Brake pedal hard to push only when starting

[MarcusTriton]

2012 LR4 HSE Brake pedal is hard to push with very little pedal travel. This interferes with starting of the engine as the push button will not engage.
After I get it started(by pushing pedal very hard) and go somewhere shopping, turn off the engine and come back after 10 minutes or more, it works as it should for the rest of the day with proper pedal travel and button pushing.
Any ideas of what is causing this would be greatly appreciated. TY.

 

[ftillier]

Sounds like your vacuum assist lost vacuum. If you stop the car when it works as it should, and then pump the brakes a few times, the pedal should get progressively stiffer and have less travel. Does it feel the same as the original condition you're describing? The start button should work off of the brake switch, which on my LR4 is extremely sensitive. After pumping the brakes to use up the residual vacuum, if you turn the ignition on without pressing the brake you'll get a yellow warning triangle light at the top left of the central display in the instrument cluster. When you press on the brake, that light should turn off, even if the pedal is stiff. When you release the brake, the light should turn back on. See if yours does that, it should help rule out the brake interlock/brake switch. If the yellow warning triangle toggles with the brake pedal then it might be the push button switch itself, but try the above and report back.

 

[MarcusTriton]

Sounds like your vacuum assist lost vacuum. If you stop the car when it works as it should, and then pump the brakes a few times, the pedal should get progressively stiffer and have less travel. Does it feel the same as the original condition you're describing? The start button should work off of the brake switch, which on my LR4 is extremely sensitive. After pumping the brakes to use up the residual vacuum, if you turn the ignition on without pressing the brake you'll get a yellow warning triangle light at the top left of the central display in the instrument cluster. When you press on the brake, that light should turn off, even if the pedal is stiff. When you release the brake, the light should turn back on. See if yours does that, it should help rule out the brake interlock/brake switch. If the yellow warning triangle toggles with the brake pedal then it might be the push button switch itself, but try the above and report back.

Thanks for the reply ftiller.
So I turned the ignition on without pressing the brake and saw the yellow warning triangle light at the top left of the central display in the instrument cluster. I pressed on the brake and light turned off. When I released the brake pedal, the light came back on. I haven't yet stopped the car when it works as it should, and pump the brakes a few times, but I will soon and I'll let you know. TY.

 

[djkaosone]

I had this exact issue before, it'll work normally for a couple of days, and then out of nowhere it won't start again.

Long story short, to fix it I had to recalibrate my transfer case with the gap iid tool. To do that part of the process is to start the truck. Make sure you're not having this issue when you're recalibrating. I may have posted this on this forum.

 

[MarcusTriton]

Sounds like your vacuum assist lost vacuum. If you stop the car when it works as it should, and then pump the brakes a few times, the pedal should get progressively stiffer and have less travel. Does it feel the same as the original condition you're describing? The start button should work off of the brake switch, which on my LR4 is extremely sensitive. After pumping the brakes to use up the residual vacuum, if you turn the ignition on without pressing the brake you'll get a yellow warning triangle light at the top left of the central display in the instrument cluster. When you press on the brake, that light should turn off, even if the pedal is stiff. When you release the brake, the light should turn back on. See if yours does that, it should help rule out the brake interlock/brake switch. If the yellow warning triangle toggles with the brake pedal then it might be the push button switch itself, but try the above and report back.

After traveling and the engine is warmed up I'd stop the car and pump the brakes a few times, the pedal gets progressively stiffer and have less travel and works fine.
After traveling and the engine is warmed up to the proper temperature and leave it off for an hour or so, the starting system works as it should also. The stiff braking only occurs on a new day start up when the engine is cold. It's that next morning or day, that I have a very stiff brake pedal and virtually no brake pedal travel which then doesn't allow the start button to engage the start up process. SMH, Still can't figure it out.

 

[f1racer328]

You definitely have a vacuum leak.

 

[ftillier]

On the next morning, the system doesn't detect that you pressed the pedal (yellow triangle light doesn't turn off when you press)? I agree you have a vacuum leak, but you might have a bad brake switch too.

 

[MarcusTriton]

On the next morning, the system doesn't detect that you pressed the pedal (yellow triangle light doesn't turn off when you press)? I agree you have a vacuum leak, but you might have a bad brake switch too.

Then I guess I'll just have to check both. Mo $$$$$
Thanks, appreciate it.

 

[MarcusTriton]

You definitely have a vacuum leak.

2 votes for vacuum leak, 1 vote for brake switch and 1 vote for re-calibration of the transfer case.
Any other takers?
Thanks for the input.