Jeep won't start, parking brake light on

I recently upgraded my front rotors to powerstop vented rotors from 4WD. Occasionally when I attempt to start the jeep, the only thing that happens when I turn the key all the way is that the parking brake light comes on. The brake pedal is extremely stiff and I have to stand on the pedal multiple times to try and start the jeep. The front pads were replaced when the rotors were upgraded, all boots looked good and everything works normally. The jeep will stop on a dime, no fade or anything else most of the time. This is the only time the parking brake light comes on (unless you actually engage the e-brake).

Thanks for any help or suggestions.

'97 Jeep Cherokee
K&N air charger
Powerstop rotors

Sounds like you have two problems. The brake warning light comes on when pressure in both halves of the master cylinder are not the same. This indicated an internal failure of the master cylinder.

You could have a bad rubber hose. As they deteriorate flaps from the walls form. They can act as check valves. It can either keep fluid from the caliper/wheel cylinder so it does not function OR hydrolock your caliper.

My first guess is a bad master cylinder. Install a new/rebuilt one and it should be fine. If you go that far also have the shop install new rubber hoses then the system is renewed.

On the hard to start problem could be a bad shift interlock system. This was installed to make sure your foot was on the brake before you could move the vehicle out of PARK. This still allows you to start the vehicle, just can't shift out of park... so put that as a distant second.

I do not know if on the newer XJs the master cylinder pressure is tied into the engine computer. If it is tied into the computer then a "safety" feature is being kicked in - prevent from starting.

You may want to take it to a shop and have them check it over. You have OBD-II so it monitors lots of stuff. I own a 88 XJ which does not store error codes so a 97 is out of my experience relm.

If it is the computer locking you out then there should be an error code in the computer - even if the light has not come on the dash board. I'd be prepared to a new master cylinder.

My brother has a Discovery, and he couldnt start his. Their is a switch in the break pedle that turns the break lights on, and lets the computer know that it is being pushed down, the switch might be bad.