Dim lights while idle. Alternator?

[Kdouglas89]

My multimeter just died.

While idle, dash, headlights, tailights etc are all really dim. While driving everything brightens up. If I turn off car, it won't turn back on, even after a 30 min drive. The car does not die while running though.

Belt tension seems fine
Brand new optima battery

Would the alternator be putting out enough juice just to keep the car running?

 

[Rikolas]

I agree to pull the alternator and bring it to your local parts store to get it tested. I ran into a similar problem about a year ago. Let us know the results!

 

[DJ Raydiate]

Do not disconnect the battery while the car is running. Any car that has a computer should not go through this. Just do a search here in the forums why you should not. Best bet, like stated, is to just take the car to your local parts store and have them check it.

Do not disconnect the battery while car is running.

Do not disconnect the battery while car is running.

Do not disconnect the battery while car is running.

 

[My1GLaser]

Make sure your pos and neg battery terminal connections are clean and tight. That causes more no start and charging issues than you would think! I had a hairline crack in the pos battery connector and it gave me all kinds of problems cause it would never stay tight. I couldn't see it cause it was under the protective cover I have on it.

 

[Insomniac13]

That's exactly what happened when my alternator went bad. +1 for autozone or advance free testing, but like raydiate said please don't pull the wire off the battery while it's running. If you've got subs try turning the bass up and seeing if the lights dim whenever they kick in that happened long before my car began not starting.

 

[Turboturd]

Sounds like the voltage regulator in the alternator has gone bad. For whatever reason, these cars have a bad habit of killing the voltage regulator when the battery goes bad. Could also be the brushes on the alternator if it is really old, they wear down so much they can't generate any juice. Make them run multiple tests if the alternator passes the first time at the auto store, I've seen them be hit or miss sometimes.

 

[Kdouglas89]

Make sure your pos and neg battery terminal connections are clean and tight. That causes more no start and charging issues than you would think! I had a hairline crack in the pos battery connector and it gave me all kinds of problems cause it would never stay tight. I couldn't see it cause it was under the protective cover I have on it.

I actually just replaced a broken terminal today. The other one is in good shape. I will prob just buy a new alternator tomorrow honestly.

 

[WhiteVoid]

Walmart can also do a alternator/battery/starter test only takes a few minutes.

 

[Rikolas]

You know it's best to test the part before you buy a replacement right? Even if it's more than likely the problem, test it because it is free.

 

[DJ Raydiate]

^+1 A multimeter is cheaper than an alternator.

 

[Kdouglas89]

You know it's best to test the part before you buy a replacement right? Even if it's more than likely the problem, test it because it is free.

I am going to disconnect it, and bring it to advanced and test it. I am more than likely having to buy one, so I might as well get my core charge back while im there.

 

[second_amendment]

a symptom my first gen gave when the alternator was going bad was, when i would press on the brakes my cluster lights will dimly brighten up. After asking around different places those symptoms where signs of a tired/ bad alternator.

 

[pirkeltooned]

This guy is spot on! Keep in mind there is a REASON that many many components end up grounding through your battery, the frame wouldn't be sufficient for some of the sensitive devices. You could start with some simple multimeter tests to see what your battery is being charged to (At idle voltage, 2k rpm voltage). The "On vehicle" tests are pretty good, back in the day when I worked at an Autozone I used there machines are there pretty simple and effective.

It may also be worth your time to clean your primary grounds, especially the ones under fuse/relay box covers! It's hard to charge a system that isn't properly grounded, and lets face it, our beloved DSM's aren't getting any younger.

Also worth mentioning: They make some pretty slick alternator swaps depending on your goals with your car.

Whats keeping the car running is the battery but barley. Seems your alt. barely has enough left in it to charge the battery..The car dies and doesn't start because it isn't being charge.

Autozone or Advance can check this for you with it being stiil in the car for free. Check them out and let us know.

Also, a quick way to test it would be to disconnect the battery while the car is running. Oldschool method but still works on the older vehicles, not new. If the car dies/stalls, bad alt.

 

[Kdouglas89]

I brought my alternator in, tested it, and they said it was completely bad. I bought a new one. Just installed, and as I was pulling out of driveway it died. I jumped it again. As I was driving, my WB just started blinking 7.8 constantly. My oil pressure gauged dropped to the bottom, and it seemed everytime I would slow down to idle, it would want to die unless I put it in neutral and give it gas.

I am out of time today, so I can't mess around with it more. I will be purchasing another multimeter very soon.

 

[DJ Raydiate]

Yeah the battery should have had a full charge on it prior to installing the new alt.

 

[Kdouglas89]

Yeah the battery should have had a full charge on it prior to installing the new alt.

Should I put the battery on a slow charge over night?

 

[DJ Raydiate]

I would try it as well as get a multimeter. I don't know how picky the DSM alts are but I know that sometimes installing a reman or new alt on a car that has a dead battery could cause the new alt to go bad as well.

Put the battery on a charge overnight and get a multimeter. As the car is running, test the voltage at the battery. If it's showing 13+ volts, the alt would more than likely still be good.

 

[DSM1G90]

Disconnect the battery and slow charge it overnight .. or buy a new battery since the old one is what killed the alternator.

Why we don't disconnect batteries with the motor running is that the battery IS actually running the system and the ALT is keeping the current from the battery, since it's running in parallel with the battery, at an even pace - like a ballast in a florescent light assembly.

You pull the connection from the battery and the alternator suddenly gets super loaded down and this sudden load takes out the regulator in the alternator making the alternator useless.

 

[Kdouglas89]

Disconnect the battery and slow charge it overnight .. or buy a new battery since the old one is what killed the alternator.

Why we don't disconnect batteries with the motor running is that the battery IS actually running the system and the ALT is keeping the current from the battery, since it's running in parallel with the battery, at an even pace - like a ballast in a florescent light assembly.

You pull the connection from the battery and the alternator suddenly gets super loaded down and this sudden load takes out the regulator in the alternator making the alternator useless.

I never said anything about pulling my connections with the car running. I would never do this. The battery is an optimum that is about 2 weeks old. I was already having charging issues before I replaced battery.

 

[DSM1G90]

I know for I knew you had the good judgement on such,

but just making comment on that one user who made the comment on doing this forbidden practice...so he would know not to do this practice and to let others who see this to not do this and to tell their DSM friends the same.