Weird electrical glitch - charging system malfunction dash light flickers - bad alternator?

[Stynx]

05 xlt sport - Got stuck in a huge traffic jam getting out of the stadium lot the other night. We sat with the vehicle idling and the a/c on for about 20 minutes.

The I started getting an intermittent problem where I got what I THINK said "charging system malfunction" warning. It flashed on and off so quickly I had a hard time reading it. The red battery light went on and off at the same time as did an audible warning sound.

It seemed to stop when revved the engine to move or shut off the headlamps (had this thing for a few months and don't usually drive it at night). All the dash meters were normal - engine temp and voltage never budged. The radiator reservoir always stays at exactly the same level and never changes, the battery connections were tight. No codes and once we started moving the problem disappeared.

Could this be an alternator issue? The only things I could think of are a bad alternator or maybe a loose connection somewhere that only opens up when it gets hot.

 

[LMHmedchem]

You can test your alternator (mostly) if you have a DMM.

With the engine off, use a screwdriver to pry loose the red cap on the alternator. There are several designs, mine is just a flexible silicone cover. Don't do this with the engine running.

With the engine running, turn the DMM on to volts and connect the positive lead to the terminal under the red cap on and the negative lead to a ground on the engine. It should read between 15v and 16v.

If the reading is low, make sure that your S-belt is tight. If the tensioner in the S-belt system is starting to go, the belt will not be tight enough and and you will not get the required RPM on the alternator pulley. This can also happen if the belt is stretched.

If the alternator shows the correct output, you may have a different issue in the electronics. There are some other issues that could cause low output from the alternator, so low output is not definitive that the alternator is failing. The only way to get a definitive test of the alternator is to remove it and take it to a shop to be bench tested. Most chains (AutoZone, Advanced Auto Parts, etc) will have a bench tester. Call ahead because you may have to look a bit to find a shop that has a working test setup.

I would eliminate the alternate as an issue first because it's probably the easiest thing to test.

LMHmedchem

 

[Fix4Dirt]

i think it could be an alt, given that it took more revs to get sufficient power. you could take it to be tested at any big box parts store iirc

 

[Stynx]

i think it could be an alt, given that it took more revs to get sufficient power. you could take it to be tested at any big box parts store iirc

I did exactly that. autozone has a nice digital tool they use to test your battery, starter and alternator. The voltage regulator failed. They also had a compatible alternator in stock. Already fixed!