1981 corvette stingray the brake light has come on and stays on.The oil is ok as is the brake pads are good would it be the booster?

When the brake booster light and brake light come on after replacing the batteries in a 2017 Isuzu NPR Diesel, it could indicate a problem with the brake system or a malfunctioning brake booster.
Here are some steps you can take to troubleshoot the issue:

1. Check the brake fluid level: Low brake fluid level can cause the brake booster light and brake light to come on. Open the hood and check the brake fluid level in the reservoir. If the level is low, top it up with the recommended brake fluid and check if the lights go off.
2. Check the brake system: Inspect the brake lines, brake pads, and brake rotors for any damage or wear. If the brake pads are worn out, replace them immediately.
3. Check the brake booster: The brake booster is responsible for increasing the force applied to the brake pedal. Check the brake booster for any damage or wear. If the brake booster is malfunctioning, it will need to be replaced.
4. Reset the brake booster light: If the brake booster light and brake light stay on even after checking the brake fluid level and inspecting the brake system, it may be necessary to reset the brake booster light. To reset the brake booster light, turn the ignition switch to the "on" position without starting the engine. Pump the brake pedal 3 times, then turn the ignition switch off. Start the engine and check if the lights go off.

If none of these steps work, it is recommended to take the vehicle to a certified mechanic or the nearest Isuzu dealership for a professional diagnosis and repair.

lights must be connected to a circuit that does not run thru ignition switch.

You can order the heater core at any Auto Supplier
that specializes in A/C, heater,radiator,etc parts,also
maybe an auto parts store

I will be sarcastic here. Anyone owning a corvette, should
be doing their own work

If I could buy a stingray brand new, at age 19 & do a frame up
restoration,bore the old 327 & sleeve it at 22, & rebuilt the trans,
without any help or knowledge,you should be able to install
a heater core.

The air leak you hear is vacuum leaking from booster and also the hard pedal is also due to the booster, replace the vacuum brake booster and this will solve your problem. good day.

you have to bleed system

hey there
'is there any brake pads left
could need bleeding
could need a brake booster

The light comes on to to let you know there is low pressure in the system. If the fluid was extremely low when you filled it the brake linings are extremely worn or you have leak in the system. I would check under the car for any signs of moisture around the brake lines. If your brake linings are good and no leaks can be found you will need to replace the master cylinder. Good luck

you will have to remove the master cyl no need to dissconnect the lines and dissconnect the vacuume line and from inside the car under the dash dissconnect the brake pedal from the shaft running to the booster. and remove the 4 mounting bolts that hold the booster to the firewall and pull foward in the engine compartment.
as long as you dont dissconect the brake lines you wont need to bleed the brakes.
good luck
paul

Many possibilities but the alternator is a good place to start, if its plug is loose, then the green relay inside the center console just to the left and slightly in front of the emergency brake will be clicking in connecting and disconnecting the battery( one loud click per time). It will need replacing or simply disconnecting works for the short budget.

Most likely your vacumn power brake booster has failed. It is not rebuildable. You will need to buy a new one.