Hi,

I posted this in the 5th gen section (sort of), but didn't get an answer that satisfied. Here's the short version:

-Car has 243,000 miles
-When temps dip below 35, battery/brake lights on dash come on.
-After exactly 10 minutes, the batt/brake lights go off.
-Tested the battery out of the car - charges normally, passes the load test (4 of them, so far).

Folks said that the alternator is going out, but I've never, EVER had an alternator that worked, then didn't, then had a "timer effect"...they just died, the end, game over.

So, before I fork out the dough for a new alternator and go through the trouble of swapping it, can anyone say for SURE that it's the alternator?

What else could be going on? Why does it only do this when it's cold? Why does it come on after 10 minutes?

Any relays/fuses to check? Thought I found 'em all, but who knows.

Okay, thanks guys.

Jack

 

You have an alternator problem. That is what the battery and brake lights together tell you.

The voltage regulator has a transistor or integrated circuit that can't do its job when cold. In 10 minutes (or what ever) it warms up and works. Ask any electronics tech.

If you want to check the alternator out, before you start the car when it is cold enough for this problem, connect a voltmeter to the battery (or any spot that has 12 volts). Start the car and see what the voltage is. It should be around 14 volts. If the battery and brake lights are on, the voltage reading will be like 12 volts, meaning that the alternator is not charging.

 

Excellent. I've actually done a lot of electronics work, but didn't realize the regulator was inside the alternator.

Okay, alternator swap it is! I just wanted an explanation that addressed how odd the symptoms are!

Thanks!

Jack