Testing the alternator, to see if it's good or bad, on your Dodge Neon (or Stratus or Caravan or Chrysler Cirrus or PT Cruiser or Voyager or any 2.0L or 2.4L equipped Chrysler, Dodge, Plymouth, Eagle) can be easily done with just a simple multimeter. You don't need any expensive or exotic diagnostic equipment. In this article I'll show you just how easy it is.
Contents of this tutorial:
Before you start, I want to tell you that this is an on-car test of the alternator, although the photo I'm using in TEST 2 shows it off of the car (or mini-van). Also, since ALTERNATOR TEST 1 has to be done with the engine running, you need to be careful, alert and take all necessary safety precautions.
ALTERNATOR TEST 1: Checking Battery Voltage With Engine Running
The first order of business is to check the battery's voltage, with a multimeter, while the engine is running. This simple little test will tell you if the alternator is really NOT charging the battery or it is charging the battery.
Now, before you start, the battery in your Dodge Neon (or Stratus or Cirrus or Breeze or PT Cruiser or whatever 2.0L, 2.4L equipped car or mini-van) must be fully charged, since the engine must be able to stay running for at least 20 minutes to do this multimeter test.
OK, to get this show on the road, this is what you need to do:
Set the multimeter in Volts DC Mode and start the engine in your car (or mini-van).
Check the battery's voltage by probing the positive battery terminal with the red multimeter test lead.
If the battery in your specific vehicle is not in the engine compartment but located under the passenger side fender well, just probe the stud on the strut tower that is labeled with the (+) symbol.
With the black multimeter test lead, probe the battery negative (-) terminal.
If the battery in your specific vehicle is not in the engine compartment but located under the passenger side fender well, just Ground the test lead on a clean and unpainted metal surface on the engine.
Your multimeter will display one of the following two readings:
1.) A steady 13.5 to 14.5 Volts DC.
2.) Or 12.5 Volts that will decrease the longer the engine stays running.
Now, the next step will put an electrical load on the alternator and will further confirm that it's either charging or not.
You need to turn every accessory possible inside the vehicle. Turn on the A/C or Heater on high, turn on the windshield wipers, turn on the headlights, turn on everything and anything that uses electricity inside and outside of the vehicle.
As you're turning On all this stuff, keep your eyes on your multimeter's voltage reading. Here's what is going to happen, you'll get one of following two results:
1.) The multimeter will register a nice and steady 13.5 to 14.5 Volts DC no matter what gets turned on.
2.) It will register 12.5 V DC and this voltage will decrease more and more as you turn on stuff inside your Honda vehicle.
Take a look at the following test interpretations to find out which one best fits your multimeter test results:
CASE 1: The battery's voltage, with the engine running and all accessories On, was between 13.5 and 14.5 Volts. This tells you that the alternator on your Neon (Stratus, Cirrus, Breeze, PT Cruiser, etc.) is good and charging the battery.
You don't need to do any other test, since this test result eliminates the alternator.
CASE 2: The battery's voltage, with the engine running and all accessories On, decreased down to 10 Volts DC. This tells you that the alternator is NOT charging the battery.
Now, with this result you could call the alternator fried and replace it. Most of the time (about 90%), this will solve your no charge condition. But unfortunately, one more thing could cause the alternator to not charge. So, what I suggest you do, is to verify one more simple and easy thing on the car. For this second test, go to: ALTERNATOR TEST 2.