AUTOMATIC FRONT SAFETY BELT TENSION RELIEF DEVICE FUNCTION
MODELS AFFECTED: 1990 BUICK LESABRE AND ELECTRA/PARK AVENUE
For the 1990 Model Year, the 1990 Buick LeSabre and Electra/Park Avenue with automatic safety belts have retained a shoulder belt tension relief mechanism (comfort feature). However, the mechanism for setting and cancelling the shoulder belt tension relief mechanism changed in 1990 and is different from the 1987-1989 Model Years.
In order to understand the different operation, first review how the 1987-1989 system works:
1987 - 1989 MODEL YEAR
SETTING SHOULDER BELT COMFORT FEATURE
1. Sit in the seat and close adjacent door.
2. Buckle the necessary seat belt.
3. Pull the shoulder belt out at least 130 mm (5 inches) and let it return. The belt should go back to your chest.
4. Pull out the shoulder belt again, about 25 mm (1 inch) and let the belt go. The tension relief device should engage and the shoulder belt should not retract.
CANCELLING SHOULDER BELT COMFORT FEATURE
1. Open the adjacent door. This allows a plunger on the door, (just below the door latch), to push outward and cancel the comfort feature.
2. The "Webbing Pull" method. Pull out approximately 130 mm (5 inches) of shoulder belt and return. This resets the system and cancels the comfort feature.
For the 1990 Model Year, the plunger cable control mechanical system has been replaced with an electronic system and the following information applies:
1990 MODEL YEAR
SETTING SHOULDER BELT COMFORT FEATURE
1. Both front doors must be closed for approximately 5 seconds. This delay is because the solenoids used for the tension relief device are electrically connected with the timer used to reset the system. An audible "click" may be heard when the solenoids release.
2. From this point the tension relief setting procedure is the same as model years 1987-1989.
CANCELLING SHOULDER BELT COMFORT FEATURE
1. For the 1990 model automatic safety belts the "Webbing Pull" method will cancel the comfort feature. This is the same as model years 1987-1989.
2. A new method for cancelling the comfort feature uses the shoulder belt retractor solenoid. The solenoid that engages the block out system also cancels the comfort feature. All four solenoids in the safety belts are activated if either door is opened. So when either front door is open, the comfort feature in both shoulder belts is cancelled. To trouble shoot the cancelling features of the tension relief mechanism, see the attached diagram (Appendix A).
Th 1990 system also contains the following features:
BLOCK OUT
IMPORTANT: THE BLOCK OUT MECHANISM HAS BEEN ON AUTOMATIC SAFETY BELTS SINCE THEY BEGAN IN THE 1987 MODEL YEAR.
When the safety belts are used as intended (i.e. always attached to the inboard lap belt buckle) the action of opening the door to enter or exit the vehicle can result in accelerations high enough to cause the retractors to lock up. This would keep you from opening the door fully. The "block out" energizes a solenoid mechanism in each retractor so it now takes significantly higher accelerations to lock up the safety belts when the door is opened.
VEHICLE SPEED SENSING
A new feature of the safety belt system for the 1990 Model Year is the use of the vehicle speed sensor (VSS). If the car is traveling at 2 mph or greater, the solenoids will no longer energize if the door latch is activated. This keeps the retractor at a higher sensitivity.
"FASTEN BELT" LIGHT SWITCH OPERATION (INCLUDING MANUAL SAFETY BELTS)
Prior to 1990 the switch to turn the "Fasten Belts" light off was in the driver's inboard belt buckle. For 1990 the switch has been moved to the driver's lap belt retractor. The switch is deactivated after 6 to 12 inches of lap belt webbing is extracted.
Additionally, if a customer comments on a 1990 vehicle that his passenger or driver safety belts sometimes do not retract normally, follow the diagnostics shown in Appendix A and be sure to conduct the following checks:
1. Check the tension relief device for proper operation. Use the procedure for setting and cancelling the comfort feature described previously.
2. Check the operation of the lap and shoulder belts for proper retraction. If any of the safety belts are "sluggish" compared to the others, the safety belt assembly should be replaced.
3. If no problems can be detected with the safety belts, the Solenoid Timer Module may need to be replaced with an enhanced minimum time delay module, Part Number 25557059. The new module (part number 25557059) is in all Buick LeSabres with VINS LH474249 or greater and Buick Electra Park Avenues with VINS L1644969 or greater.
The Timer Module is described on:
Page 368, Buick LeSabre, Park Avenue/Electra Electrical Service Manual
4. Replace any damaged belt assemblies that appear torn or frayed.
5. For any safety belts soiled, use mild soap and water to clean.
Parts are currently available from GMSPO.
General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.
