1. Welcome to PlowSite. Notice a fresh look and new features? It’s now easier to share photos and videos, find popular topics fast, and enjoy expanded user profiles. If you have any questions, click HELP at the top or bottom of any page, or send an email to help@plowsite.com. We welcome your feedback.

    Dismiss Notice

Headlights not working

Discussion in 'Boss Plows Discussion' started by ohiogreenworks, Dec 30, 2009.

  1. ohiogreenworks

    ohiogreenworks Senior Member
    Messages: 381

    Alright just my head lights are not working. 8.2 v rt3. Everything else works great. The headlights went out the other night. What do I check and where do I start checking? I searched and found a million threads and everyone seems to have a different answer. I just need a simple list of what to start checking....:realmad:
     
  2. grandview

    grandview PlowSite Fanatic
    Messages: 14,609

    Did you flip the switch?
     
  3. ohiogreenworks

    ohiogreenworks Senior Member
    Messages: 381

    YES I FLIPPED THE GD SWITCH. They just went out as I was driving down the road.
     
  4. Gumpy52

    Gumpy52 Member
    Messages: 70

    If your truck lights work but not the plow lights, check the wires at the battery, the small red and bown wire may have coroded at the terminals.
     
  5. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Nice attitude for free help. :rolleyes:

    Don't bother with the brown and red on the battery as that's not whats wrong...
     
  6. grandview

    grandview PlowSite Fanatic
    Messages: 14,609

    ....................
     
  7. ohiogreenworks

    ohiogreenworks Senior Member
    Messages: 381

    Sorry I was a little agitated and def very very low on sleep, didn't mean to have an attitude.

    I messed with the switch in the truck and took it apart to make sure the wires were still connected and they were. I followed the two wires that go into it all the way up front to the relays I think. I am not for sure where the two wires go when they get up in the engine bay, it is hard to tell which ones are which.

    I guess my biggest question is what can/would make just the headlights not work. Everything else works as it is supposed to? Aside from both bulbs burning out at the same time....

    I appreciate the help, I'll try to not let the headlights not working get to me and have an attitude....:eek:
     
  8. pyro29

    pyro29 Member
    Messages: 38

    I assume that the truck lights still work and that when you toggle the switch the truck side lights will come on and off, correct?

    Do the park and turn signals still work on the plow?

    Post results...
     
  9. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Yes we all get a little cranky at times when things aren't working as intended, been there many times myself. Now, for the issue at hand...

    1) Disconnect the two black wire leads at the truck/plow rocker switch and connect them together with a jumper wire. Turn the ignition on. Do the plow lamps now work> If so then the rocker switch is defective.

    2) Use a test light and check each brown wire on each of the relays for a good ground. Should have it.

    3) Same test light procedure but check the black wires for 12V with the ignition on, there's one at each relay and they should all have 12V when the rocker switch is in the "plow" position.

    4) Pull each relay out and check for any corrosion on the terminals and sockets.


    Should get you covered for the basics...
     
  10. ohiogreenworks

    ohiogreenworks Senior Member
    Messages: 381

    Yes you are correct the truck side works then flip the switch and no headlights. The parking lights on the plow work. The driver side turn signal blinks, the passenger side hasn't blinked all year. It lights up just doesn't blink. I didn't have time to fix it and I wasn't too worried about just the turn signal since everything else did work lol


    Thank you. I will work on it tomorrow and post my findings.
     
  11. ohiogreenworks

    ohiogreenworks Senior Member
    Messages: 381

    Well update time.

    I took the wires off the switch and wired them together. Still no lights,

    I also turned the truck on and flipped the switch to truck. When I pulled the far left relay out the lights on the truck go off. Does that mean the relay is working or not? I assume it is still working since when I put it back in the truck lights come back on. If that makes any sense, not sure lol.

    Any ideas?
     
  12. ohiogreenworks

    ohiogreenworks Senior Member
    Messages: 381

    I looked at a wiring diagram and I see that there are two headlight adapters. Where do they plug in on the truck, 2002 GMC 2500hd. I think the adapters could be my problem, just not sure where they are or what they hook up or what they even look like! :p
     
  13. ohiogreenworks

    ohiogreenworks Senior Member
    Messages: 381

    Ok found the adapters eveything appears to be plugged in and in good shape.

    I still have the toggle switch in the truck un hooked. When I touch the wires together the far left relay of the 4 clicks. It is the only one that clicks. Do I just need a relay??
     
  14. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Actually three of the four relays should click when you flip the switch to the plow light position because the same three relays are all needed for the lamps to switch over to the plow. The outside one is the high beams, the next one over is the common and the third one in is the low beams.

    Get the test light out....

    1) Check the black wire on all three of those relays for battery voltage with the switch in the plow lamp position and the ignition on. Should have battery voltage on all three.

    2) Check the brown wire on each relay for GROUND. Should have it.


    Also assuming here you have no low OR high beams correct?
     
  15. ohiogreenworks

    ohiogreenworks Senior Member
    Messages: 381

    B&B,

    I appreciate your help. I think the only one clicking the the one closest to the engine. When I pulled it out, the clicking stopped. I do not have either low or high beams btw. Got a test light, just the light tho no voltage meter but I'm gonna go check it out. Thanks
     
  16. ohiogreenworks

    ohiogreenworks Senior Member
    Messages: 381

    Alright,

    Got my test light on and all the relays pulled out. Looking from the front of the truck. I have power at the red wire on the far left relay and the white wire on the 2nd from right relay.

    With the relays all plugged in. I have power on the black, red, and red/black wires on the far left relay. I only have power on the blue and white wires on the far right and 2nd from right relays. Nothing on the 2nd from left relay at all. The far right and the 2nd from right relays also have no power on anything except for the white wire and blue wire.

    Now with the wires coming into the cab twisted together I have the following. Same with relay on far left. 2nd from left nothing. 2nd from right power to white and white/yellow. Far right no power on blue anymore.

    Confused :dizzy:
     
  17. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    If you don't have power on ALL of the black wires, or ground on ALL of the brown wires the relays won't work regardless of what all other wire have or do not have power.

    If you look closely you'll see where the single black wire exits from the loom on its way to the relays and terminates in a pin on the second relay from the left. From there its simply daisy chained over to the other relays. That wire should have battery voltage with the key on and your light switch wires connected together. Does it?

    How about one of the two wires at the switch? Have you checked it to see if it has batt voltage yet? One of the two should.
     
  18. ohiogreenworks

    ohiogreenworks Senior Member
    Messages: 381

    I do have power on that first black wire on that 2nd relay. Must have missed that before.

    I also have power in the cab on the wire that was the one plugged into the truck side of the rocker switch.
     
  19. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Then all the black jumpers between each relay from that black wire should have power too.

    Did you check all the browns for good ground at each relay as well? Sometimes they look black too but are actually dark brown. They all need to show a good ground.
     
  20. ohiogreenworks

    ohiogreenworks Senior Member
    Messages: 381

    It didn't seem like they all had power....hmmm gonna have to check it tomorrow, too dark out in the road now lol. Can I check for a ground with just a test light? If I just reverse what I am doing with the light now? Anyways, thanks for your help :drinkup: