Alternator?

[n0c7]

Battery voltage(decent Optima Redtop battery, less than 2 years old) reads 12.4V while vehicle is off and has been sitting over night. Turn the engine on, voltage drops to 11.2V. This tells me the alternator is bad from previous experiences. Any other parts known in this generation of explorers(regulators maybe) that I should consider before replacing the alternator?

 

[BrooklynBay]

The regulator is built into the alternator. You could test the rotor to see if you get continuity. If not, then it could have bad brushes or a blown out rotor.

 

[n0c7]

Hmm, something isn't right. I was probing the connectors to the alternator to check for voltage. I was still getting 11V with the ignition on now(maybe the battery was run down a bit if the alternator is on its way out). When I restarted the truck, now the battery and alternator are showing 14.7 - 14.9V. I can't see anything wrong with the connector, all I did was wiggle it. Could it be a bad harness/connector is is the alternator on its way out and acting temperamental?

 

[BrooklynBay]

Which wire did you wiggle? Did it show a charge light on the dashboard when it wasn't charging? Do you have a volt gauge? If so, then is this how you knew that it wasn't charging?

 

[n0c7]

Which wire did you wiggle? Did it show a charge light on the dashboard when it wasn't charging? Do you have a volt gauge? If so, then is this how you knew that it wasn't charging?

The harness with 3 wires, and the single large wire(with rubber cap). The battery light was on the dashboard. Volt gauge was low. Those were the first symptoms, then I busted out my trusty voltmeter which quickly verified the voltage issue.

 

[BrooklynBay]

Check each of those wires separately. There might be a bad connection in the plug in connector or in the alternator.

 

[n0c7]

Check each of those wires separately. There might be a bad connection in the plug in connector or in the alternator.

What's the best way to test it? Disconnect the harness from the alternator, turn ignition on, and probe the female ends individually looking for 12V?

 

[BrooklynBay]

You could start with a continuity check of each wire from one end to the other.

 

[n0c7]

All wires and voltages still checked out as far as I could tell. Every second day it would drop back down to 11V. I swapped out the alternator and gave the battery a full charge. We'll see how it goes now.