I'm getting B1484 brake pedal input open circuit code. When I turn on lights or hit brakes volt meter drops and battery light comes on. I took brake light switch apart and cleaned it all brake and tail lights work. ABS light is not on. Any ideas?

 

What are you working on?

 

Sorry thought I stated it's an 04 F150

 

In 04, there were the old body style (heritage) and then the new body style.

I would start by looking at the brake switch and master cylinder components.

 

It's the new body style. I took the brake switch
apart and cleaned it, the contacts open and close as they should.

 

I would start checking the wiring, 3rd brake light, and the fuses.

Here's some help:

http://www.devoll.com/Public/f150-wi...Pedal-SW-1.pdf
http://www.devoll.com/Public/f150-wi...Pedal-SW-2.pdf
http://www.devoll.com/Public/f150-wi...Pedal-SW-3.pdf
http://www.devoll.com/Public/ELECTRI...OCATOR~CJB.pdf

 

All 3 brake lights work so it shouldn't be a wire, but I'll check the fuses/ relays

 

Then the only other thing might be a weak alternator or your battery is getting old. Though brake lights don't draw nearly as much as starting.

If the wiring and fuses check out fine, then the next step is the alternator. I would get it tested. <-- Only because of the battery light and voltage drop only when you hit the brakes.

How old is your battery too?

 

I replaced the battery and alternator less than a year ago. So with that and the b1484 code I was sure it wasn't either of those, but everything kept pointing back to the alt. Had it tested and it failed. Put the new one on and the problem seems to be fixed, just not sure why that would give me the abs code. Thanks for the suggestions.