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#1 |
Post Whore
![]() Join Date: Feb 2000
Location: Rose Hill, KS, USA
Posts: 12,684
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Headlight problem
A buddy is having a problem getting his headlights to work. If he just pulls the light switch halfway out, to the parklight position, the parklights come on and the blinkers all work. If he pulls the light switch all the way out, no park lights and no headlights but he does have tail lights. Bottom line, everything works except the park lights and headlights with the switch fully on. Tony got his tester out and it doesn't appear that he is getting juice to the headlights but it doesn't make sense why the park lights work with the switch half way out but not with it all the way out. There's one wire plug that comes out of the harness and goes through the front radiator support that connects to the headlight assembly. He has no juice to it as far as he can tell. The park lights feed from a different wire, from a different wire harness. He is baffled as he has put in three different light switches in the truck and they all act the same, no headlights or park lights with the switch in the full out position.
Any thoughts?
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1970 Blazer with a 400 sbc and 4" lift 1980 Pontiac Trans Am, 455 Oldsmobile 2012 Kawasaki Concours 14 |
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#2 |
Registered User
![]() Join Date: Jan 2001
Location: Middlesex, NC
Posts: 231
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Has this ever worked for him? If not, trace all the wires completely to make sure they are all there and not messed with. Also check for any cracks or burn marks in the wirring, at 30+ years old, these things lose insulation and arc out in the wierdest ways sometimes.
Orlando
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70 C-20 Custom Camper Build thread: http://67-72chevytrucks.com/vboard/s...d.php?t=300251 |
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#3 |
Post Whore
![]() Join Date: Feb 2000
Location: Rose Hill, KS, USA
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He is just getting the truck running, so no prior knowledge on when they last worked.
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1970 Blazer with a 400 sbc and 4" lift 1980 Pontiac Trans Am, 455 Oldsmobile 2012 Kawasaki Concours 14 |
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#4 |
Registered truck nut
Join Date: Dec 1999
Location: Mt. Vernon, Washington, USA
Posts: 1,584
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Have you checked out the dimmer switch. This always seems to be the culprit
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MOUNT VERNON, WASH. STATE Need a part? Just PM me |
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#5 |
CCRider
Join Date: Feb 2000
Location: Olive Branch,MS,USA
Posts: 2,232
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Yep...what LeRoy said
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72 GMC Sierra SWB almost finished---- 84 Softail Olive Branch MS |
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#6 |
Post Whore
![]() Join Date: Feb 2000
Location: Rose Hill, KS, USA
Posts: 12,684
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Are you both referring to the dimmer switch that dims the dash lights or the high/low switch that changes the headlights from high/low beam?
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1970 Blazer with a 400 sbc and 4" lift 1980 Pontiac Trans Am, 455 Oldsmobile 2012 Kawasaki Concours 14 |
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#7 |
Senior Member
Join Date: Jan 2003
Location: daytonabeach
Posts: 22,956
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footoperated dimmer
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71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY |
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#8 |
Registered User
Join Date: Nov 2003
Location: Green Valley, AZ
Posts: 28
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My 70 Chev did the same thing. I replaced the headlight switch.
Works fine now.
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1970 Chev C20, 2wd, LB, 350 4BBL, muncie 4spd, 4:10 limited slip. 2002 Chev 2500HD 8.1L Allison, 4X4. 1996 Chev S10 Blazer, 4X4. 2006 Jeep LJ Rubicon |
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#9 |
Registered truck nut
Join Date: Dec 1999
Location: Mt. Vernon, Washington, USA
Posts: 1,584
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Ya, foot operated. Take a jumper wire and put it in the top prong slot and then into one of the lower two. One is high and other is low beam. Doesn't matter which. Just a quick check to see if that's the problem. This just happened to me and I checked everything except that switch. Damn rookie mistake on my part. lol
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MOUNT VERNON, WASH. STATE Need a part? Just PM me |
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#10 |
Account Suspended
Join Date: Nov 2003
Location: Texas
Posts: 17
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What year is the truck? It might be a year that did have parking lights with headlights... My 67 Chevys park lights go out when my head light come on......
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#11 |
Designated A-hole!
Join Date: Mar 2003
Location: South Mississippi
Posts: 36,450
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My vote is for the dimmer switch.
BTW welcome to the board to 8.1pwr.
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"If it ain't broke, fix it 'til it is!" Being stupid ain't illegal. ![]() We're Still Debt Free Except for the House!!! www.daveramsey.com 70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e 93 S-10 "Poppaw's Truck" |
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#12 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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If I read this properly, the parking lights work fine, but when the headlamps are turned on, the parking lights go out. (Do the tail lights stay on?)
in 67 the front markers turne off, that is the way they are designed. If it is a 68 or newer, or a 67 and the tail lights also go out...then there is somethign askew. |
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#13 |
Registered User
Join Date: Oct 2003
Location: Carmichael, California
Posts: 3,006
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i just had the same problem with my 68. someone here pointed me in the right direction and it was the foot dimmer. the plug was melted on the headlight wire and burned the terminal. i cut the wires, used 3 female connecters, cleaned all the dimmer switch terminals and now my lights work. it`s probably only a matter of time before it does it again but i`m planning on rewireing the whole truck soon and it`s just my project truck anyway so it doesn`t get much use right now.
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Anthony |
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#14 |
Post Whore
![]() Join Date: Feb 2000
Location: Rose Hill, KS, USA
Posts: 12,684
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As usual, my truck buddies come through! Dimmer switch on the floor was bad. This was on a 65 and neither of us had any idea that on 67 and older vehicles the parking lights on the front went out when the headlights are on.
Andy, Tony was getting no headlights or front parking lights when the switch was fully on, parking lights did work in the half way position. I believe his rear parking lights stayed on when he had switch fully on. Tony's got it all straightened out now. Thanks guys! Tony wants to wire the truck so the parking lights stay on when the headlights are on. We assume he should just tap into the rear parking light wiring harness as those are on whether the headlights are on or not. Sound good to you all?
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1970 Blazer with a 400 sbc and 4" lift 1980 Pontiac Trans Am, 455 Oldsmobile 2012 Kawasaki Concours 14 |
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#15 |
Weapons Of Construction
Join Date: Apr 2000
Location: Colorado, USA
Posts: 1,095
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I had a 60 Chevy that worked the same way.
It's been so long ago, but I think I put a newer switch in ('cause there weren't any old ones around). I can't remember, but I may have had to splice in a newer plug to get it to work. In any case, when I was done, the park lights stayed on in front when the headlights were on, much to my surprise.
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1971 GMC 2500, 402/TH400 4.10 Daily Driver Lafayette, CO |
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#16 |
Registered User
Join Date: Feb 2000
Location: Center City, MN, USA
Posts: 3,254
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Now that your buddy has it all working do the conversion to relay operated headlights.
I just completed this project on my truck. I was amazed at how small the wires are that run to/from the headlight switch, dimmer, and headlights. What a joke! The beauty about this conversion is my switch, dimmer, and wiring should last forever because there aren't that many amps flowing through them any more. Not to mention my headlights are now a whole lot brighter. Before the conversion I had 10.8 volts at the headlight with the engine off. After I had 11.8. I didn't bother to take readings with the engine on. My eyes tell me the headlights are WAY brighter.
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'70 cab, '71 chassis, 383, TH350, NP205. '71 Malibu convertible '72 Malibu hard top Center City, MN |
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#17 |
Post Whore
![]() Join Date: Feb 2000
Location: Rose Hill, KS, USA
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What is the conversion to relay operated headlights?
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1970 Blazer with a 400 sbc and 4" lift 1980 Pontiac Trans Am, 455 Oldsmobile 2012 Kawasaki Concours 14 |
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#18 | |
Registered User
Join Date: Feb 2000
Location: Center City, MN, USA
Posts: 3,254
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Quote:
I drove my truck after dark today for the first time since I did this conversion. I can't believe it took me 10 years to do this.
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'70 cab, '71 chassis, 383, TH350, NP205. '71 Malibu convertible '72 Malibu hard top Center City, MN |
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#19 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Read this...a great article on relays for your headlights.
http://www.classictruckshop.com/club...ead/lights.htm |
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#20 | |
Registered User
Join Date: Feb 2000
Location: Center City, MN, USA
Posts: 3,254
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Quote:
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'70 cab, '71 chassis, 383, TH350, NP205. '71 Malibu convertible '72 Malibu hard top Center City, MN |
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#21 |
Senior Member
Join Date: Jun 2001
Location: Shelbyville, KY
Posts: 3,269
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Bet this would work for tail lights, brake lights, dash lights etc. Now to find a relay that will work----any suggestions--radio shack, etc.?
Maybe this explains why the 928Porsche's had 30+ relays located under the floor/firewall carpet on the pass side |
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#22 |
Is a bullfrog waterproof?
Join Date: Nov 2000
Location: OLATHE, KANSAS
Posts: 1,130
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Huck you can find these at most auto parts stores such as NAPA or O'Reiley's. They are a single pole double throw (SPDT) relay and a lot of the car manufacturers are using them. They are about 1" square, black, and usually have a mounting ear of some sort. Bosch and Potter-Brumfield are two of the manufacturers.
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"It is better to remain silent and be thought a fool, than to open one's mouth and remove all doubt." Ben Franklin __________________ 1970 Chevy shortbed 2002 Harley Custom Chopper (Long sucker) 1998 K2500 5.7L 5-speed Longbed 1st two are My son's toys...they just live in my garage! 1997 GMC K1500 Suburban 1993 S-10 Blazer 4D (youngest son's daily driver) 2000 Dodge Ram 4WD Ext. Cab (5.9L) Wife is a late year 1951 |
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#23 |
Registered User
Join Date: May 2000
Location: Petrolia,Ontario,Canada but working in Port Huron,Mi.
Posts: 1,771
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I'm just finishing rewiring my truck and did the relay thing as well.
Ya the lights are brighter.I'm waiting to get it on the road again at night so I can see the difference. I used bosch 30 amp relays.You can get automotive relays at any parts store or local eletronics store.Usually $3-5 each. It's a bit of a tagled mess here but.The 1st two are the high and low beam then the driving lights then the power distribution block. ![]() I basiically ripped out all the orig. eng bay wiring and started from scratch.I used the orig. head light wire to "trigger" the relays but that's about it. I ran some 12g wire from the relays to the headlights.This helps diliever more jiuce to the lights. I also ran a 8g wire from the alt. to a distribution block on the firewall.This power distribution block now feed the whole truck and is remotely sensed by the alt.What that means is as the power is sucked from the distribution block the alt. sense wire connected there will bump up the alt. output automatically to keep all the circiuts happy. Heres the 8g alt. wire with a 12g fusable link protecting it. ![]() I have loads more pic's but this isn't my post. I'll make my own post when I've completed things.:p
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71 blazer,350SBC,approx.375HP,700R4,factory GM TPI.Dual electric fans,33x12.5x15 ATR on stock suspension. Petrolia,Ontario,Canada but working in Port Huron,MI. See ALL my Blazer pic's HERE Last edited by BobbyK; 11-20-2003 at 12:52 PM. |
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#24 |
Post Whore
![]() Join Date: Feb 2000
Location: Rose Hill, KS, USA
Posts: 12,684
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Interesting, my lights are so dim, this would be a great upgrade.
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1970 Blazer with a 400 sbc and 4" lift 1980 Pontiac Trans Am, 455 Oldsmobile 2012 Kawasaki Concours 14 |
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#25 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,693
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Jack, if you were to clean up the grounds on your front end, you'd be amazed at the light you'll get even without the relays. (I still plan on doing hte relays...but my truck lights up the road better than my wife's 96 Contour)
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