Rick's Free Auto Repair Advice

Ford Focus Alternator Problems

How to fix Ford Focus alternator problems

If you’ve replaced the alternator several times and still have Ford Focus Alternator Problems and have replaced the alternator only to find that it still doesn’t work, follow these steps. If you’ve already replaced the Ford Focus alternator and it still won’t charge, this post is for you.

You’ll need a digital multimeter to do this test. They’re not expensive. There is NO other way to test the alternator (unless you own a scope). Do NOT disconnect the battery with the engine running. That is NOT a safe way to test the alternator. In fact, it’s a great way to fry all the computers in your vehicle. See this post:

Check charging voltage

First, check the voltage at the battery terminals with the engine running and the headlights, blower motor, and wipers on. Rev the engine to 2,000 RPM and hold it there for 3 minutes. The voltage should read at least 13 volts. If it’s lower than that, perform a voltage drop test between the battery and alternator case.

Perform a voltage drop test

Perform these tests with the engine running.

1) Set the meter on DC volts

2) Connect one meter lead to the battery positive post and the other lead to the B+ terminal on the alternator. Note the voltage.

3) Connect one meter lead to the battery negative post and the other lead to the alternator case. Note the voltage.

The results should be less than 0.50 volts. Shops are reporting Ford Focus Alternator Problems due to excessive resistance in the ground circuit. The Focus alternator grounds to the engine just like every other alternator—through the bracket. Apparently, corrosion buildup degrades the contact over time. If you have a high voltage drop, try connect a jumper wire between the battery negative and the alternator case. Then check battery voltage. If battery voltage goes above 13-volts with the jumper, you’ve found the problem.

One solution is to remove the alternator and clean all the mechanical connections to remove the corrosion. The other option is to install a permanent jumper wire between the battery negative and the alternator case.

©. 2015 Rick Muscoplat

Posted on by Rick Muscoplat


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