Sometime when driving, the parking brake indicator light on the instrument panel will light as well as the Parking Brake symbol displayed on the digital dash, accompanated by a buzzer. It will periodically flash on and off. Sometimes this will last for 5 minutes. Sometimes it will go on for 30 minutes, and sometimes the truck will go for 2 weeks without this problem occuring at all. I found the parking brake pressure switch and dissconnected the electrical connection to it but the problem continues. This is a 2006 Volvo Truck VNL780 Highway Tractor,

NOT ABS lamp , right?
the parking brake is adjusted first pre the service manual then
the switch must be adjusted to for closure brake released;
i use volt meter that switch after install and make sure it works
if not RTM read the service manual , on topic

this care is ODD
see this chapter in the service manual if opted day1.

Electronic Parking Brake Description tip if ice berg

Vehicles with the electric parking brake have a switch in the center console, which takes the place of the manual parking brake system, the foot pedal and release handle. In case of insufficient electrical power, the electric parking brake cannot be applied or released.
Occasionally, the electronic parking brake will automatically apply when the vehicle is not moving. The electronic parking brake performs a operational check every 50 key cycles. When this check is being performed, the park brake light on the instrument cluster becomes illuminated. This function does not affect the normal operation of the vehicle.
Electric Parking Brake Control Module The parking brake control module has an internal motor, apply actuator, release actuator, and temperature sensor. The parking brake control module also contains the logic for applying and releasing the parking brake when commanded by the park brake control switch. When the parking brake control module receives a signal from the switch the internal circuit board temperature is checked to verify it is within operating range before the control module performs the requested operation.
The electric parking brake module receives hard wired signals from the apply/release switch and communication enable. The electric parking brake module receives wheel speed sensor signals, engine torque, gear information, brake pedal signal, and etc. through GM-LAN.

AND MORE, LOTS MORE, READ THE MANUAL
PAY LIKE i MUST.

https://eautorepair.net/Marketing/Default.asp

They are in a closed loop the ABS and the balance pressure switch. You likely have some kind of problem with ABS system .If one dosn't work it will effect the other light

PRE-DIAGNOSTIC INSPECTIONBefore diagnosing ABS/TCS, perform a comprehensive visual inspection of system as follows.Check ABS/TCS wiring harness connectors for looseness. Check harness routing; pay particular attention to wheel speed sensor wiring harness routing. Check fuses No. 1D, 5B and 6B in instrument panel fuse block. Check fuses No. 1 and 2 in underhood fuse block. Check brake fluid level in master cylinder reservoir. Check brake fluid level in Pressure Modulator Valve (PMV) assembly reservoir. Ensure parking brake is fully released. Ensure parking brake switch is functioning properly. Always perform ABS/TCS system functional check before using DIAGNOSTIC CODE CHARTSThe EBCM/EBTCM has self-diagnostic capability, which can detect system failures. Fault codes stored by EBCM/EBTCM can be displayed using Tech 1 scan tester. There are no provisions for flash code diagnostics.Begin ABS/TCS diagnosis with PRE-DIAGNOSTIC INSPECTION procedure. If failures are found during pre-diagnostic inspection, perform necessary repairs, and proceed with ABS/TCS FUNCTIONAL CHECK. See Fig. 5 .If no failures are found during pre-diagnostic inspection, go to ABS/TCS FUNCTIONAL CHECK. See Fig. 5 . The ABS/TCS FUNCTIONAL CHECK will either indicate ABS/TCS is functioning properly or direct technician to various diagnostic procedures such as diagnostic charts, symptom diagnosis or BRAKE warning light diagnosis.CHART D - TRACTION OFF WARNING LIGHT ON CONTINUOUSLY & NO DTC SET (BUICK WITH UH8 OR U2A INSTRUMENT CLUSTER)Circuit DescriptionWhen ignition switch is first turned to RUN position, EBTCM goes through a self-test, which lasts 2-4 seconds. During self-test, EBTCM commands TRACTION OFF indicator warning light on. Powertrain Control Module (PCM) can also command EBTCM to set a Code 75 which will illuminate TRACTION OFF indicator.Traction control switch is located either on instrument panel center trim plate or driver's front door trim panel. Switch allows driver to select traction control mode (on/off). When traction control system is turned off, TRACTION OFF warning light comes on.EBTCM monitors transaxle temperature through

From Fiat LOW Brake Fluid / Parking Brake Either the exclamation mark symbol or the 'BRAKE' dashboard symbol may be used on various models of the Fiat 500. Light should illuminate until engine has started. If light remains on, it signifies the parking / hand brake is on, or that there is insufficient brake fluid in the reservoir. If light illuminates and the handbrake is not applied, braking may become defective. Seek assistance from a Fiat technician immediately.

Check to make sure your parking/hand brake is fully released, sometimes the spring that pushes back on the mechanism isn't strong enough, doesn't push back all the way, and the brake indication switch isn't engaged.
The other possibilities are that the float in the master brake cylinder is stuck (if it has one), or the level sensor has failed.

The light is not only used to indicate that the parking brake is on, but also indicates that there is a problem with the braking system. Make sure your brake fluid is topped off.

I have the same problem few days ago, and still didn't find any solution. Can any one please help?????18

Bulletin from Jaguar :

Electronic Park Brake (EPB)
Re-Calibration Procedure
2003 MY-ON
S-TYPE
M44998-ON

Issue:
On some 2003 MY-on S-TYPE vehicles, a customer may report a concern of premature
parking brake pad wear or the brakes binding. This condition can result if the electronic
park brake (EPB) system is not re-calibrated after the removal of the rear brake callipers
to replace the brake pads.
Action:
Should a customer express concern regarding the above, refer to the calibration
procedure detailed in this bulletin.

1. Reset the EB module:
a. Switch off the ignition.
b. Disconnect the battery for 30 seconds. For additional information, refer to STYPE
Workshop Manual Section 414-01.
c. Reconnect the battery.
2. Start the engine.
3. Firmly apply and release the foot brake five times.
4. Confirm that the message NOT CALIBRATED" or APPLY FOOT AND PARK
BRAKE" is displayed on the instrument cluster message center. This indicates that
the parking brake is in calibration mode.
5. Lightly press the foot brake pedal.
6. Apply the parking brake by using the EB switch.
7. Release the parking brake.
8. Release the foot brake.
9. Confirm that the brake warning lamp is no longer illuminated on the instrument
pack and that the NOT CALIBRATED" message is no longer displayed in the
message center.
10. Apply and release the EPB five times to ensure no error is present.
_____________________________________________________________________________

NB: It is also possible the actuator is bad though.

If the ! symbol you saw is inside a circle enclosed in parentheses like (O), and usually red in color, that's for your brake fluid. Check it out, maybe its low on fluid. If it is, check for fluid leaks or worn brakepads. Usually the ! symbol coincides with the P symbol and also red in color. When the park brake is engaged, both these symbols appear together. If you release the park brake, both indicators should turn off under normal conditions, otherwise either of the two or both will stay on when there is insufficient fluid or there's a parking brake circuit fault. Brakes are very important, so give proper attention and solution if ever these indicators lightb up when they shoud not.
If the ! symbol is very bold and inside a half drawn flat tire, and yellow in color, thats the tire pressure monitor indicator. Check and balance all four tire pressures to the correct specification.
Okay, sir? have a safe trip. : )

inset the key and switch on to position 2
Scroll through the warning display untill you get the service indicator apears
Press and hold the reset button on the left of the dash apnel for about 4 mins
You will be asked if you want to reset
Press anh hold the reset button again until you hear an audible warning
It should now show the new interval to a service