'78 headlight issues
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Tuned
Joined: Mar 2003
Posts: 394
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From: austin
'78 headlight issues
My new-to-me '78s headlights only work with the high beams on - the low beams don't work at all. I've replaced a bulb, but it didn't fix it. Is this a common problem in these trucks?
TM
TM
Freshman User
Joined: Jan 2004
Posts: 49
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From: Southeast MO
Hey guys, my truck is kind of like this but it seems like a heat sink problem, on low's my lights will work all night, but after a few min on high the lights will flicker on and off. If I turn it back to lows doesn't necessarily make the problem go away, that only happens if I open the vent under the dash on the kick panel and blow cool air under the dash, the problem will go away again. I am thinking the light switch in the dash is bad, what's your opinions?
Chris
Chris
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Joined: Jan 2008
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No heat sink.
The breaker is built into the switch ,that's why the flcikering lights & that's why the cool air helps it out.
GM used a relay system, & this is something I encourage users to do to their trucks.
Run the Lights off of relays.
http://faq.auto.light.tripod.com/headlamp-harness.html
The breaker is built into the switch ,that's why the flcikering lights & that's why the cool air helps it out.
GM used a relay system, & this is something I encourage users to do to their trucks.
Run the Lights off of relays.
http://faq.auto.light.tripod.com/headlamp-harness.html
Posting Legend
Joined: Sep 2001
Posts: 30,255
Likes: 37
The breaker in the light switch is bad. You can replace the light switch or do like Dennis says and use relays. The relay system is worth the effort if you do it right. There are tech papers and many posts here on relays for headlights.
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Freshman User
Joined: Jan 2004
Posts: 49
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From: Southeast MO
ok next question. the lighting is at best marginal on this truck. What is the best option for upgrade? And as soon as I get a chance I will do a search on this forum for this but I am just wondering who has upgraded the lights and is happy with that upgrade?
Chris
Chris
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Joe Kucinski
New User
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When you say lighting is marginal please be more specific.
headlights,interior lights,marker lights ?
I suggest to do the modification.
It costs about $25.00 and takes an afternoon to do.
Just make sure you get the good BOSCH relays and the new Fuse (Blade fuse) wiring for the job.
I will post 2 more sites than the one above.
headlights,interior lights,marker lights ?
I suggest to do the modification.
It costs about $25.00 and takes an afternoon to do.
Just make sure you get the good BOSCH relays and the new Fuse (Blade fuse) wiring for the job.
I will post 2 more sites than the one above.
New User
Joined: Jan 2008
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Freshman User
Joined: Jan 2004
Posts: 49
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From: Southeast MO
I am talking about the headlights. I dislike the yellowish glow and the fact that they don't seem to light as well as my 94. I know it is 20+ years older, and that makes it hard to see well.
Chris
Chris
