Hi I'm new to the forums so if I put this in wrong spot sorry in advance.
Working on friends f150. Brake light on dash is on. Not abs light, just to be clear.
Brand new pads front/back, calipers, master cylinder, fluid flushed and bled. E brakes work, tested e brake switch, metered good, makes contact press in with finger. Can't get light to go off. Every once in a while it will go off for a few seconds then back on. See about adjusting the rod in power booster but it seems spot on. Breaks feel little soft. Power booster seems to work. Car off, brake peddle is high and tight, start it it goes to the floor softly. Stops great but peddle seems very spongy. Any thoughts? Maybe something with power booster I'm not checking or another switch? Didn't change the resovoir tank and not sure about the plug there. Maybe that?

 

My experience with this was low brake fluid level. It may be the reservoir sensor.

 

Thank you for your reply. I forgot to say I found the issue. I looked everywhere then after I posted the question I found a huge thread on the instrument cluster. It's that. If I touch the top connection the light goes off and operates normal. Thread says I have to re solder some spots. Gonna give that a try. Thanks again.