HELP Please - Headlight Problem

Discussion in 'Audio & Electronics' started by ascivious, Jan 7, 2017.

  1. ascivious

    ascivious Junior Member

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    2001 Ram 1500, Quadcab

    Have extremely dim headlights, both low and hi beam on an old truck. Hi beams are brighter than low beams, but still very dim.
    Started investigating and am thoroughly confused.
    Attached is a picture, with post call outs (A, B, C) for reference.

    With no bulbs installed here are the voltage measurements I get:
    (Passenger Side listed 1st)
    Off: A = 11.68V / 11.48V, B = 0V / 0V, C = 12.07V / 11.96V
    Lo Beams: A = 11.28V / 11.27V, B = .01V / .01V, C = 11.72V / 11.71V
    Hi Beams: A = .07V / .03V, B = 0V / 0V, C = 11.69V / 11.64V

    When I started trying to figure out dim lighting issue, 9004s were installed. Based on the voltage readings in the attachment, and my internet research, it appeared to me that 9007s should be installed.

    When the 9004s are installed the Passenger Hi Beam does not work, low beam does. Both hi and low work on Driver's side. Hi-beam indicator on instrument panel works as it is supposed to.

    With 9007s installed both low and hi beams work on both sides, however, the hi-beam indicator on the instrument panel will not extinguish in either setting.

    With either bulb, the lights are extremely dim. Not sure if I am dealing with multiple problems. All fuses appear to be good. I swapped light relay with a suitable and no change.

    Does anything look obvious? And which bulbs should be installed? Any help would be really appreciated.
     

    Attached Files:

  2. dudeman2009

    dudeman2009 Senior Member

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    You only have one headlight on either side? that means you have a non-sport model, and unless they changed it for the 00-01 years, the single headlights should have 9004s installed.

    When you are making voltage measurements you are using a known good ground? such as the engine, battery terminal or frame/body?

    Just a little mistake, but you got the pinouts labeled backwards. No harm, just understand that wiring diagrams will be backwards. You simply swapped pins A and C.

    Pin A is connected to battery positive. That should always read battery voltage, or close to it. That seems to be the case if the vehicle wasn't running.

    Pin C is for the high beams, when the lights are off or in low beam mode, it should be floating at near battery voltage and the dash light should be out. Pin B should be floating around zero volts when the lights are off or when the high beams are on.

    To test, you can do a few things. You can use a test lamp, or a multimeter with a continuity setting. let me know if you'd like to test it or try replacing the headlamp switch.

    One possibility is that your headlamp switch is bad, that's pretty common on these trucks.
     
  3. ascivious

    ascivious Junior Member

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    Dudeman2009,

    Yes, only one headlight each side. For ground, used negative battery terminal. For the wiring diagram, I had difficulty making much sense of it, so those labels were my own without reference to diagrams. All measured voltages I posted were with engine off.

    What test actions do you recommend? Is there a way to test the headlamp switch? Either way, do you think that could be causing the dim lighting problem?

    thanks for your help
     
  4. chopperman1

    chopperman1 Senior Member

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    What's the battery voltage? All are a bit low but could be normal based on battery voltage.

    Battery voltage off = ?
    Battery voltage running = ?

    Could be a charging/battery issue.
     
  5. dudeman2009

    dudeman2009 Senior Member

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    As chopper said, you did check to make sure it is charging properly? I just assumed you did, because thats what i'd do. But we all know what assumptions make.

    You're not alone on the wiring diagrams, the front lighting is a weird positive ground setup, that gets a lot of people.

    As for testing, there are two options, you can get a test lamp that will draw about 50W or you can use the stock 9004 bulbs and a multimeter.

    If you go the test lamp route, you will need to do three tests twice. First, hook one end to battery negative and probe pin A this is the battery source, it should light brightly. For the next two, hook one end of the probe to battery positive. With the lights on the low beam mode, probe pin B this is you low beam ground, the bulb should light brightly. Next with one end of the probe on battery positive, turn on the high beams and probe pin C this is your high beam pin, it should light brightly.

    Repeat all tests on the other side. If one side is fine and the other isn't the issue is with the wiring between the two. If the problem is on both sides on Pin A, you have a supply issue. If its on both sides on pins B or C, you may very well be looking at a headlamp switch.

    To use a multimeter, set it to read voltage. Plug in one bulb and turn on the low beams. Probe on the empty connector from battery positive to Pin A, you should see less than .6V. Next probe from battery negative to pin B, you should see less than 1V. Turn on the high beams and probe from battery negative to pin C, you should see less than 1V.

    Repeat the test by swapping the side the bulb is in. I'll need to see the results from the multimeter test in order to interpret them as its too much to type out. The test with the multimeter is more telling, but you cant go wrong with the test lamp either.
     
  6. ascivious

    ascivious Junior Member

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    Chopperman,

    Voltage at battery with engine off is 11.88. Voltage with engine on is 14.3. Same 14.3 with all lights on and engine running.
     
  7. dudeman2009

    dudeman2009 Senior Member

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    Your alternator is working fine then. The battery might be a little weak, but if it starts the truck, no worries there. A weak battery will only affect headlight brightness when the truck isn't running.
     
    Last edited: Jan 11, 2017
  8. chopperman1

    chopperman1 Senior Member

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    Sure sounds to me like the battery itself is bad. Do you have an autozone/pepboys etc around you? Bring the battery in to them and have them do a free load test on it for you. Charging system seems fine based on voltage under load.
     

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