Alternator Replacement

This is the first in a series on routine maintenance. These posts will cover basic maintenance that applies to all trucks.

Trucks of all varieties need regular maintenance

The Ford Super Duty is no exception. Our customer with a 2003 6.0 super duty came in with the request to change his alternator. When we double-checked the volts on the alternator with our multimeter, the results were obvious, this truck was in need of an alternator.

The alternator should be putting out more volts than the battery has, in order to keep the battery charged. If the alternator is generating the same or less than the battery charge, then it is time to change the alternator. Other signs that it is time to change the alternator are:

• A red warning light on dash
  
• Intermittent red warning light on dash
• Dim lights- most often you will notice the headlights are dim, sometimes the interior lights will also dim
• Slow cranking
• Dead batteries
  

Before replacing the alternator the battery charge must be 12.5 volts. The alternator acts as a voltage maintainer, it is not a battery charger. If your battery is dead to begin with you will over work the brand new alternator, or it may not work at all!

The voltage regulator (a component of the alternator) needs to be controlling the voltage output between 13.5 and 14.2 volts with the engine on and no load. This range will ensure your battery is charged correctly.

Another cause to replace your alternator would be if the voltage regulator is overcharging your batteries, causing them to spew acid. In this case the readings on the alternator would register over 14.5 volts.

Nearly all vehicles run on a 12 Volt system and the above standards apply, including all size trucks, semis, cars, motorcycles and boats.

Updated 2/21/14