| Low beams intermittent [message #305493] |
Tue, 16 August 2016 23:11  |
pzerkel
Messages: 212
Registered: September 2007
Location: Salisbury, IL
Karma: 0
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Went for a test drive tonight after dark, and after replacing a wheel cylinder and bleeding brakes. When I first started I only had one light when on low beams. I jiggled the connector and headlight came on. The high beams worked fine.
Drove to gas station, about 6 miles. low and ho beams both worked, both sides. Filled up with gas, and drove home. On the drive home I had high beams, but when I dimmed them now both headlights went out. Thankfully not much traffic on the route so I only annoyed a few other drivers with constant high beams. My wife was following and I was told my taillight/brake lights/turn signals, etc. were all working fine.
Is the best first step to replace the headlight connectors? If so how big a job is that? Any special tools needed?
Thanks
Paul Zerkel
'78 Eleganza II
Salisbury IL (near Springfield)
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| Re: Low beams intermittent [message #305501 is a reply to message #305493] |
Wed, 17 August 2016 00:00  |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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No harder to replace then a car of the 70's. I would unplug the socket and clean the connections in the socket and the headlights also make sure there are no loose wires
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: Low beams intermittent [message #305505 is a reply to message #305501] |
Wed, 17 August 2016 01:05 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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In a previous life when I use to service large computers for IBM, one of the tools I carried was a burnishing blade. It was used to polish relay contacts. I do not know where to get one but you could make one out of a paper/cardboard fingernail file. Get a set of 6 or so at Walmart for $1.00 or 2.00 and cut one with a pair of scissors to the width of the inside of the contact socket. Slide it in and out a few times to clean / polish the contact surface. Also polish the blade type contact on the bulb. If that does not work then remove the contacts from the bulb socket and squeeze them slightly to increase the tension on the contacts.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Low beams intermittent [message #305509 is a reply to message #305493] |
Wed, 17 August 2016 06:09 |
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RF_Burns
Messages: 2277
Registered: June 2008
Location: S. Ontario, Canada
Karma: 3
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It could also be the connector at the hi/low beam switch or the switch itself at your foot. The factyou said both lows did not come on when switching from hi to low would lead me to checking this first. as that is the common power point for both beams.
Pull ON the lights this morning without touching anything and see if the low beams are still not working. If they are still out, then great , you can use your volt meter to troubleshoot the problem. You should see power on two of the three wires at the switch. They are the power from the light switch and the power going to the low beam. If you see power on only one wire, then I would clean the connector first. Failing that, replace the switch.
If you see power on two wires, then you know the issue is not with your hi/low switch and your issue is likely to be the connectors at the lights. In either case, cleaning all the connectors is a good idea since they are subject to corrosion after all these years.
New connector pigtails are available as well since the connectors are subject to fatigue and may never make a good connection.
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
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| Re: Low beams intermittent [message #305510 is a reply to message #305493] |
Wed, 17 August 2016 06:56 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Besides all of the above truisms, the GMC used a 3 pin headlight connector with more of a protective "splash cup" molded in. When I went to Sylvania Silverstars the molding style of the glass prevented full contact insertion. I had to trim a bit of plastic away. I have not seen this style of connector on any other GM car. BTW the connection at the floor dimmer fools a lot of "experts".
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Low beams intermittent [message #305520 is a reply to message #305510] |
Wed, 17 August 2016 10:42 |
Bullitthead
Messages: 1411
Registered: November 2013
Karma: 5
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Same problem as John...that plastic cup made into the headlight connector had to be trimmed to get the electrical connections far enough on to the male spade terminals on the bulb. If your bulbs have been replaced, check the fit carefully to see if this is your problem source.
Terry Kelpien
ASE Master Technician
73 Glacier 260
Smithfield, Va.
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| Re: Low beams intermittent [message #305531 is a reply to message #305493] |
Wed, 17 August 2016 16:50 |
captjack
Messages: 271
Registered: February 2010
Location: Sebastopol, California
Karma: 1
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I'd suggest and alternative that replaces the sockets with better ones and gives you brighter lights. Currently all the current flows through the headlight switch on the dash. I noticed that my headlights were dim compared to my other cars, bought new lamps with no difference. On the suggestion of another GMC owner, I purchased a kit (lots of versions on-line) which provides new sockets and powers the lights with relays directly (fused) from the battery. After hooking it up, my lights are much brighter. It took a couple of hours to hookup. Here's an example that seems to meet all the requirements and costs $18. There are others.
http://www.ebay.com/itm/2-Headlight-H4-Headlamp-Light-Bulb-Ceramic-Socket-Plugs-Relay-Wiring-Harness-Kit-/262483542712
Jack Christensen - K6ROW,
'76 Glenbrook/Clasco - "The Silver Bullet",
Sebastopol, CA
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| Re: Low beams intermittent [message #305904 is a reply to message #305510] |
Tue, 23 August 2016 20:02 |
pzerkel
Messages: 212
Registered: September 2007
Location: Salisbury, IL
Karma: 0
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What is a good tool to use to trim this "splash cup" away? Seems even the non-SilverStar Sylvanias are now molded where they interfere.
JohnL455 wrote on Wed, 17 August 2016 06:56Besides all of the above truisms, the GMC used a 3 pin headlight connector with more of a protective "splash cup" molded in. When I went to Sylvania Silverstars the molding style of the glass prevented full contact insertion. I had to trim a bit of plastic away. I have not seen this style of connector on any other GM car. BTW the connection at the floor dimmer fools a lot of "experts".
Paul Zerkel
'78 Eleganza II
Salisbury IL (near Springfield)
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| Re: [GMCnet] Low beams intermittent [message #305912 is a reply to message #305904] |
Tue, 23 August 2016 23:17 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Paul,
Take a shier or a razor blade and trim off 1/8 - 1/4 inch off all around.
On Tue, Aug 23, 2016 at 6:02 PM, Paul Zerkel wrote:
> What is a good tool to use to trim this "splash cup" away? Seems even the
> non-SilverStar Sylvanias are now molded where they interfere.
>
>
> JohnL455 wrote on Wed, 17 August 2016 06:56
>> Besides all of the above truisms, the GMC used a 3 pin headlight
> connector with more of a protective "splash cup" molded in. When I went to
>> Sylvania Silverstars the molding style of the glass prevented full
> contact insertion. I had to trim a bit of plastic away. I have not seen this
>> style of connector on any other GM car. BTW the connection at the floor
> dimmer fools a lot of "experts".
>
>
> --
> Paul Zerkel
> '78 Eleganza II
> Salisbury IL (near Springfield)
>
> _______________________________________________
> GMCnet mailing list
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--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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