i have an 05 ram 1500 when sitting at a stop light at night the volt gauge does down under half way mark and lights dim till i start moving again would that be the alternator?

 

Hmmmm in my opinion it sounds like a battery. First thing I would do is check all my battery connections. Ensure they are good and no corrosion. Probably even disconnect them, clean and reconnect. Also check the black ground where it attaches to the block, ensure a good non corroded connection. If that doesn't resolve, I would have the battery tested, then the alternator. How old is the battery? Just because it holds a good charge ( above 12v) does not mean it is able to function under a load. If you have a voltmeter handy, measure the battery voltage with engine off. Should be above 12v. Then crank and re measure. Should go above 13v or more than you had with it off at least a volt or more. This is your alternator output increasing the voltage with it running. Many places can test your battery and alt for free.

 

I respectfully disagree with Kenney, though he is dead on about weak batteries having been known to do funky things..

general rule is: if the lights fluctuate brightness with RPM's, the alternator is not producing suitable power... the battery is in between, meaning the charge is pulling directly off the battery which doesn't have enough charge coming into it.. while the engine is running, unless there is a bad connection at the battery, the weight is on the alternator via the battery, and the battery basically becomes a big ol' capacitor which scrubs the power spikes the alternator can create, and gives you clean 11.5~14.5vdc...

all that said, Kenney is dead right in his approach- seeing as how the battery must have a good connection for any of it to work, and must be capable of holding/transferring a charge.. it is the only place to start t/s'n.. if there IS a good connection, though, and the battery isn't 'breaking' the circuit by having a dead cell, then it's your charge going into the battery..

it's been my experience and observation that fluctuating brightness is indicative of alternator about to take a dump..

 

Take off your battery terninals, give a thorough cleaning with a wire brush, apply either a dielectric compound or battery terminal spray and see if that helps. Might also want to clean your ground to block as well as that tends to get corroded.

The above might cost you 1hr and $5 in material. It's a preventative maintenance that should be done every year or two anyways. I'd do that and then go from there before spending unnecessary money.

 

....... and raid the medicine cabinet for Vaseline.. good ol' petroleum jelly on all connections will prevent them from corroding, and is cheaper and better than the spray stuff you can buy at parts stores..

 

Spary stuff seems to speed up corssion, but yeah if the lights dim with the RPMs, first guess ALT. Check it now or it will leave you on the side of the road

 

Never had any spray stuff speed up corossion. Yes it can attract dirt, but you need to keep it clean. It's not a one time and forever leave alone application. Should be done seasonally.

 

No worries Drew. Glad someone else is helping. Found this thread, jump to the 3rd page to see what the fix was. Interesting. https://dodgeforum.com/forum/3rd-gen...ernator-3.html

 

I stand corrected... and, I've found this weekends project, too...

thank you, sir!!

 

Its not ever been any spary stuff but the gel that speed up my corossion.
And yes that was a good read when we were helping him through that, good simple easy cheap fix, and i went out and sanded my down that day back to shiny metal