Hello! I have a 2003 4Runner with 240K miles. 2 wheel drive. Recently, the emergency brake light lit up along with a constant beep.

The mechanic that I have gone to for quite some time only ran the codes it was throwing, and said I need to spend $3K on a new ABS Actuator. Everything I have read online says that when this fix was done, the problem happened again after a few weeks. Is it possible that the sensors are dirty or bad? Or possibly out of brake fluid?

The mechanic did not tell me if any of this was checked and said he was not willing to troubleshoot the issue. Very disappointing as I have been going there for 5 years. Having it towed to a new mechanic tomorrow who seems more willing to troubleshoot.
Any suggestions or experience with this issue?

Firstly, take a peek at the sensors for any dirt or damage, like you mentioned. Additionally, ensure the wheel speed sensor rings are intact and free from debris.

Next, examine the brake fluid level and condition. Low brake fluid or contaminated fluid can trigger ABS warnings. Check for any leaks in the brake system as well.

Considering the mileage, it might also be prudent to inspect the overall condition of the brake system components, such as the master cylinder and brake lines.

Also, don't overlook the electrical connections tied to the ABS. Loose or corroded connections might be giving you false readings.
The ABS pump motor relay could be causing trouble. Test and inspect the relay for any signs of wear or malfunction.

How is braking action and pedal pressure? Is system holding brake fluid? Are there any noises from the booster unit? Loud screech is bad pump motor. Constant pump running and sighing sound is leaking accumulator. There is also a pressure sensor that can go bad.

This is my 4Runner:

2003 Toyota 4Runner Brake Booster Noise C1223 and C1252 - YouTube

Replaced pump/accumulator with a junkyard example from '04 GS300 for $50.