Marker light not working

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

ajwic1

Junior Member
Joined
Mar 3, 2024
Posts
11
Reaction score
3
Location
Nelson, BC, Canada
First Name
Alex
Truck Year
1981
Truck Model
c2500
Engine Size
5.7L v8 (350)
Hi there. 1981 c2500 pickup.
I have an issue with my drivers side marker light (facing outwards) that i cant seem to figure out.
When i turn left blinker on, the forward facing one flashes and the the side one DOESNT. (However the right side ones flash aswell!?!?). The rear work as they should.

Now in addition to that whenever i turn the headlights on (pull the knob out) the left front marker stays solid and once again side doesnt do anything. The dash also stays solid and so does the rear. And the right side stays lit also.
Right indicator functions as normal in both modes.

I have tried swapping them and confirmed the light is good. I used the test light pen and confirmed both sides of the connector has power. Multimeter was hard to get an accurate reading but it seemed low (less than 12v)

Has anyone experienced this/any ideas?
 

Jgonick

Full Access Member
Joined
Jan 12, 2017
Posts
328
Reaction score
422
Location
West Texas
First Name
Joel
Truck Year
1985
Truck Model
K10
Engine Size
350
First thing I would do is check your driver side front turn/park light (the one facing forward). Make sure it's not burnt out and it is the correct bulb. Also make sure the socket is grounded. That bulb has two filaments. The side marker lamp grounds through one of it's filaments.

The side marker lamps flow current in different directions depending if your park lights are on or off.
 

Attachments

  • 1_alternating_marker.jpg
    1_alternating_marker.jpg
    19.3 KB · Views: 51
  • 2_alternating_marker.jpg
    2_alternating_marker.jpg
    18.9 KB · Views: 43
  • 3_alternating_marker.jpg
    3_alternating_marker.jpg
    18.3 KB · Views: 45
Last edited:

Jgonick

Full Access Member
Joined
Jan 12, 2017
Posts
328
Reaction score
422
Location
West Texas
First Name
Joel
Truck Year
1985
Truck Model
K10
Engine Size
350
Just a side note. When the bulb with two filaments go bad (or it is not the correct bulb) it can cause a lot of strange problems. Especially when the two filaments are touching. If I remember correctly the bulb should be 1157
 

DoubleDingo

Full Access Member
Joined
Jul 3, 2012
Posts
11,331
Reaction score
17,393
Location
Right where I am
First Name
Bagoomba
Truck Year
1981
Truck Model
81-C20 Silverado Camper Special-TH400-4.10s
Engine Size
Carb'ed Vortec 350
And I think the side marker is 94? Any parts store should be able to get you the correct bulbs.
 
  • Like
Reactions: WFO

arborvitian

Junior Member
Joined
Nov 29, 2024
Posts
21
Reaction score
90
Location
Virginia
First Name
Long-Winded Loser
Truck Year
1974
Truck Model
C30
Engine Size
350
When I did the harness on my '74, I tried to go with LED all around. I ended up reverting to an 1157 and a? 194? for the front/side lights, because of the weird way they share ground. I don't remember the details, but the side marker light relies on some shared ground weirdness that's connected to the front turn/marker light. When it all works, they both flash when the turn signals or hazards are blinking. This ground trick only works with incandescent bulbs. I had LED bulbs originally, and I had to go buy some 1157s and 194s (I think) to get the front lights working correctly.

If you're having wacky issues in this area, the first place I would look is the grounds. There is one for each side. On a '74, they are on either side of the core support, and my original ones were sketchy. Probably similar for an '81, but I have no direct experience.
 

Latest posts

Forum statistics

Threads
44,426
Posts
957,679
Members
36,792
Latest member
mikeymch
Top