway.

From there, you figure out what your problem is. You may have a bad regulator or a bad diode in the alternator or a number of other issues.

No one wants to suggest or actually do the work first.

 

[tbm3fan]

Before you start throwing parts at it or making changes, check the voltage at the battery. Do it with the lights off at idle, then check it at a fast idle. Now turn the lights on and check it again.

What you may have is a low voltage problem. A simple multimeter from Harbor Fright will do just fine... You don't need anything fancy. You should have one anyway.

From there, you figure out what your problem is. You may have a bad regulator or a bad diode in the alternator or a number of other issues.

No one wants to suggest or actually do the work first.

Along with that you can also measure the voltage at one of the headlight connectors while the car is running to see what you have there. Every time I did that I would get around 9.5V at those connectors. With my relays I get what my battery is getting when the car is running which is in excess of 13V. Of course I rarely drive my vintage cars at night.