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Day light running lights

Discussion in 'Chevy Trucks' started by MickiRig1, Jan 16, 2009.

  1. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    I know it's a Chevy Truck forum but I bet GM uses the same parts for this.
    I have a 2000 Malibu that has lost full power to the left headlights. They light but are just glowing. Using the light switch does not change it. I have checked the wires and connections. They are all OK. I wondered if anyone has had the Day Light Running Light control go out? The oldest son drives the car, he said they blinked out after hitting a bump.
     
  2. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    No high beam on the driver side either Micki?
     
  3. te snow

    te snow Member
    Messages: 46

    I have a friend with the same problem and after being at the dealer for a day they found that the other headlight (in your case the right side) was bad causing the problem. The dealer ended up changing both headlamp bulbs. If you have another headlight bulb on hand try changing the right side.
     
  4. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    The right side works normally. The left side just glows, the bulbs are working but not at full output. Both at low beam and high beam. It's not the bulbs, they are working just not putting out much light.I even used the stalk mounted headlight switch. No changes there, I just don't want to throw parts at it. It's been a great car till this point!
     
  5. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    If it's affecting BOTH low and high beams but only on the left side then I'd be checking the common input wires at the rear of the lights for 12V...which in your case would be the orange wires.

    This car (like the GM trucks of the same era) use a low side drive for head light operation...so the lights have 12V (on the orange wires) all the time...the auto headlight, DRL, and head light switch simply supplies the GROUND to illuminate the lights. And on that ground triggered side, all four lights are basically tied together through the BCM. But on the common input side they are separated LEFT AND RIGHT. Thats why you want to start with the common input wires.

    I can email you the diagrams for this head light system if you want them. Makes it much easier to follow/comprehend how the system operates.
     
  6. Woodland

    Woodland Senior Member
    Messages: 269

    You say the light is "glowing" which says to me that it is getting some power. I would start checking for a bad ground somewhere.
     
  7. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    Both the low beam and high beam bulbs just glow. They are getting power. I am going to change the oil in the car today and take another look at it.
     
  8. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    There is an old saying in Medical education : When hearing hoof beats think horses not zebras.
    In other words most times it's a common medical problem, nothing exotic like on the show HOUSE.
    I removed the wire loom looking for a broken wire, re-taped it again, I cleaned the bulbs and coated inside every connection with dielectric grease, I did the same to every ground on the whole car. Then I noticed that B&B said that the ground is the light function control on the system. I looked at the book again and noticed that the head light diagram was stuck to the page before it. DUH ! it has a 15 amp fuse for each side! Pulled the fuse, DUH it's blown ! FIXED ! Some times I scare myself.
     
  9. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    I even placed it in capital letters Micki. :D

    Good to hear its fixed. :waving:
     
  10. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    like my Wife says sometimes I just don't see the obvious. what threw me was the bulbs just glowing. It must have been feed back somehow? Some repairs just make you feel like you don' know all you do!
     
  11. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Yep, and it was from the other headlight through the DRL system...which is why knowing that your working with a low side driven light system matters at diagnosis time.



    Been there many many times Micki. :cry: :D
     
  12. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    Worst part is I have 3.5 years of electronic tech training! I should have went right to the basic's But NO,I am thinking it's something more advanced.