1999 Nissan Quest 99 Nissan Quest

Hi Welcome back to the forum. The place to start is by opening the bleeder screw when the caliper is locked up. If it doesn't release, check the mounts for rust, pitting, bent pins, etc. If it does release, you know it's a trapped fluid issue. Start at the master cylinder and crack open a line to see if the caliper releases. If it does, suspect the fluid is contaminated with petroleum product. If it doesn't release, work your way down the line toward the caliper cracking fittings open until the caliper releases. That will pinpoint the area of fluid restriction.

Also look for rubber hoses that have a metal support bracket in the middle of them. Rust can build up inside where that bracket is crimped around the hose and constrict fluid flow. When that happens, you will also have an unusually high and hard pedal.

Caradiodoc

I don't understand what you wrote. I know you said you replaced the hose and caliper. Are you saying the caliper released when you opened a line at the master cylinder? If so, look for signs of fluid contaminated with petroleum product. The rubber bladder seal under the reservoir cap will be blown up and mushy. The only proper repair for that is to replace everything in the hydraulic system that has rubber parts and to flush and dry the steel lines. That's a real expensive repair, especially if you have anti-lock brakes.

If the fluid appears to be ok, check for a brake light switch that is out of adjustment and holding the brake pedal down a little.

Caradiodoc