Seat belts no front seat belt chimes or indicator (on dash)

spontaneously alerts ??? Warning chimes Warning Devices The warning device system consists of the following:

• Key-in-ignition warning switch
• Door ajar switch
• Driver and passenger safety belt minder switch (integral to the safety belt buckle)
• Vehicle security module

The instrument cluster and the restraints control module (RCM) control the following chimes:

• Safety belt warning (repetitive chime)
• Key-in-ignition warning (repetitive chime)
• Headlamps on warning (repetitive chime)
• Door ajar warning (single tone)
• Air bag warning (repetitive chime) The following 5 distinct chime rates are used to indicate warning:
  
  • safety belt warning is 1 chime per second
  • key-in-ignition warning is 2 chimes per second
  • headlamps on warning is 4 chimes per second
  • door ajar warning is a single chime
  • air bag warning is 5 chimes per second
  • now which of these is your vehicle doing ?

Under the dash on the left hand side but if there was a wire plug on old seat buckle should be able to loop circuit together so acts like seat belt is always hooked

disconnect that sucker from under the seat. Look under the seat ( move it all the way forward it will easier) find the seat belt buckle there will be a wire coming off it. follow the wire to the connection then disconnect it. no more chime. or light on the dash either

I’m happy to help further over the phone at https://www.6ya.com/expert/dennis_7c5f8bf265aab5e9

The seat belt warning chime is controlled by the central timer module ! You can't just disconnect fuses , other things may stop working !
Safety Belt Warning Indicator Lamp and Chime
The safety belt indicator and chime feature is controlled by the CTM. The driver safety belt switch is hardwired to the CTM. If at any time during the first 60 seconds after the ignition switch is placed in position II, if the driver safety belt is sensed as being unfastened, the CTM will process the input, and in turn, output a signal to the CTM through a hardwired circuit. In turn the CTM will output a visual warning to the instrument cluster. If at any time during the first six seconds after the ignition switch is place in position II and the safety belt is not fastened, the safety belt warning chime will sound.
When the seat belt is connected the warning still chimes ? Could have code stored in the CTM .
B1464 Safety belt switch circuit short to battery CTM Go To Pinpoint Test B .
SoW

The warning chime sounds if the parking lamps (13200) or the headlamps (13008) are left on after the key has been removed from the ignition switch lock cylinder and either front door (20124) is opened. There is a chime module that controls this .
The safety belt warning chime (10D840) (also called the central processing unit or CPU) is an audible warning system and timing circuit. The system components include:

• Timing circuit safety belt switch.
• Dome lamp switches.
• Safety belt warning indicator switch which is an integral part of the front safety belt buckle end (61203).
• Ignition switch (11572).
• Headlamp switch.

The warning chime sounds and the safety belt warning indicator illuminates when the ignition switch is placed in the ON position and the LH front safety belt is not buckled.
Key In Ignition Warning
The warning sounds if the key is left in the ignition switch lock cylinder when either door is opened and the ignition switch is in the LOCK or OFF position.
Don't any of chimes work ?

• The Headlamp on Reminder Chime Is Inoperative/Does Not Operate Properly

• Circuits.
• Fuse junction panel.
• Warning chime module.

• GO to Pinpoint Test D .

Let me know ,mite work this out !
Don't

Try under dash, Drivers side, Left side near side of car at firewall

The audible warnings alert the driver of a system concern or a critical vehicle condition. The radio generates the audible warnings through the left front speaker. The radio receives audible warning requests via the class 2 serial data line from the IPC or body control module (BCM). If the radio receives multiple audible warning requests, the warning with the highest priority sounds first. The following lists the audible warning priority and the pulse rate:
Fast rate chime--200 pulses per minute
Medium rate chime--150 pulses per minute
Slow rate chime--50 pulses per minute
Single chime

Is the sound heard different from typical Audible Warnings ?

Fasten Safety Belt Warning
The radio activates the fasten safety belt audible warning as requested by the IPC. The IPC sends a class 2 message to the radio indicating the chime frequency, slow rate and duration (5 pulses). The fasten safety belt warning sounds and the fasten safety belt indicator illuminates when the following occurs:
• The ignition switch transitions to ON.
• The inflatable restraint sensing and diagnostic module (SDM) detects that the driver's seat belt is not buckled, signal is low. The IPC receives a class 2 message from the SDM indicating the driver's seat belt status.
If the seat belt is buckled when the ignition is turned on, the chime does not sound. If the seat belt is buckled while the chime is sounding, the chime stops. If the seat belt is unbuckled after the initial transition to ON, the chime does not sound.
Headlamps On Warning
The radio activates the headlamps on warning as requested by the body control module (BCM). The BCM sends a class 2 message to the radio indicating the chime frequency, fast rate and duration, continuous. The headlamps on warning sounds when the following occurs:
• The ignition is OFF.
• The BCM determines that the driver's door is open, signal is low.
• The BCM determines that the headlamp switch is in the park or head position.
Key-In-Ignition Warning
The radio activates the key-in-ignition audible warning as requested by the BCM. The BCM sends a class 2 message to the radio indicating the chime frequency, medium rate and duration, continuous. The key-in-ignition warning sounds when the following occurs:
• The ignition switch is OFF.
• The body control module (BCM) determines that the driver's door is open, signal is low.
• The BCM determines that the key-in-ignition switch is closed, signal is low.
Turn Signal Reminder
The radio activates the turn signal warning as requested by the IPC. The IPC sends a class 2 message to the radio indicating the chime frequency, medium rate and duration, continuous. The turn signal warning sounds when the following occurs:
• The ignition switch is in the RUN position.
• The turn signal switch is in either turn position, sensing, within 1 second, an open to B+ transition in the turn signal control circuit, left or right turn.
• The vehicle has traveled a distance of 1.2 km (¾ mi) by counting pulses on the vehicle speed input circuit.
The IPC turns OFF the turn signal reminder when either the ignition switch is turned to the OFF position, or the turn signal switch returns to the OFF position, sensing, within 1 second, no transitions from open to B+ in either of the turn signal control circuits, left turn or right turn.
Additional Chimes
The following chimes will turn ON when an associated indicator/message turns ON in the IPC/DIC:
• ABS indicator
• AWD Disable indicator
• Battery/Charge indicator
• Brake indicator
• Change Engine Oil indicator
• Door Ajar indicator
• Hot Coolant Temp indicator
• Low Brake Fluid indicator
• Low Fuel indicator
• Low Oil Level indicator
• Low Oil Pressure indicator
• Low Tire Pressure indicator/reset
• Low Washer Fluid indicator
• MIL (Service Engine Soon) indicator
• Oil Life Reset
• Park Lamp Out indicator
• Rear Hatch Ajar indicator
• Service Traction System indicator
• Service Vehicle Soon indicator
• TRAC OFF indicator
For a description of an indicator refer to Indicator/Warning Message Description and Operation .
For diagnosis of an indicator refer to Symptoms - Instrument Panel, Gages and Console .

Did the Mechanic check for DTC'S - diagnostic trouble codes in the BCM or insturment cluster ? Did you try a Buick dealer ?

Section 13-09: Gauges, Warning Devices — Chime System 1996 Windstar Workshop Manual
DESCRIPTION AND OPERATION Warning Chime Systems Three distinct sounds are used to indicate the area of concern. Seat belt warning generates 1 chime per second
key-in-ignition generates 2 chimes per second
headlight on generates 4 chimes per second.
Key-In-Ignition Warning The key-in-ignition warning will sound when the driver's front door (20125) is opened with the key in the ignition switch. It will continue to sound until the key is removed, the front door is closed, the ignition switch is turned to START or the vehicle speed is over 24 kmh (15 mph).

Safety Belt Warning When the ignition switch is turned to RUN or START from OFF or ACC, the chime will sound for six seconds or until the safety belt is buckled.

• The safety belt warning indicator lamp (10C859) will activate for 60 seconds or until the driver's safety belt is fastened. Both the chime and lamp activate at the same time.

Anytime the ignition switch is released from START and returns to RUN while the safety belt lamp or chime is activated, the safety belt warning lamp or chime will remain activated until either the timing sequence has been executed, or the safety belt is buckled.

Headlamp Switch On Warning The chime will be activated if the headlamps or parking lamps are ON, the key is not in the ignition and the driver's door is opened. The chime will sound at a rate of four per second.

Q: Are you wearing your seat belt? Yes? No?

A: No.
Solution: Put on your seat belt!!!!!! Save a life!!!

A: Yes.
Soultion: There has to be a fuse either under the dash or under the hood that controlls the chime.
There is a switch in the seatbelt connecter that controlls the chime. It has either failed or the wireing that carried the signal to shut the chime off has been damaged.

you could push some thing into the female end like an old blockbuster card or equivelent to depress the switch inside so it thinks your seat belt is on