I understand why dealership mechanics hate troubleshooting on modified cars. They can be a black hole for time because they don't know what nasty surprises lurk and the service manager hates having to deal with the customer who gets the bill for the hours associated with the nasty surprises. If you have a modified car, you should be prepared to 'own' all aspects of that car. Time to get a service manual!That said, there are three things on a stock NSX that can cause the brake system light to come on:- the parking brake switch- operation of the fluid level switch in the brake reservoir- a short to ground in the wiring associated with the parking brake switch or the brake reservoir level switchThe ABS system uses the same circuit to detect engagement of the parking brake. If the ABS system receives a signal that the parking brake is engaged (because the brake system light is on) it will deactivate the ABS which is why your ABS light is on. I expect the TCS is getting the same erroneous signal causing the TCS light to come on. I expect (but did not check) that you have no ABS or TCS codes because there is nothing wrong with those systems.First the easy stuff. Check the operation of the switch on the parking brake lever to make sure that it has not come out of adjustment and is still remaining slightly closed when the lever is released. Operate the switch manually a few times to make sure that it is not sticky. Check the wiring to the parking brake switch to look for an obvious short to ground. Check the fluid level in the brake reservoir to make sure that it has not dropped to the point where the level switch is just starting to close. Pull the cover off the brake reservoir and operate the level switch a few times to make sure that it is not hanging up. Check the wiring to the level switch to look for a short.Now the hard stuff. If the previous two steps don't yield anything, disconnect the parking brake switch and the brake reservoir level switch. If the brake system light remains on, then you almost assuredly have a short to ground somewhere in the wiring for the brake system light. You will need to get the electrical section of the service manual so you can find the connector numbers that will tell you which wiring harness that circuit runs through. Be prepared for a deep dive into and under the dash.I have no clue what your beep might be. I don't think anything on my 2000 'beeps' other than the key-in door chime and the seat belt reminder. By chance, do you have an after market security system? If so, some systems have a tie in to the parking brake switch for programming purposes. If it does your security system may have a partial failure or a wiring problem causing the problem for the brake system circuit.
