Front turn signals and marker lights?

Tiny
THEBENTWAN
  • MEMBER
  • 1984 CHEVROLET 2500
  • 5.7L
  • V8
  • 4WD
  • MANUAL
  • 257,000 MILES
I have replaced the front grill assembly and changed the wiring harness to run to different headlight types and configuration to side by side.
The replacement harness is a used one with some damage to the passenger set of turn signals and headlight socket, and I wired them up as well. The headlights worked instantly, dims and brights, but the turn signals up fron will not work, however the real brakes and signals work fine. I've checked the fuses all through, and replaced several, but turn/ BU fuse is fine. I am now tracing the lines from the column to the fuse box, and every thing is clean, no damage.
And im curious, if I have continuity at the bulb socket. Doesn't that mean the circuit is going all the way through, or?
Sunday, April 26th, 2026 AT 7:43 AM

1 Reply

Tiny
STEVE W.
  • MECHANIC
  • 15,706 POSTS
Attached are the front wiring for both light styles. GM used the same wiring colors so those shouldn't be the issue unless the wiring was damaged. I would take a test light and pull the front marker light bulbs as well as the side markers. Connect the test light to battery negative. With the switch on marker position you should have power on the brown wires at the side and front markers. Move the test light to the positive post and the light should light when you probe the Dark and Light Blue wires at the marker light sockets and the black wires as well. The Black wires are the main grounds. If those all check out, connect the test light back to ground and now switch on the 4 way lamps. Now you should get a pulsing power feed to the outer marker lights on the Light and Dark blue wires. At the front marker turn you should also have the pulsing feed in the same wires. These lights work by using the bulbs themselves as a ground path as well. So if you replaced the halogen bulbs with LED they may not work properly as those will not operate that way.
Try the tests and see what you have.
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Sunday, April 26th, 2026 AT 12:11 PM

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