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headlights dimmer than they should be need help

Discussion in 'Peterbilt Forum' started by heuchert, Mar 13, 2014.

Page 1 of 2
  1. Mar 13, 2014 #1
    heuchert

    heuchert Bobtail Member

    7
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    Dec 18, 2013
    Alexnadria, MN
    0
    I have a 1999 pete 379 it has the 7" single headlights. My high beams are as bright as my dims should be and my dims barely light up. I went and bought the xeon hid lights and also checked the ground and cleaned it up and there was no change. What else could be causing this?
     
    heuchert, Mar 13, 2014
    heuchert, Mar 13, 2014
    #1
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  3. Mar 13, 2014 #2
    Flightline

    Flightline Road Train Member

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    Oct 1, 2011
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    Strange I had the exact set up.
    Headlight aiming helps little but didn't make enough difference for me.
    Was told lousy ground would make all the difference but apprently I didn't have lousy ground.
    Finally got me a pair of the 4"x5" double square headlights like wing style from the junk yard and twice as good.
    Sold the round ones on ebay for almost as much as I paid for the used 4 light style.
     
    Flightline, Mar 13, 2014
    Flightline, Mar 13, 2014
    #2
  4. Mar 13, 2014 #3
    Flightline

    Flightline Road Train Member

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    Also seen where one could buy true LED headlights and 7 times brighter.

    But hard to justify at such a high cost of $600 a bulb.
     
    Flightline, Mar 13, 2014
    Flightline, Mar 13, 2014
    #3
  5. Mar 13, 2014 #4
    heuchert

    heuchert Bobtail Member

    7
    0
    Dec 18, 2013
    Alexnadria, MN
    0
    My cousin has the same headlights on his 04 379 and his work even better than the double squares. The only thing he says to check is see if there is a voltage regulator for them or maybe broken wires. I plan on checking all the wiring over the weekend when I get home to see if that's the issue
     
    heuchert, Mar 13, 2014
    heuchert, Mar 13, 2014
    #4
  7. Mar 14, 2014 #5
    Excorcist1

    Excorcist1 Light Load Member

    222
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    Jan 11, 2012
    Chestertown, MD
    0
    I have a different model but had the same issue. You can have a broken ground wire on either side and your lights will still work but won't be as bright. Make a long story story short check the wiring where your headlight harness's plug into the main harness. After replacing sockets on both sides I later found out it was the main harness rubbing against the frame under the front.Wiring broke right at plug just enough to get power but barely touching.
     
    Excorcist1, Mar 14, 2014
    Excorcist1, Mar 14, 2014
    #5
  8. Mar 15, 2014 #6
    heuchert

    heuchert Bobtail Member

    7
    0
    Dec 18, 2013
    Alexnadria, MN
    0
    that would make sense because for a while I would be driving and they would go from being so dim to having some brightness then back to dim and I noticed when they would go really dim my high beam light on the dash would slightly illuminate when the bright lights weren't on
     
    heuchert, Mar 15, 2014
    heuchert, Mar 15, 2014
    #6
  9. Mar 15, 2014 #7
    CondoCruiser

    CondoCruiser The Legend

    19,726
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    Apr 18, 2010
    Tennessee
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    Besides what others say check your alternator output. It's possibly getting weak. It should be up near 14.5V.

    If that's not it then check your headlight ground. It'll be up near the passenger headlight somewhere close. It could be corroded.
     
    CondoCruiser, Mar 15, 2014
    CondoCruiser, Mar 15, 2014
    #7
  10. Mar 15, 2014 #8
    heuchert

    heuchert Bobtail Member

    7
    0
    Dec 18, 2013
    Alexnadria, MN
    0
    my alternator is running a bit above 14 on the gauge. I looked at the connectors they all look good but on the right side (passenger side) I did see that there is a small ground wire running to a tech screw that is in the radiator mount with another wire that runs to the frame right up front and is grounded there. I cleaned that up and no change. I'm still lost on what it all could be
     
    heuchert, Mar 15, 2014
    heuchert, Mar 15, 2014
    #8
  11. Mar 16, 2014 #9
    CondoCruiser

    CondoCruiser The Legend

    19,726
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    Apr 18, 2010
    Tennessee
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    Did you remove the ground wire and clean under it. That's where it gets corrosion. You can't see it otherwise.

    Now is this all taking place after you installed the HIDs?

    Your high beams and low beams are two separate circuits with each having their own relay. They do share a battery feed and a chassis ground which I think you found. Check your voltage at the low beam socket, check your voltage on pin 30 at your low beam relay. Use chassis ground for your negative probe and not some ground wire. See if there is a drop between the two readings.
     
    CondoCruiser, Mar 16, 2014
    CondoCruiser, Mar 16, 2014
    #9
  12. Mar 16, 2014 #10
    Excorcist1

    Excorcist1 Light Load Member

    222
    39
    Jan 11, 2012
    Chestertown, MD
    0
    Exactly you probally won't see it. I would hit a bump and the right side would go out. I'd go to replace the bulb but it would light up then the left side would go out. Sockets would melt and I replaced them. etc, etc Had proper voltage reading on gage, good grounds but that 1 power wire on the right side arcing cause havock.
     
    Excorcist1, Mar 16, 2014
    Excorcist1, Mar 16, 2014
    #10
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