Voltage Regulator or New Alternator

I have a 1997 Saab 900S. Recently, my battery was completely drained and my car wouldn’t start. I took the battery back to Sears to be tested since it was under warrenty. Turns out, once the battery was fully recharged, the battery tested fine. Many mechanics I speak to are telling me it is the alternator that needs replacing as it is not charging the battery when I am driving the car. But, I recently read this on thesaabsite.com, where I buy my parts:

Alternator issues typically come from Voltage regulator brushes getting too short which causes the alternator to not charge correctly. If the battery voltage is low then the computers on the vehicle will not be supplied with enough voltage to operate the fuel system or the ignition system. Typically this range is below 11.5 volts but may vary depending on the car. When this happens it is usually the ignition system starves for voltage which causes fouled plugs because there is not enough spark to burn the fuel efficiently. You will also need to check the alternator amperage output to see if the alternator is failing internally.

This description sounds word for word what my problem is. The price between a new alternator and voltage regulator is significant, so wondering if before I get a new alternator, maybe it is best to have the voltage regulator checked. Any thoughts on this?


Have you figured out what it takes to change the regulator? On most newer cars, it’s integrated with the alternator and is a bit of a job to separate the two, and so usually you just go ahead and get a whole new alternator assmebly if the regulator is bad.

I’m not sure there even is a very good way to test an integrated regulator, short of swapping it out.

Voltage regulators don’t have brushes, alternators do.
If your Saab is like most cars, then the voltage regulator is built into the alternator anyway.

I was wondering if that was the case, if the brushes were inside the alternator. Sounds like the easiest option is to swap out the alternator. Thanks guys for the comments.


The brushes are separate from the voltage regulator but both inside the alternator. This used to be a fairly easy and common job to just pull the alternator apart and put new brushes, voltage regulator, and bearings in and you’d be good to go for another 100K. The leads on the voltage regulator used to be just bolted in but now are usually soldered or crimped on, making it a chore. Plus some of the alternators are tough to get apart now without the proper tools. Short answer is just replace it.