The alternator test, to find out if it's defective or not, on the 1994-1995 3.0L Ford Taurus is not difficult to do. You don't need any fancy or expensive test equipment since you can do the test with a simple multimeter.
And the cool thing is that you can do the test yourself to find out if the alternator is bad or not. All is explained in a step-by-step manner in this tutorial..
Contents of this tutorial:
You can find this tutorial in Spanish here: Cómo Probar El Alternador (1994-1995 3.0L Ford Taurus) (at: autotecnico-online.com).
Symptoms Of A Bad Alternator
Usually, when the alternator fails in your 1994-1995 3.0L Ford Taurus (or Mercury Sable), you are going to see the battery light shining nice and bright on the instrument cluster.
Unfortunately, this isn't the only symptom that you're going to see. Here's a brief/basic list of symptoms you'll see caused by a defective alternator:
- Charge light is on in the instrument cluster.
- The front headlights shine with a less than normal intensity (when you turn them on).
- The engine doesn't crank over. The only way you can get the engine to crank over is if you jump-start it with another vehicle.
- The engine only cranks and starts if you charge the battery first.
Let's get going with the first test.
TEST 1: Testing Battery Voltage With The Engine Running
The very first thing I'm going to ask you to do is to check the battery's voltage while the engine is idling.
This voltage test will confirm if the alternator is not charging the battery.
It's important that you perform this test with a multimeter. And what you're looking for is a voltage between 13 and 14.5 Volts DC. If you don't see these 13 to 14.5 Volts DC, while the engine is running, then you can conclude that the alternator is not charging the battery.
Alright, these are the test steps:
Crank and start your 3.0L Ford Taurus and select Volts DC mode on your multimeter.
Probe the positive battery terminal with the RED multimeter test lead.
With the black multimeter test lead, probe the negative battery terminal on the battery on your Ford Taurus.
Your multimeter is gonna' register one of two possible readings and they are:
1.) A steady 13.0 to 14.5 Volts DC.
2.) Or 12.5 Volts that will decrease the longer the engine stays running.
Put an electrical load on the alternator to further confirm that it's either charging or not charging.
You can do this by turning on every accessory possible (inside the vehicle). For example: 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.
Your multimeter will show you one of two things (as you turn on all of this stuff):
1.) The multimeter will register a nice and steady 13.0 to 14.5 Volts DC no matter what gets turned on or...
2.) It will register 12.5 V DC and this voltage will decrease more and more as you turn on stuff inside your 3.0L Ford Taurus.
Let's analyze your multimeter voltage test result:
CASE 1: Your multimeter registered 13 to 14.5 Volts DC. This is the correct test result. You can now conclude that the alternator is charging the battery and therefore it's not defective.
CASE 2: Your multimeter registered a voltage of 12 Volts and this voltage decreased the longer the engine stayed running. This test result tells you that the alternator is not charging the battery.
In about 90% of the cases replacing the alternator will solve the problem. But I suggest you continue to the next test to make sure: TEST 2: Testing The Continuity Of The Battery Circuit.