I have a 2003 GMC Savana Van. The brake light came on and the brake alarm rings continously but will stop if I hit a bump (and then start again if I hit another one). I'm thinking a loose wire but several brake shops have not been able to find anything. Help! The noise is driving me crazy!

If someone took the time to look at the electrical schematic you will see several grounds in the circuit My first place I would go would be to check all the Grounds and Connections for the Brake Fluid level control, Brake Warning Indicator
The Instrument Panel Cluster (IPC) illuminates the brake warning indicator when one or more of the following occurs:

• The body control module (BCM) detects that the park brake is engaged. The IPC receives a class 2 message from the BCM requesting illumination.
• The electronic brake control module (EBCM) detects a low brake fluid condition. The IPC receives a class 2 message from the EBCM requesting illumination.
• The electronic brake control module (EBCM) detects a closed brake pressure differential switch. The IPC receives a class 2 message from the EBCM requesting illumination.
• The EBCM detects an ABS malfunction which disables dynamic rear proportioning (DRP) . The IPC receives a class 2 message from the EBCM requesting illumination.
• The IPC detects a closed power brake booster alarm switch and closed power brake booster fluid flow alarm switch. The IPC illuminates the brake warning indicator and sends a class 2 message to the radio requesting the brake warning alarm.
• The IPC performs the bulb check at the start of each ignition cycle. The brake warning indicator illuminates for approximately 3 seconds before turning OFF.
• The IPC detects a loss of class 2 communications with the BCM or with the EBCM.

• The Body Control Module (BCM) detects that the park brake is engaged. The IPC receives a serial data message from the BCM requesting illumination. The brake warning indicator flashes at a rate of approximately twice per second when the park brake is engaged.
• The EBCM detects a low brake fluid condition or base brake pressure differential and sends a serial data message to the IPC requesting illumination.
• The IPC performs the bulb check.
• The EBCM detects an ABS-disabling malfunction which also disables Dynamic Rear Proportioning (DRP) and sends a serial data message to the IPC requesting illumination.

All old rentals have an anti tampering device install on the speedometer sensor to prevdnt disconnecting miles shen the vehicle was rented. That will cause all kinds of trouble when it goes bad, makes noises, lights come on, shifts funny, etc etc all to make the person who tampered with it think he screwd something up so he reconnects it. I would check that device or bypass it comepletly