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Alternator takes time

When I start my truck after it has been sitting for a while… I.E. Everything is cold.

It takes about 2-3 seconds for the alternator to start putting out voltage (the lights are dim, and the voltmeter on the dash registers about 11 volts).

My question is: Am I running on borrowed time and should I change out the alternator, or is there another underlying problem I should be looking for? OR… is this normal; I’ve never seen this before.


2002 s10 p/u 4cyl stick shift

If you need more info, feel free to ask. I’ll answer to the best of my ability.

This is not normal.

Don’t just replace the alternator, check the charging system. It could be as simple as a loose connection or corroded wire end that is causing your problem. Also, this factory set-up requires a voltage signal from the ignition switch to turn on the regulator and field windings. The problem could be in a corroded fuse or switch. I believe the alternator light is also tied to this voltage signal. When the key is turned to ignition, but not started, does the battery light go on? Does it stay on until the voltage picks up to 13.5V-14.5V?

How many miles on this vehicle? 100-150k miles?

My guess is the alternator brushes are worn down and not making firm contact with the slip rings.

It is possible to just replace the brushes for not much $.

Many current alternators are wired through the ECM and will not charge until the computer has completed its start up check list and closes the circuit. Once running the computer will disable the alternator when accelerating quickly. You might check the wiring on your truck for such a function. And if when the engine first starts the indicated voltage is 11 the battery may be getting weak. Play it safe and get the entire system checked.

There is no battery light. Just a voltmeter, and if one of the gauges isn’t within normal range the “Check Gauges” light is illuminated. I’ve only ever seen this light come on when I first turn the ignition on and it goes through the test sequence.

103,000 mi

Thanks I will look through the factory service manual and see about the proper function of charging system.

Have you checked to make sure the belt isn’t slipping on the alternator pulley?

Upon a look at my dash… I do have a battery light and it is working normally. I will check it next time I have a cold start and post back any anomalies… Also what I find from looking in the service manual.

Working normally means it is on with the ignition switch on, but engine not running. When the engine is started, the light should go out immediately. Does it work like that?

so, I finally got my got my charging system checked as suggested. The mechanic said everything looked good. He had me hold it at 2000RPM and load tested it with a snap-on tester. I didn’t write down the numbers, but his tester started smoking so that leads me to believe he loaded the bejesus out of it. He also looked at my belt and said I’m due for another one, but that it wasn’t slipping. He also tested the battery separately and said it was strong.

Also, new symptom: when I turn on the headlights or blower the volts will drop then immediately rebound to normal.

My plan: Change the belt before I get stranded, lol, and then continue to drive while being mindful of my voltmeter on the dash. Any other suggestions?

Sorry for taking so long to get back to you guys. Thanks for the help.


I have a '98 Pontiac Bonneville that has been doing the same thing since I bought it 4 years, 60,000 miles ago. Surprised me at first, watched it closely. But now I don’t worry about it. Seems to be normal for my car. And, yes, the volts drop momentarily when you add an electrical load. All my cars do that. Again, I consider that normal.

I don’t believe this is normal operation of the charging/starting system. It is the job of the battery to carry the load/s, and it’s the job of the alternator to keep the battery charged. If you have a noticeable drop in voltage form turning accessories on then there’s a problem. Could be something as simple as corrosion, or your battery could truely be bad. or maybe a bad cable. But rest assured this is NOT normal. get a second opinion. The Zone will test for free I believe.