1999 Oldsmobile silhouette brake light and tcs

have the OBD codes read , sounds like low brake fluid or the brake pads need replacing, the OBD codes will tell you where to get started

If the brakes are spongy you will have to bleed the brakes again. It sounds like there is still air in them.
If you are doing it manualy make sure that the pedal is held down until the bleed screw is tight.
There is a brake bleeding kit that can be bought, this makes the job a lot easier.

Lets hope this has only been going on for a couple of days

Now you need to stop & have the vehicle checked for the codes
that set the lights,have those indicators diagnosed and whatever
needs to be repaired taken care of

For the future
Any light on the dash, is no different from the last one
They are all Govt Mandated Emission Faults, that need
attention in a couple of days.
They have been with us for 30 years now, and still
not understood,can't imagine why.

Both your issues are Braking System Problems
Not the brakes themselves as you know them
Electrical Issues not hydraulic or mechanical

ABS - antilock braking system
TCS - traction control system

If the warning light is on then there is a fault in the system, usually one of the sensors on each of the wheel hubs that measure the speed of the wheel.

It can still be the brake light switch,bypass the switch,and see if the lights will come on.

It's the " traction control system " that's off line, if you also have the [ Yellow ] Anti-lock Brake System light on, it usually means you have a problem with that system. The Traction control system is tied into that system. You should have the systems scanned.
good luck.

The humming noise is probably caused by a bad bearing hub assembly which also caused the abs and tcs light to come on. Does this only make the noise when the lights are on and vehicle is not moving or just when vehicle is moving?

The brake light may be on because of low fluid.The traction control is on because the abs light is on.System requires the abs to be actively working for traction control to work.The most common cause of this is a wheel speed sensor which on this vehicle is part of the bearing hub assembly.You will need a scan tool to locate where the fault is in the abs system.

The front pads are worn down which makes the brake fluid fill up the void the brake pads are missing now due to wear. Replace the brake pads and brake rotors if the rotors are worn too, then top off the brake fluid if needed. You can top of the break fluid for now, but that's just going to turn off your break light warning till you breaks wear it self down to the point you damage the brake rotors.

Have the brake pads replaced and inspect the brake rotors, if your good with common tools you can do this job your self in under 1 hour. Tools you need is a jack, 15mm socket, ratchet, screw driver and a clamp. The Clamp is optional, you can get the brake pads at Auto Zone and they can give you the step by step instructions to getting the job done. Keep me posted, be glad to answer any questions you may have and good luck.