So I've noticed my dashboard lights finally working but sometimes its bright but it keeps dimming down. I don't drive the car at night as i found that sometimes when I come to a stop my car dies out. Front headlights are also bright but most of the time dimming down and back to bright then back down low. Any ideas where to look? I thought it could be the battery
66 Chrysler 300 - Lights Dimming
- Thread starter Umeracle
- Start date
If this vehicle has a mechanical type voltage regulator, it will kick in and out to supply charge as needed. You will most likely notice this at idle and it is normal. You should check the battery voltage with a multi meter. If you get a reading at idle with the engine running of about 13.2 volts, the charging system is working properly, you may notice a spike in voltage as regulator kicks in and out, this is also normal. Dim instrument lights and dim headlights can be caused by low voltage, but it can also be caused by a bad ground strap from the battery to the body. Check you battery cables for corrosion and check the body ground strap from the engine block to the firewall. Some cars also have another ground strap from the negative battery cable to the front fender.
Dave
1970FuryConv
Old Man with a Hat
You can start the car and check the voltage at the battery. If you then turn on the headlights and the voltage at the battery drops half a volt, you may need a rebuilt alternator. Voltage regulators are easy to replace. Could also see if a new one makes a difference.
I use the Putco plug and play headlight harness with relays on all my old Mopars.
No cutting or hacking of factory wiring.
Easy to install and eliminates the headlight dimming andd also take the high amp load away from the headlight switch and foot dimmer switch.
The relays are generic and easy to find if need replacing.
Amazon product ASIN B001P29X4G
No cutting or hacking of factory wiring.
Easy to install and eliminates the headlight dimming andd also take the high amp load away from the headlight switch and foot dimmer switch.
The relays are generic and easy to find if need replacing.
Amazon product ASIN B001P29X4G
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Here is a video of my 68 Newport with the harness. First high beam then low beam. Also i am usung Hella housings with Piaa super brite white bulbs.
Harness and bulb upgrades on our 69 Fury..
Last post...Very important to get headlamps aligned properly..
stubs300
Senior Member
Nothing except being able to see at night.
polara10x500
Member
It's simply incredible to be able to incorporate and put newer better technology into these 40 50 60 plus year old vehicles and make them safer and more reliable for us to enjoy in this day and age. Yes, I like to be purest in some respects but some of the old auto tech. was behind and Laking. I like better lights, reliable brakes, better ignition, less electrical stress in my dashboard and switches, less fires burning up classic cars from antiquated tech. This hobby and passion that we have for these cars is special. The knowledge exchange on this forum is phenomenal and has helped me so much in my endeavor's. So YES it has all to do with dimming light's.
I think this might be the case as when my foot is on the acceleration the lights on my dashboard and headlights are strong but when I hit the breaks they slowly dim out. Only thing is when I am at a stop and if I use any other electric such as putting the electric rooftop the car dies but rooftop still working perfectly. So once the rooftop is back on then I start the car again fine.
I had an issue 2 years ago with Frankie.
I installed an electronic voltage regulator.
New battery, alternator was charging at 13 volts
But..
The amperage output of the alternator was 4 amps.
Car would be dead or die with everything on.
New alternator fixed that.
Sure it had voltage but at next to nothing in amps it took all day to keep battery up.
Any load put upon the system the alternator could not keep up and drain the battery.
I installed an electronic voltage regulator.
New battery, alternator was charging at 13 volts
But..
The amperage output of the alternator was 4 amps.
Car would be dead or die with everything on.
New alternator fixed that.
Sure it had voltage but at next to nothing in amps it took all day to keep battery up.
Any load put upon the system the alternator could not keep up and drain the battery.
For me it just seems like the battery and I had a feeling it was. Battery just died on me and had to get it jump started. Replaced the battery with a new one and now car starts up fine and I can turn everything on without car dying.
Probably had a bad cell or low on water.
Gerald Morris
Senior Member
One CAN revive old batteries often with distilled water and epsom salts. (MgSO4) The epsom salts supply extra sulfate ion in solution, and drive a lot of the plumbous or plumbic sulfate BACK into solution from the weak potential of magnesium. BUT, this voodoo works only ONCE on old batteries, and only if they're sulfated and dry, as often happens.
I just buy new batteries usually nowadaze, though when pinching pennies, I used the epsom salts successfully, getting another 6 mos, and a year on some old batteries a couple times.
I just buy new batteries usually nowadaze, though when pinching pennies, I used the epsom salts successfully, getting another 6 mos, and a year on some old batteries a couple times.
Gerald Morris
Senior Member
Batteries do die, especially in summer heat, or freezing cold, but do yourself the favor of checking your alternator output and the voltage regulator all the same. How OLD was it?
thethee
Senior Member
If you don't mind me asking, how does one check alternator output? Can this be done at home?
You will need voltage multi meter and I just used youtube to figure out how to test alternator
Gerald Morris
Senior Member
Absolutely! The easiest and first check would be to make sure no accessories are turned on at first, then check your voltage right at the alternator charging stud. Do this at slow, then fast idle. Mopar alternators were designed to kick in at fast idle, usually over ~800 rpm on the pre-1970 stuff. At curb idle, you'll see basically battery voltage. You had BETTER see ~14-15VDC at fast idle! If NOT, then you can:
1.) "Hotwire" the field direct from the battery, then check your voltage @800+ rpm. If its still at battery voltage, chuck that alternator.
2.) Turn the headlights, heater fan, sundry other loads ON, check the voltage at the stud, goose up the idle again to say, 1000 rpm, note the voltage, and even try turning off one load at a time, noting voltage at each disconnect. A GOOD charging system should keep the voltage over battery voltage even when heavily loaded, so long as the engine runs above the minimum idle for engaging the charge circuit from the regulator to the field.
3.) If one has an "Amprobe" type inductive ammeter, then one can check the CURRENT from the charging lead on the alternator. OR, if blessed with an old style diagnostic meter equipped with a shunt and working meter, one can read THAT. These still can be had for under $100.
As you can see, home, shade-tree mechanic methods for checking alternators abound. One needs only a basic understanding of high school electrical rules to make an accurate call.
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