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  1. #1
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    Real car help! Headlights dimming...

    Parents gave us a 2007 Hyundai Entourage minivan and it drives well but whenever you slow down (let off gas _or_ brake) the headlights dim very noticeably.

    Haven't had it long enough to try any troubleshooting yet. Haven't worked on full size cars much. Thought I'd ask the forum members for advice first.

    Let me know what u think.

    Thanx...
    What broke, uh, needs upgrading now?

  2. #2
    RC Turnbuckle Jr. icepick832's Avatar
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    Check the age of the battery, and have the alternator tested. If the battery is to old it may need to be replaced.

  3. #3
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
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    Quote Originally Posted by icepick832 View Post
    Check the age of the battery, and have the alternator tested. If the battery is to old it may need to be replaced.
    Yes... older batteries will do this.
    Whatever it is I just said... I could be wrong.

  4. #4
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    I'll take it over to autozone and have the battery and alternator tested. Can they test the voltage regulator too or is that necessary?
    What broke, uh, needs upgrading now?

  5. #5
    Marshal Double G's Avatar
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    They should but typically the regulator is inside the alternator.
    The Super Derecho

  6. #6
    RC Turnbuckle Jr. icepick832's Avatar
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    Yeah, not many vehicles (not that I know them all) have separate voltage regulators now a days.

  7. #7
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    Well, I'll be heading to autozone soon. Also need to pick up fuses. Blew the 7.5A ACC fuse while installing new stereo on same vehicle. Hope that fuse prevented frying new stereo...!
    What broke, uh, needs upgrading now?

  8. #8
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    Tester at Autozone showed battery and alternator are just fine... The mystery deepens!

    Any advice or ideas would be greatly appreciated.
    What broke, uh, needs upgrading now?

  9. #9
    RC Turnbuckle Jr. Jimmie Neutron's Avatar
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    When you let off the gas, the alternator is no longer spinning up fast enough to produce a higher voltage... resulting in a voltage dip. If the battery is under-rated for the car or nearing the end of its life, you will see a difference in brightness of the headlights.

    How much of a difference is there?

    To some degree, this 100% normal... and chasing down a problem that really isn't there can be quite costly.


    On another note, I have had batteries tested by places like Autozone die within days of them claiming it is OK.
    Whatever it is I just said... I could be wrong.

  10. #10
    Marshal ksb51rl's Avatar
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    Quote Originally Posted by Jimmie Neutron View Post
    ...On another note, I have had batteries tested by places like Autozone die within days of them claiming it is OK.
    I have as well, just this past year.
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  11. #11
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    Get hids bulbs. They use less power so they wont dim
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  12. #12
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    Well, it sure wouldn't hurt to try a new battery, at least not more than around $100...

    Batteriesplus website lists the replacement for this 2007 Hyundai Entourage as a 500 CCA battery, while Autozone lists a different battery for the same vehicle with 700 CCA for $6 more. Let's see, Autozone is 30 miles closer, wants to sell me a better battery. Between the two, I'd choose Autozone. We're considering a 2000-mile roundtrip in this van in the next two weeks, so a new battery might be a good idea...

    BTW, I finished the car stereo install on this vehicle successfully earlier today.
    What broke, uh, needs upgrading now?

  13. #13
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    Quote Originally Posted by Jimmie Neutron View Post
    When you let off the gas, the alternator is no longer spinning up fast enough to produce a higher voltage... resulting in a voltage dip. If the battery is under-rated for the car or nearing the end of its life, you will see a difference in brightness of the headlights.

    How much of a difference is there?

    To some degree, this 100% normal... and chasing down a problem that really isn't there can be quite costly.


    On another note, I have had batteries tested by places like Autozone die within days of them claiming it is OK.
    I've only driven the car at night a couple times since getting it, but it was really, really noticeable.

    When they did test it, they only looked at the alternator voltage while it was idling, it stabilized at about 14.4V, I think. My parents said when they had the vehicle before giving it to us, they also had it tested at the Hyundai dealer, who told them everything seemed to be working as it should be and "that's just how this vehicle behaves..."

    We may try the battery replacement, may even consider the HID bulbs later if they're not too much money, but I think it has to be related to the alternator, like you said, Jimmie, since it dims with only letting off the gas, where there is no new sudden electrical load, such as brake lights. I'll have to check tonight and see if it dims more when I brake than just when I let off the gas (i.e. alternator slower + electrical load of brake lights). As you say, this may be a normal electrical phenomenon, but worsened by a weak or under-rated battery. I'll post more updates if we do replace the battery.

    Thanks for all the input, fellas!
    What broke, uh, needs upgrading now?

  14. #14
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    Checked battery under the good and it is currently a BatteriesPlus 540CCA battery, so we've decided to replace it with at least a 700CCA. Hopefully that will reduce this phenomenon...
    What broke, uh, needs upgrading now?

  15. #15
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    At least your headlights work. Mine only have really dim and if you hold the switch they go to simply dim.

    Watch this!!!!...........oops.
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  16. #16
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    Make sure all of your connections are clean and tight. Check at the battery, alternator, and fuse box. Check grounds, especially to the chassis. Check the grounds close to the headlights also. I have seen vehicles after front end repairs with loose grounds behind the grill, or bumper. Good luck. There is nothing like electrical gremlins
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  17. #17
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    Quote Originally Posted by westoakmech View Post
    Make sure all of your connections are clean and tight. Check at the battery, alternator, and fuse box. Check grounds, especially to the chassis. Check the grounds close to the headlights also. I have seen vehicles after front end repairs with loose grounds behind the grill, or bumper. Good luck. There is nothing like electrical gremlins
    I'll try and check the grounds you mentioned. That'll take a little while to do.
    What broke, uh, needs upgrading now?

  18. #18
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    Electrician at work suggested cutting the terminal off the negative cable in case corrosion has worked its way up into the sealed power cable. Haven't tried it yet, just sharing additional ideas.
    What broke, uh, needs upgrading now?

  19. #19
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    A higher CCA battery will have no effect on your headlights dimming. CCA= cold cranking amps. Which means you will have more cranking power.. that's really about it. No battery is more powerful than another other than in cranking amperage. They all need to make 12v in a standard automobile, and that's it.

    My guess is you have a weak ground. Check the terminals at your battery first, and move from there.

  20. #20
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    yes double check your grounds, and maybe even do the big 3 wire upgrade.

    PLEASE don't instal hids unless you do a propper projector retrofit... last thing you need is to drive around blinding people due to glare from a bulb installed in a housing designed for halogen bulbs.
    also, if you have a voltage drop, it may drop low enough to shut down the ballast feeding the hid, causing it to go out and then need to warm back up.

    also, check your serpentine belt, it may be worn and slipping or stretched a bit, although it should be more noticable under acceleration... but you never know.

  21. #21
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    It rained today and my garage is full of junk but hopefully it will be clear tomorrow.

    Will start with wire at terminals and check from there.

    3 wire upgrade?? Total battery cable replacement?
    What broke, uh, needs upgrading now?

  22. #22
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    FIXED!!! $0. Very easy.
    What broke, uh, needs upgrading now?

  23. #23
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    Removed negative battery terminal to chassis ground wire. Was trying see if it had any corrosion. Didn't see any, but saw that chassis where wire attached had white paint on it.

    Put wire brush on dremel, removed paint and wire brushed chassis terminal. Reconnected, waited til dark to make test drive.

    Result = no more dimming!

    Hooray!
    What broke, uh, needs upgrading now?

  24. #24
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    big 3 wire upgrade is replacing stock wire with 4ga or larger in the most critical areas:
    1. battery ground to chassis
    2. motor ground to chassis
    3. alternator positive to battery

  25. #25
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    Ok, thanks for explanation of 3 wire upgrade.

    Update: wife did her test drive. She says it's much improved but still dims some, so I will be replacing the battery ground to chassis cable. Already ordered stock replacement cable. Should come Tuesday. Not sure what gauge the wire is, but it's #1 on that list.

    I'll keep the Big 3 wire upgrade in mind, but hopefully the other two won't be necessary.
    What broke, uh, needs upgrading now?

  26. #26
    RC Turnbuckle Jr. harry697's Avatar
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    Quote Originally Posted by OlorinTharkun View Post
    Ok, thanks for explanation of 3 wire upgrade.

    Update: wife did her test drive. She says it's much improved but still dims some, so I will be replacing the battery ground to chassis cable. Already ordered stock replacement cable. Should come Tuesday. Not sure what gauge the wire is, but it's #1 on that list.

    I'll keep the Big 3 wire upgrade in mind, but hopefully the other two won't be necessary.

    Quote Originally Posted by OlorinTharkun View Post
    Removed negative battery terminal to chassis ground wire. Was trying see if it had any corrosion. Didn't see any, but saw that chassis where wire attached had white paint on it.

    Put wire brush on dremel, removed paint and wire brushed chassis terminal. Reconnected, waited til dark to make test drive.

    Result = no more dimming!

    Hooray!

    Has this vehicle ever been in a front end collision?

  27. #27
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    Quote Originally Posted by harry697 View Post
    Has this vehicle ever been in a front end collision?
    Not to our knowledge. My parents bought with 3500 miles in 2006. None while they owned it.
    What broke, uh, needs upgrading now?

  28. #28
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    Quote Originally Posted by ling427ttvette View Post
    A higher CCA battery will have no effect on your headlights dimming. CCA= cold cranking amps. Which means you will have more cranking power.. that's really about it. No battery is more powerful than another other than in cranking amperage. They all need to make 12v in a standard automobile, and that's it.

    My guess is you have a weak ground. Check the terminals at your battery first, and move from there.
    Glad to say this advice was incorrect. Replacing the battery made things noticeably better. Whether that's because the old battery was on its way out or that the higher amp rating made a difference, I don't know.

    Went ahead and installed the 700CCA larger battery (actually fits stock battery clamp, unlike stupid BatteriesPlus one). My wife says the headlights are noticeably brighter and dimming is now almost unnoticeable. Two things improved it: 1) removing paint interfering with good ground; 2) installing the stronger battery

    I still intend to replace the negative ground cable, but the Hyundai dealer is an hour away and wants $15 to ship me the cable, so I'll do that when I'm in that area.
    What broke, uh, needs upgrading now?

  29. #29
    RC Turnbuckle Jr. DiggerPede's Avatar
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    I would also check the serpentine belt like morehouse said. I like Goodyear Gatorback belts.

    also, check your serpentine belt, it may be worn and slipping or stretched a bit, although it should be more noticable under acceleration... but you never know.
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  30. #30
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    Quote Originally Posted by DiggerPede View Post
    I would also check the serpentine belt like morehouse said. I like Goodyear Gatorback belts.
    I'll have to check that too. Have not done so yet.
    What broke, uh, needs upgrading now?

  31. #31
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    Olorin, I got to this thread late, but I have a Hyundai as well and I had the same problem for over a year. The lights would dim when I slowed down and if the stereo was loud, it would actually blink the light. I worked for Hyundai and they said nothing was wrong with the system. This past winter after a long cold spell on the east coast the battery finally quit. Put in the recommended battery from auto zone as well and the headlights work perfectly now. Glad you figured it out before I chimed in, but its simple with cars. Weak battery will show up faults under heavy loads. The car may start fine, but that doesn't mean the battery is good. My battery was 8 years old and I kind of knew it was the problem.
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  32. #32
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    Cen, thanks for sharing! I think the battery was the #1 culprit but the paint on the chassis ground didn't help either.
    What broke, uh, needs upgrading now?

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