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73-87 Chevy _ GMC Trucks => Electrical => Topic started by: ggerline on October 28, 2014, 01:37:24 pm

Title: Headlight / Dash Light Help Needed
Post by: ggerline on October 28, 2014, 01:37:24 pm
Hi all, new member and first post. I have a 79' C10. Just upgraded the headlights recently to a LED Headlights (Round Headlights). After doing this, when I try to turn on my dash lights using the dimmer switch, the headlights will not change from High to Low or vice versa. If I turn the dash lights all the way off using the dimmer switch, I can cycle through the headlight modes, but no dash lights. I purchased a relay after this hoping it would fix the issue, allowing the headlights to run directly off the battery and not the headlight switch. Just trying to be able to turn up the dash lights on the dimmer switch so I can see my gauges and also cycle headlights from low to high / high to low like normal. Any help/ideas would be very much appreciated.
Title: Re: Headlight / Dash Light Help Needed
Post by: ehjorten on October 28, 2014, 02:12:54 pm
No relay is needed!  These LED headlamps draw less current than the original design.  I have the GE Nighthawk 7" rounds in my '77.  They are a simple plug-n-play!  I did recently have to replace my headlamp switch though because I had similar issues.  The rheostat for the dash lights was shot.
Title: Re: Headlight / Dash Light Help Needed
Post by: 78BIG-TEN on October 30, 2014, 12:10:44 pm
Thought the dash lights were actually part of the park\taillight circuit and headlights a different circuit of their own working through dimmer switchThat being said on the old style lamps a common upgrade was to run direct battery power with a heavy wire gauge through a couple of relays to give less voltage drop thus brighter light.I've never checked for drop at the lamp cause I'm happy with what I have
Title: Re: Headlight / Dash Light Help Needed
Post by: bd on October 30, 2014, 06:39:05 pm
Quote from: ggerline on October 28, 2014, 01:37:24 pm
Hi all, new member and first post. I have a 79' C10. Just upgraded the headlights recently to a LED Headlights (Round Headlights). After doing this, when I try to turn on my dash lights using the dimmer switch, the headlights will not change from High to Low or vice versa. If I turn the dash lights all the way off using the dimmer switch, I can cycle through the headlight modes, but no dash lights. I purchased a relay after this hoping it would fix the issue, allowing the headlights to run directly off the battery and not the headlight switch. Just trying to be able to turn up the dash lights on the dimmer switch so I can see my gauges and also cycle headlights from low to high / high to low like normal. Any help/ideas would be very much appreciated.

Welcome to the site!

There could be a floating ground (a shared ground connection that isn't actually making good electrical connection to battery negative).  Verify that all of the following grounds exist and are making good electrical connection by taking the connections apart and sanding to bare shiny metal - recommended cable sizes are in parentheses.  When you're done cleaning, coat the connections with anti-oxidant as you assemble them:
In addition, if the battery cables are original, consider replacing them, now, with 2-gauge all copper cable.