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

Dim Headlites?

Discussion in 'Ford Trucks' started by peterk800xc, Dec 7, 2011.

  1. peterk800xc

    peterk800xc Senior Member
    Messages: 188

    I found a problem tonite on my 2002 Ford F-350 SD Diesel.With the engine running, my headlites on the truck and also Plow lites are dim.I just replaced both batteries a month ago with 850 amp ones so its not the batteries. Now the funny thing is when I shut the truck off, the headlites brighten up immensly! Can the alternator be going bad? Thanks in advance for any help.
     
  2. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    Check your grounds on the harness. Clean and put Dielectric grease on them to protect them. Pull every black wire bolted to the engine or body and clean and protect with Dielectric grease. Bad connections / grounds will feed back thru stuff and cause weird stuff to happen! Make sure you have a good ground connection to the hydraulic plow pump too. It the connection is poor it takes longer to move the plow. Hense more amp flow, more charging system stress.
     
  3. mnglocker

    mnglocker Senior Member
    Messages: 923

    MickiRig gave you a good starting point. Clean all your grounds and connectors, use dielectric grease when you put them back together.
     
  4. mikegooseman

    mikegooseman Senior Member
    Messages: 123

    .

    Agreed... clean the terminals etc, but it sounds like the alternator is on its way out.JMO
    Good luck
     
  5. peterk800xc

    peterk800xc Senior Member
    Messages: 188

    Truck lites have been dim for awhile to

    I don't think its in the plow circuit as the plow was just put on a few weeks ago.The truck lights wer dim for sometime before I put the plow on it from my older truck.In fact I had replaced both headlight bulbs when I got the truck with the Sylvania super bright bulbs because they were kind of dim.These bulbs were not any brighter than the original ones.The truck has just turned 100000 miles on it and it has the original alternator so I think I will probably just put another on it today.Thanks guys!
     
  6. mnglocker

    mnglocker Senior Member
    Messages: 923

    Don't skip fix'n up your grounds.
     
  7. Too Stroked

    Too Stroked Senior Member
    Messages: 555

    After cleaning & greasing all of your grounds, get out a DVM and see what kind of voltage the system is running at. Remember, while your truck is running, the alternator is more important than the battery.
     
  8. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    Most Ford trucks I have worked on have the light circuits grounds attached to the core support. Get them shiny clean with sand paper.Protect with dielectric grease.
    Look real close for ground connections. There can be a bunch of them. Don't forget the most important one. The ground cable from the battery bolted to the engine block. Look at the terminal ends on the battery cables. Could be hidden crude inside the cables.You can buy new pig tails for the head light plugs too. They may be gone too. Another place people forget the Dielectric grease protection.
     
  9. peterk800xc

    peterk800xc Senior Member
    Messages: 188

    Thanks!

    Cleaned the grounds and cable ends ( not to bad) stopped at AutoZone and they checked the charging system 11.5 volts running at idle.They didnt have an alternator in stock but 1 will be here on Saturday.Thanks again for the help,
     
  10. MickiRig1

    MickiRig1 PlowSite Veteran
    Messages: 3,617

    Another few bit's O wisdom: Buy a digital Volt Ohm Meter (VOM). Much better for measuring voltages when you are testing stuff. There are check out procedures for no starts, ignition / emission components and charging systems. In most repair manuals. That's why you need the digital VOM. A static not running battery should be at 12.6 volts. Running and charging it will be at 14.5 volts. With everything on, lights, wipers, heat blower fan it should be no lower then 13.5 volts. When your plowing and the volt gage starts to drop under 12 volts your running away from your charging. It's not keeping up. Your now running off your batteries. Not good! Computer needs a certain voltage to work. You drop below it. The pump on the plow is triggered and the truck dies! Charging is a big issue on the site. Search charging and you may find days of reading.
     
  11. mnglocker

    mnglocker Senior Member
    Messages: 923

    Using the DVOM YOu can also check each wire for voltage drop. (A sign of a bad cable, crappy ground, or a ground where their shouldn't be one)

    Set to DC-Voltage place a test lead on each end of the wire with the circuit powered up. If you read more than 0.10VDC; clean the ends, check for cracked insulation and corrosion inside the wire. Or just replace the wire and play it safe.
     
  12. mnglocker

    mnglocker Senior Member
    Messages: 923

    More wisdom... Don't get too cheap with your DVOM, Meterman, Fluke and Gardner Bender come to mind for some decent names off the top of my head. The trick is to get one that has a high RMS Sampling Rate, so that it can actually "see" the undulations in the current.
     
  13. peterk800xc

    peterk800xc Senior Member
    Messages: 188

    Fixed- Thank you

    Thanks for the help on this.New alternator and charging at 14 volts and lights brightened right up. Very easy to change the alternator on my Ford-unlike another brand!!!!!!!