Head Lights dimming when I press the brake pedal.

Sounds like a weak battery to me...

 

I noticed this too. My headlights dimmed slightly when applying the brakes.... Until I replaced a bad battery. Now it seems to be better. It doesn't really make sense because I thought the alternator provides all power when the truck is running. Does the battery sort of act as a capacitor for heavy current surges? I guess that would explain my situation.

 

I tested my battery and it was reading healthy, my next test will be an alternator ripple test in a week or so.

 

Your battery is about to go kaput.

 

Either battery, alternator, or a bad flasher. Bad flashers, even if they are still working, will cause this.

 

The battery does not act like a capacitor. It may be weak and taking load from the alternator and not enough for the other items eating AMPs. The problem sounds like there is way too much draw on the alternator to start. All of this stuff takes juice to run. If you have a lot of LED bars, after market lights, etc. Some of this Chinese made stuff will be poorly designed and cause such issues. I was just wondering if there is a larger after market alternator to go with myself when coming across this.

 

Brand new 2019 trd off road. Brakes are electric. When I push brake when car is in park there is slight buzz in brakes pedal and if doors are open lights dim for a second.

 

Mine has started doing the same thing taking it in tomorrow to have it looked at.

 

Mine is a 2017 IR and just started doing it the last couple months. Local shop couldn’t figure out why.

*OR

 

I'm starting to think it *could* be battery related....ive noticed recently when I have my interior lights on while driving for my daughter in the back Seat. whenever I shift to neutral and rpm drops I'll immediately notice the dome lights briefly dim. My headlights don't seem affected just the dome. I never noticed if it's linked to pressing the brake or not. I'll have to keep an eye on it. Battery seems fine, holds a cold/winter charge around 12.8-13.0. But then again it is coming up on 4 years old so I wouldn't be too shocked to see its on its way out. I'll most likely change it out by next winter because I'd rather not get stranded somewhere.

 

sounds like a bad solenoid or relay/switch

 

My 2016 TRD OR has been doing this exact thing for 40,000 or so miles, have about 80,000, now. Haven’t even thought about looking into it, and probably never will.