Headlights dim when brake pedal pressed...anyone else?

Antman · 2014-09-16T12:07:08+00:00

Just recently this started happening: While running, when I press the brake pedal my headlights /interior O/H lights dim slightly and then return immediately to normal brightness. This is also accompanied by a slight drop in RPM at idle. The lights dim even if I hold the RPM's up 2,3,4k doesn't matter. Still a dimming and RPM drop for about 1/2 a sec.:confused: The voltage -while running- on the Scanguage shows 13.3V at idle (headlamps on), and then drops to 12.9V while depressing the brake pedal. Returns immediately to 13.3V. I verified these readings with the voltmeter too. When the truck is not running- headlights on/ brake depressed- no dimming at all. I checked all my battery connections and the alternator main wire- spotless and tight. Think I have a (going)bad alternator, bad diodes,regulator? I'm 99% sure I have the smaller alt. (100a) and I do demand a lot of it- dual batteries, thermo electric fridge, etc. I found this thread from a while ago which seems to be the exact same problem (ironically I responded to it, lol). http://www.toyota-4runner.org/5th-gen-t4rs/160114-lights-dim-when-applying-brakes.html#post1598296 Anybody else had this issue- resolution?