Parking brake pedal still goes to the floor and parking brake barely holds the vehicle 2003 suburban

First, adjust the brakes manually. The cable that runs to the rear end has an adjustment near the frame on the drivers side.

Under the truck, on the drivers side, about in the middle of the truck is where the adjustment is. You will see the cable from the front going to the back. There is a long threaded bolt on the end on the cable. Lube it up good. and adjust it. If you can't get a good adjustment, replace the front cable, it is stretched to far.

Odds are that after 10 years of use ... you have broken the parking pawl in the transmission (or it has gotten mis-aligned)
Take it to a recommended transmission shop, and ask them to do as much diagnosing as they can without opening anything up. Pull codes, drive around, etc. Many shops will do this for free, then give you their recommendations on how to proceed.
If it is the pawl .... then after it is fixed .... every time you park the vehicle ... stop it by holding the brake and temporarily shift into "NEUTRAL", firmly press and hold the PARKING BRAKE pedal to the floor and let your other foot off the brake pedal. Slowly let your left foot off the parking brake pedal, making sure the pedal doesn't fly up. If it stays put, shift into "PARK" this rests the weight of the vehicle on the parking brake and NOT on the parking pawl in the transmission, prolonging its life.
Good luck on your troubleshooting

I had the same thing. just remove the cover from under the steering wheel and you can see the ratchet release lever. You can also remove the metal cover that is under the plastic cover for more visibility. now just reach in with a bit of stiff wire with a hook on the end and pull the lever back to you. that is all the cable does, and voila, the brake is released. now you just have to remember not to push it down again (I did!)

On your parking brake assembly is a single wire switch. You can unplug it, but you will have to remember not to drive with it set. To replace the switch the whole assembly will have to come out. The switch is about $20 and labor should run about two hours. Good Luck

you either have air in the brake lines, a cracked brake line, or low of brake fluid... either way you will need to bleed the brakes

have you had the brake pads changed recently?

probably need to adjust the cables

Parking Brake Cable Adjustment Vehicle with low series floor console

1. Remove the floor console front finish panel.
   1. If equipped, remove the manual transmission shift knob by turning counterclockwise.
   1. Remove the floor console front finish panel.

1. Remove the floor console rear finish panel.
   1. Apply the parking brake.
   1. Remove the floor console rear finish panel.

Vehicle with high series floor console

1. Remove the floor console finish panel.
   1. Apply the parking brake.
   1. Remove the floor console finish panel.

All vehicles

1. Remove the adjustment nut clip.

1. Turn the parking brake control adjustment nut so that the parking brake control stroke is three to five notches when pulled.

1. Confirm the parking brake is applied.

1. Install the adjustment nut clip.

Vehicle with high series floor console

1. Install the floor console rear finish panel.

Vehicle with low series floor console

1. Install the floor console rear finish panel.

1. Install the floor console front finish panel.
   • If equipped, install the manual transmission shifter knob by turning clockwise.

Hello;
The parking brake cables may be stretched and in need of adjustment. Follow the cables along to a nut. Then you can tighten the adjusters up on both sides until you have the proper tension. Also make certain none of the brackets are bent or broken that the cables ride through.
Thanks;
RPM Northwest

If they rebled the brakes and the pedal goes to the floor, chances are that the master cylinder is bad. Probably cost about $80-100 for the part if you could do it yourself