When you try to switch to the high beams the little blue light appears on the dash, but no lights?

Tiny
MISTERCJ
  • MEMBER
  • 2010 CHEVROLET SILVERADO
  • 6.0L
  • V8
  • 4WD
  • AUTOMATIC
  • 127,000 MILES
My Low beams work and function as they should, when you try to flip to high beam little blue light appears on dash, but no lights. The fuse cluster is brand new. I spent the last couple of hours with a test light testing every port and think I found the culprit. There is a white and blue/purple(?) Wire leading out of each headlight assembly. The one from the pass side heads over to the driver's side. I believe this is ground... Maybe? Can you confirm? Would a bad ground be causing these symptoms? Where does this actually ground out at? I Did some searching and couldn’t see it. Also, this truck has a Boss snowplow and has the snowplow relays. All of these relays are brand new, so I don’t believe one of those is causing this.
Monday, September 26th, 2022 AT 7:30 AM

6 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,144 POSTS
It sounds like you have a High Beam PCB relay that is not working which is non serviceable, please check all fuses in the PDC. Here is the headlight and high beam wiring diagrams so you can see how the system works and the relay location as well in the images below. Check out the images (below). Please let us know what you find. We are interested to see what it is. The ground wires for the headlights are black.
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Monday, September 26th, 2022 AT 10:59 AM
Tiny
MISTERCJ
  • MEMBER
  • 4 POSTS
Hi Ken,

In my Silverado, the low beams and high beams are on the same relay (like in your image). My low beams are good, and the relays were replaced when I got the new fuse cluster. When I pull the harnesses apart behind the headlight assembly, I have a plug with eight plugs. It seems like four are for low beams/DRL (two hot, two ground), two are inactive and two are for high beams. The ground is white and blue, which I don’t see in your diagrams. Can you confirm if this is the ground cable, and if so, where does it ground out to?
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Monday, September 26th, 2022 AT 11:07 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,144 POSTS
I don't see any white and blue wires in the diagrams can you upload an image or a short video of what you are seeing? Do you have aftermarket LED's or?
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Monday, September 26th, 2022 AT 5:33 PM
Tiny
MISTERCJ
  • MEMBER
  • 4 POSTS
I figured out that it was not part of the high beam lights. I still haven’t found the problem through. I have power at the fuse cluster, but no power at the high beam plugs. Both sides, Dr and pax. What might it be?
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Monday, September 26th, 2022 AT 7:12 PM
Tiny
MISTERCJ
  • MEMBER
  • 4 POSTS
So, I have power at the fuses (R and L high beam), I have power at the low/high beam relay, but no power at the actual connection points for the headlights. Is there a point where the high beam wires come together? At the ground? Or might the multifunction be bad? I do have the blue icon when I switch the bights to where they are supposed to be on.
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Tuesday, September 27th, 2022 AT 9:58 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
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When you say you have 8 lugs at the headlight do you mean the switch or the headlight itself?
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Thursday, September 29th, 2022 AT 12:47 PM

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