Would Alternator cause this?
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Junior User
Joined: Nov 2002
Posts: 77
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From: South Central, PA
Would Alternator cause this?
My 79 F150 has the infamous ford flickering headlights again. This originally happened over a year ago. At the time I replaced the headlight switch which corrected the problem until yesterday.
The headlights go off for a second or two then come back on. They don't dim or get weak, they just go off and on repeatedly when driving at highway speeds but it doesn't happen until I've been driving for awhile.
My question is if the alternator is the problem wouldn't the dash/interior lights also go out as well? The dash lights never go out.
The headlights go off for a second or two then come back on. They don't dim or get weak, they just go off and on repeatedly when driving at highway speeds but it doesn't happen until I've been driving for awhile.
My question is if the alternator is the problem wouldn't the dash/interior lights also go out as well? The dash lights never go out.
Cargo Master
Joined: Aug 2003
Posts: 3,237
Likes: 3
From: Belleville, Ontario
Not likely there's a problem with the alternator being that you do have dash lights & anything else electrical like the ignition system.
Did you upgrade to a higher output alt. &/or bigger battery? This makes the headlights brighter & puts more heat in the headlight switch. It also makes other electrical accs. work better too.
There's a thread about putting relays in the wiring system for the headlights to give you brighter lights. I think it's on the right of each page in "tech articles"?
AL.
Here's the link... https://www.ford-trucks.com/article/...r_Brights.html
Did you upgrade to a higher output alt. &/or bigger battery? This makes the headlights brighter & puts more heat in the headlight switch. It also makes other electrical accs. work better too.
There's a thread about putting relays in the wiring system for the headlights to give you brighter lights. I think it's on the right of each page in "tech articles"?
AL.
Here's the link... https://www.ford-trucks.com/article/...r_Brights.html
Last edited by Dealford; Nov 30, 2004 at 08:37 PM.
Moderator
Joined: Jan 2001
Posts: 57,025
Likes: 2,756
From: Virginia
Make sure you don't have any extra lighting on the headlight switch.
My guess would be your headlight switch plug is not in very good shape. Loose connections at the plug will cause heat, which will make the circuit breaker in the headlight switch cut out.
My guess would be your headlight switch plug is not in very good shape. Loose connections at the plug will cause heat, which will make the circuit breaker in the headlight switch cut out.
Elder User
Joined: Apr 2004
Posts: 970
Likes: 3
Franklin has hit it on the head, for some reason the Ford headlight switch internal
breakers are very sensitive to overloads and bad connections. Extra lighting causes a problem. The push on connectors will never match the old screw type.
breakers are very sensitive to overloads and bad connections. Extra lighting causes a problem. The push on connectors will never match the old screw type.
Senior User
Joined: Oct 2004
Posts: 482
Likes: 2
Changing the switch will only be a temporary solution if the harness connector is bad. Check it out. If the harness connector is the problem I would do the relay installation thing mentioned previously as it would be easier than replacing the headlight switch harness connector.
