Headlight / Dash Light Help Needed

[ggerline]

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.

[ehjorten]

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.

[78BIG-TEN]

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

[bd]

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:

• Battery-to-engine (2 gauge)
  
  
• Battery-to-right frame rail (10 gauge)
  
  
• Battery-to-radiator support (10 gauge)
  
  
• Engine-to-left frame rail (an optional ground) (10 gauge or 5/16" braided copper strap)
  
  
• Cab firewall-to-back of right cylinder head (10 gauge or 5/16" braided copper strap)
  
  
• Dash cluster grounds-to-cab sheetmetal next to the parking brake pedal assembly (various gauges ranging 18 to 16 gauge)

In addition, if the battery cables are original, consider replacing them, now, with 2-gauge all copper cable.