Headlight help! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Jemost 72 · 03-24-2003, 03:22 AM

Surely this has happened to someone, so I thought I'd ask....

When I first turn my headlights on, all is good. As I travel down the dark street, sometimes they turn off momentarily for no reason, sometimes they turn off when I hit a bump, then come back on. Sometimes they get me all the way home without any problems. When they do go off, I can hit my highbeams and they will come on and not flash off.

What I've done so far: replaced headlight switch(twice),
replaced dimmer switch, replaced drivers side headlight (had broken connection on light).

I thought after replacing the headlight switch and dimmer switch, it might be a ground problem..but why do the highbeams work?
After driving it home at night, I can push down on the front of the pasg side fender and make the headlights flash off...

Can anyone help me solve this mystery?

JimKshortstep4x4 · 03-24-2003, 07:52 AM

Have you cleaned your connectors yet?

Also, the brass terminals on the headlights themselves can have bad solder joints.

Jim

dmurphy68 · 03-24-2003, 08:45 AM

mine did that but i replaced my high beam switch and fixed all my problems
Darren

Blue Beard · 03-24-2003, 09:15 AM

Does sound like a ground problem except for the High Beams working, try using electrical grease on the connections.

You may have connection problems in the connectors..............

bobs409 · 03-24-2003, 09:22 AM

With the lights on, wiggle the plugs on the back of the headlights and see if they easily blink on/off. If so, clean the connectors in the plugs that attach to the headlight. Using a very thin, small screwdriver, you can insert it into the plug and depress a small locking tab, then pull the wire out. Clean each connector with a bit of sandpaper and reinstall. Do one at a time to avoid getting them switched around.

Other than that, try the bulkhead connector on the firewall. It could be causing the problem.

Jemost 72 · 03-25-2003, 02:52 AM

I cleaned the connectors, I've wiggled the plugs that go into the headlight with no results. I think I'll replace the front right headlight and another dimmer switch to rule them out.. what is the bulkhead connector on the firewall?
Thanks for the help!

Class of 69 · 03-25-2003, 11:53 AM

The key clue here may be the pressing down on the fender. The harness runs behind the fender, on top of the inner wheel well . Disconnect the harness plug at the firewall and pull it out the front of the fender by the regulator. Look for any worn or broken wires were it was hidden from view. Look for any indication of corrosion seeping thru the tape around the bundle, you know that greenish, crud that always makes your heart sink .

mrein3 · 03-25-2003, 01:53 PM

Check the dimmer switch on the floor.

BUXMAN66 · 03-25-2003, 02:24 PM

i've had similar prob.s, but mine was taken care of after i cleaned and reattached the grounding wire on each side where the wires pass through to the headlight itself.the grounding wire(each side has it's own)is attached to the inside of your core support.

bigvinnie · 03-25-2003, 08:09 PM

bulkhead connector is where the harness plugs into the firewall, by the master cylinder... you need to follow your wiring back from the headlights and verify that there are no bare wires, and also that connections and grounds are solid...

if the harness is original, you could have a brittle, exposed or corroded spot that would be hard to find...

if you don't find anything obvious, best bet is to buy a new replacement headlight harness so you know your wiring is not the culprit... they're easy to install, not expensive, and might save you some time and headaches...

krazy_texan · 03-25-2003, 09:44 PM

check your harness

Jemost 72 · 04-22-2003, 03:03 AM

Just an update for future reference: after replacement of 2 headlight switches, dimmer switch, both headlamps.. i may have found the problem.

On the wires that go across the radiator, a couple of them were caught under the drivers side upper radiator support. I have been flash-free for 2 nights now. I'm keeping my fingers crossed that was the problem!

03-24-2003, 03:22 AM	#1
Jemost 72 Southern Bowties Join Date: Jan 2003 Location: Fort Worth, TX Posts: 240	Headlight help! Surely this has happened to someone, so I thought I'd ask.... When I first turn my headlights on, all is good. As I travel down the dark street, sometimes they turn off momentarily for no reason, sometimes they turn off when I hit a bump, then come back on. Sometimes they get me all the way home without any problems. When they do go off, I can hit my highbeams and they will come on and not flash off. What I've done so far: replaced headlight switch(twice), replaced dimmer switch, replaced drivers side headlight (had broken connection on light). I thought after replacing the headlight switch and dimmer switch, it might be a ground problem..but why do the highbeams work? After driving it home at night, I can push down on the front of the pasg side fender and make the headlights flash off... Can anyone help me solve this mystery? __________________ 1972 Cheyenne 350/350

03-24-2003, 08:45 AM	#3
dmurphy68 Registered User Join Date: Nov 2002 Location: Middletown ohio Posts: 1,058	mine did that but i replaced my high beam switch and fixed all my problems Darren __________________ The very atmosphere of firearms everywhere restrains evil interference. When firearms go, all goes, we need them every hour. - George Washington No free man shall be debarred the use of arms - Thomas Jefferson Later Darren http://www.myspace.com/dmurphy68

03-24-2003, 09:15 AM	#4
Blue Beard Registered User Join Date: Jan 2003 Location: Washington State Posts: 8,834	Does sound like a ground problem except for the High Beams working, try using electrical grease on the connections. You may have connection problems in the connectors.............. __________________ 1970 Chev CST 2003 Harley Fatboy 1975 Chevrolet Step Van 1956 Chev Bel Air 1977 Blazer 2WD For Sale $3000.00 1978 Blazer 2WD For Sale $7000.00 1978 Silverado 2005 Monte Carlo

03-24-2003, 09:22 AM	#5
bobs409 1969 Custom 30 wrecker Join Date: Sep 2001 Location: Pottsville, Pa Posts: 2,611	With the lights on, wiggle the plugs on the back of the headlights and see if they easily blink on/off. If so, clean the connectors in the plugs that attach to the headlight. Using a very thin, small screwdriver, you can insert it into the plug and depress a small locking tab, then pull the wire out. Clean each connector with a bit of sandpaper and reinstall. Do one at a time to avoid getting them switched around. Other than that, try the bulkhead connector on the firewall. It could be causing the problem. __________________ Bob 63 Impala 283/PG/3.36 (under restoration) 66 Impala 327/PG/3.36 66 Chevelle SS 409/M22/3.55 69 Chevelle 307/PG/3.08 (future restoration) 69 C10 short stepside 454/TH350/3.73 69 Custom 30 tow truck 350/4 spd/4.10 (resto done, CRUISIN TIME!) 71 Cheyenne 20 fleetside 350/4 spd/4.10 71 Chevelle 6/PG/3.08 72 Chevelle 454/M21/4.10

03-25-2003, 02:52 AM	#6
Jemost 72 Southern Bowties Join Date: Jan 2003 Location: Fort Worth, TX Posts: 240	I cleaned the connectors, I've wiggled the plugs that go into the headlight with no results. I think I'll replace the front right headlight and another dimmer switch to rule them out.. what is the bulkhead connector on the firewall? Thanks for the help! __________________ 1972 Cheyenne 350/350

03-24-2003, 07:52 AM	#2
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Have you cleaned your connectors yet? Also, the brass terminals on the headlights themselves can have bad solder joints. Jim

03-25-2003, 11:53 AM	#7
Class of 69 Registered User Join Date: Mar 2003 Location: Stillwater MN Posts: 1,166	The key clue here may be the pressing down on the fender. The harness runs behind the fender, on top of the inner wheel well . Disconnect the harness plug at the firewall and pull it out the front of the fender by the regulator. Look for any worn or broken wires were it was hidden from view. Look for any indication of corrosion seeping thru the tape around the bundle, you know that greenish, crud that always makes your heart sink . __________________ 69 GMC K10 ..some restoration required....still..

03-25-2003, 01:53 PM	#8
mrein3 Registered User Join Date: Feb 2000 Location: Center City, MN, USA Posts: 3,254	Check the dimmer switch on the floor. __________________ '70 cab, '71 chassis, 383, TH350, NP205. '71 Malibu convertible '72 Malibu hard top Center City, MN

03-25-2003, 02:24 PM	#9
BUXMAN66 go bucks! Join Date: Jan 2002 Location: MIAMISBURG OHIO USA Posts: 803	i've had similar prob.s, but mine was taken care of after i cleaned and reattached the grounding wire on each side where the wires pass through to the headlight itself.the grounding wire(each side has it's own)is attached to the inside of your core support. __________________ '68 swb 1/2t 350/350th '86 lngbd 3/4 TON parts getter '49 gmc 1/2 t 5 window 350/350th '96 gmc sonoma sle ext-cab. hey it's a 4cyl. 5 spd and good on gas y'know?

03-25-2003, 08:09 PM	#10
bigvinnie Registered User Join Date: Aug 2001 Location: escondido, ca 92026 Posts: 1,222	bulkhead connector is where the harness plugs into the firewall, by the master cylinder... you need to follow your wiring back from the headlights and verify that there are no bare wires, and also that connections and grounds are solid... if the harness is original, you could have a brittle, exposed or corroded spot that would be hard to find... if you don't find anything obvious, best bet is to buy a new replacement headlight harness so you know your wiring is not the culprit... they're easy to install, not expensive, and might save you some time and headaches... __________________ '72 short step, 350, 700R4, tilt, ps, pdb, a/c, lowered coils, etc., other work in progress... San Diego, CA 72 Stepside Project Last edited by bigvinnie; 03-25-2003 at 08:15 PM.

03-25-2003, 09:44 PM	#11
krazy_texan Registered User Join Date: Oct 2002 Location: West Des Moines, Ia Posts: 3,233	check your harness __________________ Krazy Texan My Trucks are made with Wrenches not Chop Sticks 1967 GMC 3/4 ton "Johnny Cash" 1990 v1500 suburban 1967 Ford f100 Swb 4x4 "green bean" GOD BLESS JESUS, JOHN WAYNE, AND THE ALAMO

04-22-2003, 03:03 AM	#12
Jemost 72 Southern Bowties Join Date: Jan 2003 Location: Fort Worth, TX Posts: 240	Just an update for future reference: after replacement of 2 headlight switches, dimmer switch, both headlamps.. i may have found the problem. On the wires that go across the radiator, a couple of them were caught under the drivers side upper radiator support. I have been flash-free for 2 nights now. I'm keeping my fingers crossed that was the problem! __________________ 1972 Cheyenne 350/350



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