This tutorial will help you test the alternator on the 2001-2002 Dodge Dakota and Dodge Durango equipped with the 4.7L V8 engine.
This alternator is computer (PCM) controlled and testing it can be done with a multimeter.
Contents of this tutorial at a glance:
You can find this tutorial in Spanish here: Cómo Probar El Alternador (2001-2002 4.7L Dodge Dakota) (at: autotecnico-online.com).
Symptoms Of A Defective Alternator
It's the alternator's job to charge the battery and provide the current that your Dodge Dakota's accessories need to run. By accessories I mean the radio, windshield wipers, a/c system, etc.
The alternator's current output is controlled by your Dodge Dakota's fuel injection computer (PCM -Powertrain Control Module). This is done by the Electronic Voltage Regulator (EVR) circuit inside the PCM.
Since the alternator is computer controlled, it's also monitored by it for problems. When a problem occurs with the charging system, the PCM will set an alternator trouble code.
When a charging system problem occurs, you'll see:
- Battery light is illuminated.
- Battery has to be charged for the engine to start.
- One of the following charging system trouble codes:
- P0622: Generator Field Not Switching Properly.
- P1492: Ambient Battery Temperature Sensor Voltage Too High.
- P1493: Ambient Battery Temperature Sensor Voltage Too Low.
- P1594: Charging System Voltage Too High.
- P1682: Charging System Voltage Too Low.
You can find out more about the Electronic Voltage Regulator in this section: The Basics Of The Electronic Voltage Regulator (EVR).
TEST 1: Testing Battery Voltage With The Engine Running
To get our alternator diagnostic underway, we're gonna' test the battery's voltage with the engine running.
If the alternator is charging, you should see a voltage reading between 13.5 to 14.5 Volts.
If your Dakota's (or Durango's) alternator is defective, you'll see a voltage reading of 12.5 Volts or less. This voltage will decrease the longer the engine is running.
Alright, let's get started:
Crank and start the engine and select Volts DC mode on your multimeter.
Probe the positive battery terminal with the red multimeter test lead.
Probe the negative battery terminal with the black multimeter probe.
Your multimeter is gonna' register one of two possible readings:
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 as you turn things on inside your Dodge Dakota (Dodge Durango).
Let's interpret your multimeter voltage test result:
CASE 1: Your multimeter registered 13 to 14.5 Volts DC. This is the correct test result. You conclude that the alternator is charging the battery and therefore it's not defective.
CASE 2: Your multimeter registered a voltage of 12.5 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: Making Sure The Alternator's Battery Circuit Has Continuity.