Brand new battery, brand new alternator, battery light still on after resetting it

The lug was cleaned and tightened, the voltage is fine. I was told it could be my E.C.M.

if the voltage is fine, then it does not need an ecm.

thats why i want the actual voltage

Roy

For the past four months the battery light would stay on when car is started. If i shut car off and restart the jight would go out.Is this a sign the Alternator is going bad ?

It could be the alternator or the battery failing.
I would have them both checked, most major parts stores will do this for you free of charge.
Let Me know,
Dan

alternator light intermittently comes off and on in my 1998 chrysler sebring, The alt. & battary are brand new.

Measure the two voltages on the small wires on the back of the alternator while the engine is running AND while the light is on. Holler back with those numbers.

After car runs for 5-10 mins, battery light comes on and stays on. Stop car and restart, light stays off for 5-10 mins and comes on again. Battery replaced last month. Had All-Parts Automotive do the system test. When the light was off, they said alternator was fine and battery fine but low charge. I drove 10 mins, light came on, I had them test with light on. Test said battery was bad. Stopped car, had them restest and it says battery is ok. Battery connections seem tight and look ok. Car is a 1997 Sebring convertible. Any idea what the problem is?

Wait until the problem occurs, then measure the voltage on the two small wires on the back of the alternator. They will be two wires that are plugged in, or two wires that go through a black plastic block, then appear on two tabs that are held on with two very small nuts. The voltages will only be there when the engine is running.

One terminal must have full battery voltage. The secret is the other wire. It should be less than the first one but not 0 volts. Use an inexpensive digital voltmeter to measure them, then holler back.

caradiodoc

Thanks for the reply and suggestion. I appreciate it.
There are 3 wires, but I assume we're not talking about the big red one. Of the other 2, 1 was green with an orange tracer- it read about 12.9v on my analog meter (same as across the battery terminals). The other wire was solid green and 0 volts.
If you're going to say the alternator is bad, can you tell me why the store test said the charging system was ok (13.80v 29.7A no load and 13.81V 62.6A Loaded)?

Yup. REAL common problem. The brushes are worn and making intermittent contact. The testing has to be done while the problem is occurring. During their test, they caught it while it was working.

If you can find the parts, you might be able to replace the brush assembly without removing the alternator from the engine, at least that could be done on the older stuff that I drive. I've done this many times on cars I put "bugs" in for my students to troubleshoot.

Here's a photo of what the assembly looks like. You don't have to remove the terminal block as I did in the photo, just the three screws.

caradiodoc

Here's what the back cover should look like on your car. Notice the "ND" in the middle for Nippendenso.

caradiodoc

Ok i got a new batt three weeks ago and my batt light started coming on again but then it would go off for a few days. Then is started to die on me and i jumped it off and i took it in they couldn't find any thing wrong with the batt and then it just wouldn't stay started after i jumped it off. The repair shop says it may be the fuel pump but i don't think that is the reason. But what else could it be?

Is the battery going dead? I really question the fuel pump is the problem. Did they test the alternator?

Brand new battery, new alternator, and brand new re-manufacture ECM. ECM was corrupt i cleaned all the grounds to the chassis and cleared faulty codes. Only codes available was for heater control circuit and EGR. Any help with ambient air temperature location? I'm scratching my head on this one. Any experience with this issue would be greatly appreciated and helpful. I did clean all the grounds. And 3 weeks into this one, thanks in advance for your help.

More then likely you have an issue on the generator field control wire. Either a connector issue or the wire itself has a short or high resistance. I highlighted here in the wiring diagram.

We need to check for a short and measure resistance from end to end. Basically this is the wire that the PCM uses to control the generator.

We can confirm the generator is causing the light to come on if you check the voltage across the battery when the engine is running. There should be around 14 volts. If not then the light is coming on properly telling you the voltage is low.

Let me know what you find. Thanks

https://www.2carpros.com/articles/how-to-check-wiring