Brake light when going uphill
 

Hey Everyone,

So I have a strange issue that I can't seem to figure out. So, I'll start by saying that the brake fluid reservoir is full and that all brake pads are in good shape (I checked them over the weekend).

When I am driving uphill for about 1/2 - 3/4 of a mile my check brake light comes on and dings 3 times. This doesn't occur any other time and doesn't occur on short hills. There is no loss of braking. I can stop normally or stomp on them and the truck stops as it normally would. Once I stop, and restart the truck the light is gone until the next hill.

I did have one instance where I was driving uphill, the light came on and someone swerved in front of me. I hit the brake pedal (which was VERY firm) and the truck barely slowed down. That was the one and only instance of an issue.

I have tried grabbing codes when the light is one but there isn't anything showing up.

Any thoughts?

Thanks in advance

------ UPDATE -------
So I discovered about a week ago that when this beeping occurs that my brake pedal becomes very hard and almost won't depress. While still looking into this my truck began to produce another metallic noise almost like a loose exhaust shield. After crawling under the truck and looking for loose exhaust shields I discovered that my IWE wasn't fully disengaging and that I had a broken vacuum line on the passenger side of the truck. I replaced the line and since then I haven't been able to reproduce the brake issue once. Is there any possible way these could be related? It was the downstream line from the solenoid on the passenger side. Everything up to here still had vacuum.

What are you working on?

2011 Ford F-150 Supercrew FX4

Check your brake fluid!

Sorry, 2011 f150 supercew with the 5.0

Brake fluid is full and at all calipers. I bled them to make sure there wasn't air in the lines

I'm wondering if there was hydro static shock damage that damaged the sensor when you pulsed the brake to avoid a collision with that car. Just as wild-a-guess.

ManualF150 - would this trip the ABS warning light also if it occurred? For as cheap as these sensors are 'm willing to replace them.

The truck drives fine still but I pull a 7,200lb trailer and we're heading into camping season so I'm a little nervous about this issue.

No, if it's just the fluid sensor, then no.

I'm tempted to say replace just that sensor, but I'm not really sure without looking at it.

See what happens if you disconnect it and turn the truck on. See if you get anything different.

So I was able to crawl under the truck and give it another go through this weekend and found something suspicious. There is a sensor on my rear differential housing on the top that has wires that trace in with my brake lines. I'm taking this to be the rear ABS sensor. There is about a softball size area around that sensor that is covered in oil. It's not soaked or visibly running but appears to be a very slight leak over time.

Is this normal for the sensor? I've already ordered this part to attempt to replace it for $35. If it is this sensor any ideas why it would only trip when going up a long grade?

thanks everyone!

Sorry this thread was abandoned but here is what my fix was.

I started to experience some metal chatter from my wheel well and when I started to look into this issue I found that the vacuum line going to my IWE was broken. Fixing this vacuum line also fixed my brake issues as the vacuum used by the brake booster was being lost to the IWE. They share a check valve and vacuum system.

Weird how it came about but wanted to make sure everyone knew.

Thanks for all of the help