Headlights flicker randomly. Change light switch?? Need small advice.

Fox Body · 03-15-2001, 08:54 AM

This is the first time somthing weird like this has ever happened to me. I'll have the headlights on and after about 20 minutes of driving, they'll start flickering randomly. Not the parking lights, just headlights. Then, if I cut them off for a few minutes, and then turn them back on, they'll stay on for a while, depending on how long I cut them off. Eg, if I cut them off for 5 minutes after they start flickering, they'll stay on w/ no problem for about 20-30 minutes, but if I cut them off after they start flickering and leave them off for only 1 minute, they'll start flickering when I cut them on again after 5 minutes of driving.

This of course really sucks b/c I don't only drive my car when it's nice, bright and sunny outside.

I am gonna change my light switch with the one on my junker '79 (the one I use for spare parts) b/c I'm pretty sure that is the problem. I haven't done this before so I may need some advice, that'll help it go a little quicker if I don't have to find out everything myself. Also, I'm thinking that this light switch has a fuse in it. Do you think I could just change the fuse or is it advised that I change the whole switch??

Sorry so long and drawn out, but I wanted to give details b/c if this has ever happened to you or you know what the problem is, you'd want details.

-------------------------------
'79 Mustang Coup
4" Cowl
Weld wheels (15x6;15x8)
Stock 5.8L
C4 w/ shift kit
1.5" MAC full length headers
Holley 750 CFM
Edelbrock intake
2.5" Off road H-pipe, 2-chamber Flowmasters
8.8" Rear end w/ 3.55 gears (Now that's more like it!!)

Front: 225/60/15 Rear: 255/60/15 Eagle GT II
14 x 4” K&N air filter (getting the Xtreme setup soon)

"Red, thou art my companion. Hasten now your quickened metamorphosis to Green that I may conquer all who dare abide there beside me. May they be left thither behind burnt black." ---Fox Body

jimberg · 03-15-2001, 09:14 AM

It wouldn't be likely that fuses are causing the flickering. They are either blown or not.

Replacing the switch is a good start. If the problem persists, it could also be the turn signal switch. Ford made these really bad and if you ever opened it you'd see carbon deposits from major arcing. Over time it will eventually fail completely. To test this theory, you may want to try jiggling the turn signal switch and see if your lights flicker as you jiggle.

I've had this happen to me twice over the 155K life of my car. The first time I just opened the switch and cleaned it up. The second time I just replaced it. I can't remember if the foglights would go on but not the headlights, but I think that is what happened since when I was driving there was some light coming from the front.

Oh, to remove the headlight switch, all you have to do is depress the tabs on the switch on either side and it should just slide out. You probably can do one side of the switch at a time. Use a small flathead screwdriver.

------------------
351W 89 Mustang GT Convertible

COP TZR · 03-15-2001, 09:50 AM

Hey, no one could answer the problem better than me. If it's a GT and foglights are on it's the factory Ford light relay because your over heating the headlight relay which causes headlights to flicker.
Second, if it's and LX than it's the actual headlight switch. I drove for 2 months pulling it out hold out the window cool off then plug back in NO JOKE. All you have to do is pull out a bit then look in and there is a clip, just stick a screw driver in and pry outward. Very easy, and don't piss around with old ones, or just cooling it off, I've done both a new one cost me $40.00CDN after 15%TAX so it's not worth the hassle. I do grab spare ones whenever I can though, you never know eh.

lager94GT · 03-15-2001, 03:00 PM

I had the same problem on my '79 Mustang except that sometimes the headlights would go out completely instead of just flickering. It was caused by a faulty indicator switch (in the steering column). If I recall, since I haven't had the '79 for a number of years, was that the brights and turn signals were on the same stalk. I picked up a replacement from the junkyard which solved the problem.

Fox Body · 03-15-2001, 05:44 PM

Much thanks to all who replied. I really appreciate it. This place rocks. I'll check it all out.

-------------------------------
'79 Mustang Coup
4" Cowl
Weld wheels (15x6;15x8)
Stock 5.8L
C4 w/ shift kit
1.5" MAC full length headers
Holley 750 CFM
Edelbrock intake
2.5" Off road H-pipe, 2-chamber Flowmasters
8.8" Rear end w/ 3.55 gears (Now that's more like it!!)

Front: 225/60/15 Rear: 255/60/15 Eagle GT II
14 x 4” K&N air filter (getting the Xtreme setup soon)

"Red, thou art my companion. Hasten now your quickened metamorphosis to Green
that I may conquer all who dare abide there beside me. May they be left thither
behind burnt black." ---Fox Body

[This message has been edited by Fox Body (edited 03-15-2001).]

03-16-2001, 03:21 AM

Yeah, that sounds like a relay problem or possibly a circuit breaker

------------------
'84 Mustang 5.0 T5, FMS aluminum radiator & 180* thermostat, 1 5/8 shortys/2.5" duals, '88 GT tail lights and wheels, Holley 4160 4 BBL, smog pump idler, more coming soon

Fox Body · 03-16-2001, 12:19 PM

Quote:

Originally posted by COP TZR:
Hey, no one could answer the problem better than me. If it's a GT and foglights are on it's the factory Ford light relay because your over heating the headlight relay which causes headlights to flicker.
Second, if it's and LX than it's the actual headlight switch. I drove for 2 months pulling it out hold out the window cool off then plug back in NO JOKE. All you have to do is pull out a bit then look in and there is a clip, just stick a screw driver in and pry outward. Very easy, and don't piss around with old ones, or just cooling it off, I've done both a new one cost me $40.00CDN after 15%TAX so it's not worth the hassle. I do grab spare ones whenever I can though, you never know eh.

Yeah, I'm betting all my money on that answer. I can try all I want to make it flicker when I first turn on the lights by turning it on and off, switching turn signal, high beam/low beam, etc, but it won't do it nothing. ONLY when I have been driving one for a long distance w/ the lights the whole time does it start flickering.
Thanks again for your (plural) input.

-------------------------------
'79 Mustang Coup
4" Cowl
Weld wheels (15x6;15x8)
Stock 5.8L
C4 w/ shift kit
1.5" MAC full length headers
Holley 750 CFM
Edelbrock intake
2.5" Off road H-pipe, 2-chamber Flowmasters
8.8" Rear end w/ 3.55 gears (Now that's more like it!!)

Front: 225/60/15 Rear: 255/60/15 Eagle GT II
14 x 4” K&N air filter (getting the Xtreme setup soon)

"Red, thou art my companion. Hasten now your quickened metamorphosis to Green
that I may conquer all who dare abide there beside me. May they be left thither
behind burnt black." ---Fox Body

Dangerous Dave · 03-16-2001, 03:03 PM

This happened to me as well in an 82 and my 88. In the 82-it started happening right after I bought it-ended up that the head lights that were in it were not halogen-just regular. Put Halogens in and problem solved. In my 88 GT it only did this when the foglights were on-I knew that the switch was a problem in those so I bought a new one...when I pulled the old one out I saw the pigtail that plugs into the switch had a couple little brown burn spots around one terminal. Took the new switch back and replaced the pigtail and it was as good as new.
It seems to me that if the lights are flashing on and off, the crcuit breaker is doing its job. They protect things from getting too hot so they shut it down until it cools off and then it will turn it back on again.

------------------
1988 GT-under construction

79Stang · 03-16-2001, 05:37 PM

Check the grounds on the lights... They are the wires on both sides of the front corner of the fender/engine bay... If that bolt comes loose you will get a flicker of your brights or loose the lights on and off... 79's are the worst for wiring!!!!

Smokedawg · 03-16-2001, 10:01 PM

Hey

For those of you who have been keeping up in my Blue Oval posts. The same "Friend" who stole my parts had that problem. His was actually the switch part where the windshield washer and turnsignal post was. I think he got it out of a junkyard for like 10 bucks or something

------------------
347 Stroker Motor: Balanced, 30lb Bosch Injectors, Cobra Computer, Cobra Transmission, GT40 Ported and Polished Upper and Lower, GT40 Milled Ported and Polished Heads, B303 Cam, BBK 1 5/8 Headers, March Underdrive Pulleys, Electric Fan, Accel Performance Coil, Accel 300+ Racing Wires, NGK Plugs, Ram Air, K&N Filter, 77mm Mass Air Unit, FlowMaster Exhaust w/offroad H-Pipe, Hurst Short Throw Shifter, 3:55 Gears, Ram Clutch, Cross Drilled Rotors, High Tolerant Painted Calipers and Drums.

03-15-2001, 08:54 AM	#1
Fox Body Mustang Maniac Join Date: Sep 2000 Location: GA, U.S.A Posts: 2,266	Headlights flicker randomly. Change light switch?? Need small advice. This is the first time somthing weird like this has ever happened to me. I'll have the headlights on and after about 20 minutes of driving, they'll start flickering randomly. Not the parking lights, just headlights. Then, if I cut them off for a few minutes, and then turn them back on, they'll stay on for a while, depending on how long I cut them off. Eg, if I cut them off for 5 minutes after they start flickering, they'll stay on w/ no problem for about 20-30 minutes, but if I cut them off after they start flickering and leave them off for only 1 minute, they'll start flickering when I cut them on again after 5 minutes of driving. This of course really sucks b/c I don't only drive my car when it's nice, bright and sunny outside. I am gonna change my light switch with the one on my junker '79 (the one I use for spare parts) b/c I'm pretty sure that is the problem. I haven't done this before so I may need some advice, that'll help it go a little quicker if I don't have to find out everything myself. Also, I'm thinking that this light switch has a fuse in it. Do you think I could just change the fuse or is it advised that I change the whole switch?? Sorry so long and drawn out, but I wanted to give details b/c if this has ever happened to you or you know what the problem is, you'd want details. ------------------------------- '79 Mustang Coup 4" Cowl Weld wheels (15x6;15x8) Stock 5.8L C4 w/ shift kit 1.5" MAC full length headers Holley 750 CFM Edelbrock intake 2.5" Off road H-pipe, 2-chamber Flowmasters 8.8" Rear end w/ 3.55 gears (Now that's more like it!!) Front: 225/60/15 Rear: 255/60/15 Eagle GT II 14 x 4” K&N air filter (getting the Xtreme setup soon) "Red, thou art my companion. Hasten now your quickened metamorphosis to Green that I may conquer all who dare abide there beside me. May they be left thither behind burnt black." ---Fox Body

03-15-2001, 09:14 AM	#2
jimberg Registered Member Join Date: Oct 1998 Location: Rogers, MN Posts: 2,089	It wouldn't be likely that fuses are causing the flickering. They are either blown or not. Replacing the switch is a good start. If the problem persists, it could also be the turn signal switch. Ford made these really bad and if you ever opened it you'd see carbon deposits from major arcing. Over time it will eventually fail completely. To test this theory, you may want to try jiggling the turn signal switch and see if your lights flicker as you jiggle. I've had this happen to me twice over the 155K life of my car. The first time I just opened the switch and cleaned it up. The second time I just replaced it. I can't remember if the foglights would go on but not the headlights, but I think that is what happened since when I was driving there was some light coming from the front. Oh, to remove the headlight switch, all you have to do is depress the tabs on the switch on either side and it should just slide out. You probably can do one side of the switch at a time. Use a small flathead screwdriver. ------------------ 351W 89 Mustang GT Convertible

03-15-2001, 09:50 AM	#3
COP TZR Registered Member Join Date: Mar 2001 Location: Canada eh¿ Posts: 22	Hey, no one could answer the problem better than me. If it's a GT and foglights are on it's the factory Ford light relay because your over heating the headlight relay which causes headlights to flicker. Second, if it's and LX than it's the actual headlight switch. I drove for 2 months pulling it out hold out the window cool off then plug back in NO JOKE. All you have to do is pull out a bit then look in and there is a clip, just stick a screw driver in and pry outward. Very easy, and don't piss around with old ones, or just cooling it off, I've done both a new one cost me $40.00CDN after 15%TAX so it's not worth the hassle. I do grab spare ones whenever I can though, you never know eh.

03-15-2001, 03:00 PM	#4
lager94GT Registered Member Join Date: Mar 2001 Location: LI, NY Posts: 3	I had the same problem on my '79 Mustang except that sometimes the headlights would go out completely instead of just flickering. It was caused by a faulty indicator switch (in the steering column). If I recall, since I haven't had the '79 for a number of years, was that the brights and turn signals were on the same stalk. I picked up a replacement from the junkyard which solved the problem.

03-15-2001, 05:44 PM	#5
Fox Body Mustang Maniac Join Date: Sep 2000 Location: GA, U.S.A Posts: 2,266	Much thanks to all who replied. I really appreciate it. This place rocks. I'll check it all out. ------------------------------- '79 Mustang Coup 4" Cowl Weld wheels (15x6;15x8) Stock 5.8L C4 w/ shift kit 1.5" MAC full length headers Holley 750 CFM Edelbrock intake 2.5" Off road H-pipe, 2-chamber Flowmasters 8.8" Rear end w/ 3.55 gears (Now that's more like it!!) Front: 225/60/15 Rear: 255/60/15 Eagle GT II 14 x 4” K&N air filter (getting the Xtreme setup soon) "Red, thou art my companion. Hasten now your quickened metamorphosis to Green that I may conquer all who dare abide there beside me. May they be left thither behind burnt black." ---Fox Body [This message has been edited by Fox Body (edited 03-15-2001).]

03-16-2001, 03:21 AM	#6
84stang83zephyr Guest Posts: n/a	Yeah, that sounds like a relay problem or possibly a circuit breaker ------------------ '84 Mustang 5.0 T5, FMS aluminum radiator & 180* thermostat, 1 5/8 shortys/2.5" duals, '88 GT tail lights and wheels, Holley 4160 4 BBL, smog pump idler, more coming soon

03-16-2001, 03:03 PM	#8
Dangerous Dave Registered Member Join Date: Sep 1999 Location: Minneapolis, MN Posts: 121	This happened to me as well in an 82 and my 88. In the 82-it started happening right after I bought it-ended up that the head lights that were in it were not halogen-just regular. Put Halogens in and problem solved. In my 88 GT it only did this when the foglights were on-I knew that the switch was a problem in those so I bought a new one...when I pulled the old one out I saw the pigtail that plugs into the switch had a couple little brown burn spots around one terminal. Took the new switch back and replaced the pigtail and it was as good as new. It seems to me that if the lights are flashing on and off, the crcuit breaker is doing its job. They protect things from getting too hot so they shut it down until it cools off and then it will turn it back on again. ------------------ 1988 GT-under construction

03-16-2001, 05:37 PM	#9
79Stang The Stang Gang Join Date: Jan 1999 Location: St. Petersburg Posts: 63	Check the grounds on the lights... They are the wires on both sides of the front corner of the fender/engine bay... If that bolt comes loose you will get a flicker of your brights or loose the lights on and off... 79's are the worst for wiring!!!!

03-16-2001, 10:01 PM	#10
Smokedawg Tires Fear Me... Join Date: Jan 2001 Posts: 867	Hey For those of you who have been keeping up in my Blue Oval posts. The same "Friend" who stole my parts had that problem. His was actually the switch part where the windshield washer and turnsignal post was. I think he got it out of a junkyard for like 10 bucks or something ------------------ 347 Stroker Motor: Balanced, 30lb Bosch Injectors, Cobra Computer, Cobra Transmission, GT40 Ported and Polished Upper and Lower, GT40 Milled Ported and Polished Heads, B303 Cam, BBK 1 5/8 Headers, March Underdrive Pulleys, Electric Fan, Accel Performance Coil, Accel 300+ Racing Wires, NGK Plugs, Ram Air, K&N Filter, 77mm Mass Air Unit, FlowMaster Exhaust w/offroad H-Pipe, Hurst Short Throw Shifter, 3:55 Gears, Ram Clutch, Cross Drilled Rotors, High Tolerant Painted Calipers and Drums.