This is bizarre!

When I depress the brake (automatic tranny) the headlights dim momentarily and the radio goes off for a few seconds.

 

WTF??????

Check the battery. Mind did that when the battery was close to the end of its life.

Check the battery. Mind did that when the battery was close to the end of its life.

 

And check ATF, sometimes TC issues will cause this.

 

 

I'd have alternator AND battery checked for free at a chain place.

And maybe see what voltage you have when this is happening. I had something like this happen on a different car, and the radio going out was just a symptom. It had gotten down to about 10 volts (from idling for a long time with all accessories on and foot on brake). The radio started cutting out and I looked at the voltmeter and spotted the problem.

Good suggestions. I'll check it out. Thanks all.

+1 to alt and battery, another thing to look at is the fusible link, (big wire connector in the underhood fuse box) i'v had some issues there, it may be getting weak.

 

While the test is going on and the tester is on the car it will show the voltage on the system, i would have the parts guy look at it and see if there is a serious voltage drain while you hit the brakes, if it's any more than 1v you likely have a grounded wire on the way to the brake lights.

 

just my 2c good luck with it.

And check ATF, sometimes TC issues will cause this.

 

 

I'd have alternator AND battery checked for free at a chain place.

 

TC issues??? What is TC?

Torque Converter

Thanks. I hope it's not that. However, why would the TC affect the brakes and lights? What's the connection?

Sometimes usually if ATF is overfilled it's lke the TC doesn't disengage soon enough. Causing stalling like symptoms. Other than hearing the car's RPM's go way low often noticed by idiot lights, difficulting turning sharp, etc.

Another possible issue could be a loose power connection or chassis ground connection that is moving when the brakes are pressed. If you haven't cleaned the battery connections yet and especially the wire that runs from the battery to the power distribution under the hood I suggest you do that. If that doesn't fix the trouble then try tapping on various main connectors to see if can trace the trouble to one of them.

I love how tranny issue is linked together with this electrical issue.

 

Test your alt output. With EVERYTHING on and engine at 1800 rpm you should be getting over 13.5 volts.

 

Clean your batter terminals

 

If your still not sure remove the brake light bulbs and see if it still happens.

 

If not your charging system is border line or battery.