Headlights Flickering
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Tuned
Joined: Jan 2013
Posts: 286
Likes: 8
From: Chandler, AZ
Headlights Flickering
OK, just had a scary experience. Just installed new headlights (halogen bulbs) on my 66 F250. Got them aligned preliminarily and then went out for a ride tonight in search of a dark road to test them out. Unfortunately, once I found the dark road (after about 20 minutes), the lights started to go on and off randomly. Pulled over and found it was only the headlights and not the tail lights - those were fine. Luckily we had also installed some fog lights behind the grill and so had enough light to get home.
What could be causing the lights to flicker like this? The lamps were hot but I would expect that. Is it possible these halogen bulbs are stronger than before and causing some sort of issue. Best I can tell the light switch on the dash and the harness to the bulbs is original. Could there be an issue with the switch or harness? BTW, these headlights are the custom ones from LMC. Supposed to be more focused and brighter and uses a 55 watt halogen bulb.
What could be causing the lights to flicker like this? The lamps were hot but I would expect that. Is it possible these halogen bulbs are stronger than before and causing some sort of issue. Best I can tell the light switch on the dash and the harness to the bulbs is original. Could there be an issue with the switch or harness? BTW, these headlights are the custom ones from LMC. Supposed to be more focused and brighter and uses a 55 watt halogen bulb.
Posting Guru
Joined: Jan 2011
Posts: 2,315
Likes: 0
From: Rossmoor at Seal Beach
Check the ground wires to make sure they are well grounded and tight! check for bad connections... also for burnt wires... and then check the relay.. Most likely the ground wires are loose.. pretty common!
Thread Starter
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Tuned
Joined: Jan 2013
Posts: 286
Likes: 8
From: Chandler, AZ
Came across this in a post on the same topic. I was not aware that my truck originally had a relay. This post shows a way to add one. Nonetheless, I will track the wiring and grounds to be sure everything is good there. Thanks.
Whiter Whites, Brighter Brights .: Articles
Whiter Whites, Brighter Brights .: Articles
Posting Guru
Joined: Jul 2009
Posts: 1,005
Likes: 0
From: Ventura, CA
your truck shouldnt have a relay, just a headlight switch and the dimmer switch (the high/low toggle on the floor) i had the headlight switch act up and then my headlights cut out and came back on but i would say that the ground wires would be the most likely.
FYI adding relays like that whiter whites article suggests is the way to go, makes a HUGE difference
FYI adding relays like that whiter whites article suggests is the way to go, makes a HUGE difference
Cargo Master
Joined: Jul 2006
Posts: 3,014
Likes: 91
From: Concord, CA
My 68 Mustang and Cougar were known to have their lights flicker especially the dash lights. Add halogens, like I once did, then many things started to flicker. Quickly removed the halogens back in the 80's. Issues are 1) old point style voltage regulator and all my vehicles have Motorcraft electronic ones, 2) low output alternators in the 38-42 amp range back then, and 3) pulling power through the headlight switch first before sending to the headlights. Needless to say all 5 of my older cars have had relays, built by me, installed into them. That plus new headlight switches to eliminate old worn contacts in them.
Fleet Owner
Joined: Jun 1999
Posts: 24,552
Likes: 74
From: Creedmoor, North Carolina
Flickering lights, a very common problem from that era. I think rather than relay they came with resistors. Some folk have found relief by cleaning the dimmer switch, others replacing the light switch. I did the Whiter, Brighter relay thing shortly after I got my truck and stopped it cold, no issues since.
+5 on Whiter Whites, Brighter Brights .: Articles
John
+5 on Whiter Whites, Brighter Brights .: Articles
John
Laughing Gas
Joined: Dec 2010
Posts: 1,091
Likes: 14
From: Tucson, Arizona
There is a circuit breaker incorporated into your headlight switch. Especially if your switch is original, but even if it's been replaced, your C/B in the switch will wear out (and was marginal, even when new) and not be up to the job, especially if you're running lights which demand more juice than the original headlights did. Start with replacing your headlight switch. If the problem persists, you may need to include a relay.
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Thread Starter
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Tuned
Joined: Jan 2013
Posts: 286
Likes: 8
From: Chandler, AZ
There is a circuit breaker incorporated into your headlight switch. Especially if your switch is original, but even if it's been replaced, your C/B in the switch will wear out (and was marginal, even when new) and not be up to the job, especially if you're running lights which demand more juice than the original headlights did. Start with replacing your headlight switch. If the problem persists, you may need to include a relay.
Started the relay project today for all the positive reasons, but it still remains to be seen if the switch will need to be replaced. What is the quality of the repops?
NumberDummy; HELP what is the stock part number for the headlight switch in a late 1966 (May 1966) F250? And is NOS available?
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Fleet Owner
Joined: Jun 1999
Posts: 24,552
Likes: 74
From: Creedmoor, North Carolina
It's a much better alternative.
John
Senior User
Joined: Apr 2006
Posts: 142
Likes: 0
jowilker beat me to it! The circuit breaker in these trucks need a relay to run any bigger draw than stock lights. A new switch won't fix the problem, and a Chinese copy will likely be even worse than what you already have.
Laughing Gas
Joined: Dec 2010
Posts: 1,091
Likes: 14
From: Tucson, Arizona
There are a lot of "depends ons" involved here, but mostly to do with how much current draw your lights will have. For what it's worth (i.e., nothing) I installed a set of Sylvania Halogen headlights (bought from O'Rielly's cheap) in my '66 F100 after replacing my headlight switch with a Motorcraft (Ford Replacement) from National Parts Depot. P/N 11654-6. Cost $40.95. Not Chinese. Came in Motorcraft box. My wires are original but in good shape. So far they have worked fine - a caveat being I am old and don't drive at night any more, but my wife does. We have only driven it a few times at night but so far, so good. As the saying goes, your mileage (success rate) may vary. Current draw, wiring condition (and gauge), and switch condition (possibly including seperate circuit as JoWilker mentioned) will determine your needs. Good luck with it.
Thread Starter
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Tuned
Joined: Jan 2013
Posts: 286
Likes: 8
From: Chandler, AZ
OK - finished the Whiter Whites - Brighter Brights install tonight and took her for a test spin. The lights are definitely brighter and whiter and better yet, they STAYED ON Switch appears to be OK and the job was pretty easy. Didn't even need a beer like the instructions suggested! Like the instructions said I picked up a couple of 5 pin Bosch-type relays at O'Reilly's and while there also picked up a new pair of headlight connectors. The only thing I did wrong was not read the instructions and managed to get the red and green wires backwards. Had to do the test drive with the "brights" on so people would not flash me to death. That's an easy fix for tomorrow evening. Another bunch of great tips from you all. For others experiencing the dreaded flickering headlights I highly recommend this patch!
Switch appears to be OK and the job was pretty easy. Didn't even need a beer like the instructions suggested! Like the instructions said I picked up a couple of 5 pin Bosch-type relays at O'Reilly's and while there also picked up a new pair of headlight connectors. The only thing I did wrong was not read the instructions and managed to get the red and green wires backwards. Had to do the test drive with the "brights" on so people would not flash me to death. That's an easy fix for tomorrow evening. Another bunch of great tips from you all. For others experiencing the dreaded flickering headlights I highly recommend this patch!
More Turbo
Joined: Apr 2011
Posts: 707
Likes: 2
From: Sauk City, WI
Good deal. I was going to suggest the Whiter Whites article as well. Pretty much lays it out there in plain english. When I rewire my truck, I will be wiring relays in right away to avoid any of this potential headache.
Edit:
I know a few people have read that article and wondered where to get this stuff. Good source here:
http://www.madelectrical.com/catalog/rly-1.shtml
Edit:
I know a few people have read that article and wondered where to get this stuff. Good source here:
http://www.madelectrical.com/catalog/rly-1.shtml