GM Century/Lumina/Grand Prix/Intrigue 1997-2000

General Information

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The Supplemental Inflatable Restraint (SIR) system (also called the air bag system) helps supplement the protection offered by the driver and front passenger seat belts by deploying an air bag from the center of the steering wheel and from the top of the right side of the instrument panel.

The air bag deploys when the vehicle is involved in a frontal crash of sufficient force up to 30 degrees off the centerline of the vehicle. To further absorb the crash energy there is a knee bolster located beneath the instrument panel for both the driver and the passenger, and the steering column is collapsible.

Beginning in 2000, side impact air bags were introduced on selected models. The side impact air bag system consists of the following additional components that interface with the inflatable restraint Sensing and Diagnostic Module (SDM):



An inflatable restraint Side Impact Sensor (SIS) inside the driver side B-pillar (also called the door post).
 
An inflatable restraint front side impact module in the driver's seat.
 



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Fig. SIR system "deployment window"



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Fig. The SIR system components, when used with a seat belt/shoulder harness, can provide additional protection during an accident



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Fig. Introduced on some 2000 vehicles, the side impact air bags are designed to further enhance the effectiveness of the vehicle's air bag system

SYSTEM COMPONENTS



The SIR system consists of the following components:



An inflatable restraint Sensing and Diagnostic Module (SDM)
 
An inflatable restraint steering wheel module (driver's side air bag)
 
An inflatable restraint steering wheel module coil
 
An inflatable restraint instrument panel module (passenger side air bag)
 
An inflatable restraint side impact module (selected 2000 models)
 
An AIR BAG warning lamp in the instrument cluster.
 

Sensing and Diagnostic Module (SDM)


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Fig. Mounting location for the air bag Sensing and Diagnostic Module (SDM)

The inflatable restraint Sensing and Diagnostic Module (SDM), inflatable restraint steering wheel module coil (SIR coil assembly), inflatable restraint steering wheel module (driver inflator module), inflatable restraint instrument panel module (passenger inflator module) and connector wires make up the deployment loops. The function of the deployment loops is to supply current through the inflator modules, which will cause deployment of the air bags. Deployment occurs when the SDM detects vehicle velocity changes severe enough to warrant deployment.

The SDM contains a sensing device (accelerometer) that converts vehicle velocity changes to an electrical signal. The SDM compares this electrical signal to a value stored in memory. When the generated signal exceeds the stored value, the SDM performs additional signal processing and compares the generated signals to values stored in memory. When two of the generated signals exceed the stored values, the SDM will cause current to flow through the inflator modules, deploying the air bags.

The SDM performs the following functions in the SIR system.



Energy Reserve-The SDM maintains 23 Volt Loop Reserve (23 VLR) energy supplies to provide deployment energy. Ignition voltage can provide deployment energy if the 23 Volt Loop Reserves malfunction.
 
Frontal Crash Detection-The SDM monitors vehicle velocity changes to detect frontal crashes that are severe enough to warrant deployment.
 
Air Bag Deployment-During a frontal crash of sufficient force, the SDM will cause enough current to flow through the inflator modules to deploy the air bags.
 
Frontal Crash Recording-The SDM records information regarding the SIR system status during a frontal crash.
 
Malfunction Detection-The SDM performs diagnostic monitoring of the SIR system electrical components. Upon detection of a circuit malfunction, the SDM will set a diagnostic trouble code.
 
Driver Notification-The SDM warns the vehicle driver of SIR system malfunctions by controlling the AIR BAG warning lamp.
 

The SDN connects to the SIR wiring harness using a 12-way connector. The SDM harness connector uses a shorting bar across certain terminals in the contact area. Removal of the SDM Connector Position Assurance (CPA) or the harness connector itself will connect the AIR BAG warning lamp to ground through the shorting bar.

The AIR BAG warning lamp will come ON steady with power applied to the SDM when either one of the following two conditions exist:



You remove the SDM CPA.
 
You disconnect the SDM harness connector.
 

The SDM receives power whenever the ignition switch is at the ON or START positions. In addition, the SDM can maintain sufficient voltage to cause a deployment for up to ten minutes after the ignition switch is turned to the OFF position, the battery is disconnected or the fuse powering the SDM is removed. Many of the SIR service procedures require removal of the "AIR BAG-1" fuse and disconnection of the deployment loops to avoid an accidental deployment.

AIR BAG Warning Lamp

The AIR BAG warning lamp indicates the words "AIR BAG" for domestic vehicles. For Canadian and some export models, the AIR BAG warning lamp is an icon graphic. The ignition switch applies ignition voltage to the AIR BAG warning lamp. The AIR BAG warning lamp receives power whenever the ignition switch is at the ON or START positions. The inflatable restraint SDM controls the lamp by providing ground with a lamp driver. The SIR system uses the AIR BAG warning lamp to do the following:



Verify lamp and SDM operation by flashing the lamp seven times when the ignition switch is first turned to the ON position.
 
Warn the vehicle driver of SIR electrical system malfunctions which could potentially affect the operation of the SIR system. These malfunctions could result in non-deployment in case of a frontal crash or deployment for conditions less severe than intended.
 

The AIR BAG warning lamp is the key to driver notification of SIR system malfunctions.

Inflatable Restraint Steering Wheel Module Coil

The inflatable restraint steering wheel module coil consists of two or more current-carrying coils. The inflatable restraint steering wheel module coil attaches to the steering column. Two of the current-carrying coils allow rotation of the steering wheel while maintaining continuous contact of the driver deployment loop to the inflatable restraint steering wheel module (the air bag itself).

There is a shorting bar on the yellow 2-way connector near the base of the steering column that connects the inflatable restraint steering wheel module coil to the SIR wiring harness. The shorting bar shorts the circuits to the steering wheel module coil and steering wheel module (air bag) during disconnection of the yellow 2-way connector. The shorting of this circuitry is designed to help prevent unwanted deployment of the air bag when servicing the steering column or other SIR system components.

Inflator Modules

The inflator modules consist of an inflatable bag and an inflator. An inflator consists of a canister of gas-generating material and an initiating device. The initiator is part of the deployment loop. When the vehicle is in a frontal crash of sufficient force, the inflatable restraint SDM causes current to flow through the deployment loops. Current passing through the initiator ignites the material in the inflator module. The gas produced from this reaction rapidly inflates the air bag.

There is a shorting bar on the inflatable restraint steering wheel module side of the upper steering column connector that connects the inflatable restraint steering wheel module coil to the inflatable restraint steering wheel module (air bag). The shorting bar shorts across the steering wheel module circuits during disconnection of the upper steering column connector. The shorting of the steering wheel module circuitry will help prevent unwanted deployment of the air bag when servicing the steering wheel module, the steering column or other SIR system components.

There is a shorting bar on the inflatable restraint instrument panel module (passenger side air bag) connector that connects to the SIR wiring harness. The shorting bar shorts across the inflatable restraint instrument panel module circuits during disconnection of the instrument panel module connector. The shorting of the instrument panel module circuitry will help prevent unwanted deployment of the air bag when servicing the instrument panel module, the instrument panel or other SIR system components.

Side Impact Air Bags

Introduced on selected 2000 models, the Side Impact Air Bag System is designed to further enhance the effectiveness of the vehicle's inflatable restraint system. The Side Impact Air Bag System supplements the protection offered by the driver door, the front passenger door, and the vehicle structure. The Side Impact Air Bag system deploys an air bag from the side of the driver or front passenger seat. A side crash of sufficient force will deploy a side air bag.

The inflatable restraint Side Impact Sensor (SIS), the inflatable restraint front side impact module and the connecting wires make up the side impact deployable loop. The function of the side impact deployment loop is to supply current through the side impact inflator module, which will cause deployment of the side impact air bag. Deployment occurs when the SIS detects a side impact severe enough to warrant deployment.

The SIS contains a sensing device (accelerometer) that converts acceleration into an electrical (analog) signal. This signal is converted by a microprocessor in the SIS into acceleration and velocity data. This data is used by a sensing algorithm and compared to various predetermined boundary conditions. When the acceleration value exceeds the predetermined threshold, and the velocity boundary is crossed, the SIS signals the SDM to cause current to flow through the appropriate inflatable restraint front side impact module, deploying the front side impact air bag.

SERVICE PRECAUTIONS



Special care is necessary when handling and storing a live (undeployed) inflator module (air bag assembly). If, for example, steering column service is required (turn signal switch, ignition lock repair, etc.) the air bag assembly must be removed for access. Caution is required. The rapid gas generation produced during deployment of the air bag could cause the air bag module, or an object in front of the air bag module, to be thrown through the air in the unlikely event of an accidental deployment.


CAUTION
When carrying a live inflator module (air bag), make sure the bag opening is pointed away from you. In case of an accidental deployment, the bag will then deploy with minimal chance of injury. Never carry the air bag module by the wires or connector on the underside of the air bag. When placing a live air bag on a bench or other surface, always face the bag and trim cover up, away from the surface. This is necessary so that a free space is provided to allow the air bag to expand in the unlikely event of accidental deployment. Never rest a steering column on the steering wheel with air bag face down and the column vertical. Otherwise, personal injury may result.



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Fig. Proper handling of a live inflator module



Do not expose the inflator modules to temperatures above 150°F (65°C).
 
Verify the correct replacement part number. Do not substitute a component from a different vehicle.
 
Do not attempt to repair the SDM, the inflatable restraint inflator module, the air bag, or the steering wheel module coil. Service these components by replacement only.
 
Use only new or remanufactured parts from an authorized original equipment manufacturer dealer. Do not use salvaged parts for repairs to the SIR system.
 
Discard the following components if they have been dropped from more than a height of 3 feet: the SDM , the inflatable restraint inflator module, the air bag, and the steering wheel module coil.
 
Never disconnect any electrical connection with the ignition switch in the ON or RUN position.
 
Avoid touching module connector pins.
 
Always wear a grounded wrist static strap when servicing any control module or component labeled with a Electrostatic Discharge (ESD) sensitive device symbol.
 



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Fig. This symbol indicates that a component is sensitive to Electrostatic Discharge (ESD)



Due to the complexity and critical nature of this system, it should only be serviced by an authorized technician with the proper test equipment. The components are expensive and easily damaged if the wrong equipment or techniques are used, resulting in a compromise of the system's ability to protect the vehicle's passengers and/or expensive and unnecessary component replacement.
 

DISARMING THE SYSTEM




CAUTION
When performing service on or around SIR components or SIR wiring, follow the procedures listed below to temporarily disable the SIR system. Failure to follow procedures could result in possible air bag deployment, personal injury or otherwise unneeded SIR system repairs.

The inflatable restraint Sensing and Diagnostic Module (SDM) maintains a reserve energy supply. When the vehicle power is insufficient to cause deployment of the air bags, the reserve energy supply provides the deployment power. Deployment power is available for as many as 10 minutes after disconnecting the vehicle power by any of the following methods:



You turn OFF the ignition switch.
 
You remove the AIR BAG fuse (also identified as SIR or SDM fuse) that provides power to the SDM.
 
You disconnect the vehicle battery from the vehicle electrical system.
 

Performing the following procedure prevents deploying of the air bags from the reserve energy supply power.

1997-99 Vehicles


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Fig. The air bag system fuse may be designated as AIR BAG , SIR or SDM fuse in the instrument panel fuse block



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Fig. Typical steering wheel electrical connections, including SIR Module leads



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Fig. Typical steering column electrical connections, including SIR Module leads



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Fig. Typical instrument panel (passenger side) air bag electrical connections



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Fig. Usually, these insulator panels must be removed to access the air bag connections

  1. Turn the steering wheel to the straight ahead position.
  2.  
  3. Turn the ignition switch to the OFF position and remove the key from the ignition switch.
  4.  
  5. Open the instrument panel fuse block access door. Locate and remove the AIR BAG fuse (it may also identified as SIR or SDM fuse, depending on the vehicle) from the instrument panel fuse block.
  6.  
  7. Remove the driver's side instrument panel insulator, a trim panel under the steering column. This normally requires a trim clip removal tool to detach the plastic panel retainers from the steering column opening filler panel. Disconnect the courtesy lamp, as required, by turning 1 / 4 turn counterclockwise.
  8.  
  9. On the driver's side, a yellow 2-way connector is located at the base of the steering column. First locate, then remove the Connector Position Assurance (CPA) pin. The CPA is a small wedge-shaped plastic piece designed to lock the connector together. With the CPA removed, detach the driver's side yellow 2-way connector.
  10.  
  11. To disable the passenger side instrument panel air bag, remove the instrument panel compartment door.
  12.  
  13. Remove the Connector Position Assurance (CPA) pin and separate the passenger's side yellow 2-way connector located behind the instrument panel door.
  14.  

2000 Century, Regal, Grand Prix and Intrigue
  1. Turn the steering wheel to center the front wheels in the straight ahead position.
  2.  
  3. Turn the ignition switch to the OFF position and remove the key.
  4.  


NOTE
With the AIR BAG fuse removed, if, for some reason, the ignition switch is turned to the ON position, the AIR BAG warning lamp illuminates. This is normal operation and does not indicate an SIR system malfunction.



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Fig. Major SIR system component locations, including vehicles with side impact air bags



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Fig. SIR system connector locations, including vehicles with side impact air bag module-2000 vehicles



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Fig. SIR side impact air bag module location in the front seat-2000 vehicles

  1. Remove the instrument panel fuse block access door.
  2.  
  3. Remove the AIR BAG fuse (may also be identified as a numbered fuse or as the SIR or SDM fuse) from the fuse block.
  4.  
  5. Remove the left instrument panel insulator, the trim panel under the steering column.
  6.  
  7. Locate and remove the Connector Position Assurance (CPA) pin which locks the connector together, and separate the driver side yellow 2-way connector located at the base of the steering column.
  8.  
  9. Locate and remove the Connector Position Assurance (CPA) pin which locks the connector together, and separate the passenger side yellow 2-way connector located to the right of the steering column.
  10.  
  11. On vehicles equipped with a driver's side impact air bag, the air bag is built into the side of the seat facing the door. Move the driver's seat back as far as possible to gain access to the driver side air bag yellow 2-way connector. Detach the driver's side impact air bag yellow 2-way connector.
  12.  

2000 Monte Carlo
  1. Turn the steering wheel to center the front wheels in the straight ahead position.
  2.  
  3. Turn the ignition switch to the OFF position and remove the key.
  4.  


NOTE
With the AIR BAG fuse removed, if, for some reason, the ignition switch is turned to the ON position, the AIR BAG warning lamp illuminates. This is normal operation and does not indicate an SIR system malfunction.

  1. Remove the left side instrument panel access hole cover.
  2.  
  3. Remove the AIR BAG fuse (may also be identified as SIR or SDM fuse) from the fuse block.
  4.  
  5. Remove the right side instrument panel access hole cover.
  6.  
  7. Unclip the frontal air bag's yellow 4-way connector from the metal rail.
  8.  
  9. Locate and remove the Connector Position Assurance (CPA) pin which locks the connector together, and separate the front air bag's yellow 4-way connector.
  10.  



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Fig. Disarm the SIR system by removing the fuse, then disconnecting the front air bag connector-2000 Monte Carlo

  1. On vehicles equipped with a driver's side impact air bag, the air bag is built into the side of the seat facing the door. Move the driver's seat back as far as possible to gain access to the driver side air bag yellow 2-way connector. Detach the driver's side impact air bag yellow 2-way connector.
  2.  

2000 Lumina
  1. Turn the steering wheel to center the front wheels in the straight ahead position.
  2.  
  3. Turn the ignition switch to the OFF position and remove the key.
  4.  


NOTE
With the AIR BAG fuse removed, if, for some reason, the ignition switch is turned to the ON position, the AIR BAG warning lamp illuminates. This is normal operation and does not indicate an SIR system malfunction.

  1. Remove the instrument panel fuse block access door.
  2.  
  3. Remove the AIR BAG fuse (may also be identified as Fuse 21, or SIR or SDM fuse) from the fuse block.
  4.  



Click image to see an enlarged view

Fig. Disarm the SIR system by removing the fuse and disconnecting the front air bag connector-2000 Lumina

  1. Remove the left instrument panel insulator, the trim panel under the steering column.
  2.  
  3. Locate and remove the Connector Position Assurance (CPA) pin which locks the connector together, and separate the driver side yellow 2-way connector located at the base of the steering column.
  4.  
  5. Remove the right side sound insulator from under the instrument panel
  6.  
  7. Locate and remove the Connector Position Assurance (CPA) pin which locks the connector together, and separate the passenger side yellow 2-way connector located behind the instrument panel compartment door.
  8.  

ARMING THE SIR SYSTEM



1997-99 Vehicles
  1. Remove the key from the ignition switch.
  2.  
  3. Attach the yellow 2-way connector located behind the instrument panel compartment door and insert the CPA to verify the connection is secure. Install the instrument panel compartment door.
  4.  
  5. Attach the yellow 2-way connector located at the base of the steering column and insert the CPA pin to verify the connection is secure. Install the driver's side instrument panel insulator.
  6.  
  7. Install the AIR BAG fuse (also identified as SIR or SDM fuse) to the instrument panel fuse block.
  8.  
  9. Staying well away from both air bags, turn the ignition switch to the ON position. Verify that the AIR BAG warning lamp flashes seven times and then stays off. If the AIR BAG warning lamp does not operate as described, an SIR Diagnostic System Check will be required at an authorized dealership. A scan tool is required to check out the SIR system.
  10.  

2000 Century, Regal, Grand Prix and Intrigue
  1. Remove the key from the ignition switch.
  2.  
  3. If equipped with a driver's side impact air bag:
    1. Move the driver's seat back as far as possible to gain access to the driver's side impact air bag yellow 2-way connector which is located under the driver's seat.
    2.  
    3. Attach the yellow 2-way connector and insert the CPA pin to verify the connection is secure.
    4.  

  4.  
  5. Attach the passenger's side yellow 2-way connector located to the right of the steering column and insert the CPA pin to verify the connection is secure.
  6.  
  7. Attach the yellow 2-way connector located at the base of the steering column and insert the CPA pin to verify the connection is secure. Install the driver's side instrument panel insulator.
  8.  
  9. Install the AIR BAG fuse (also identified as SIR or SDM fuse) to the instrument panel fuse block.
  10.  
  11. Staying well away from both air bags, turn the ignition switch to the ON position. Verify that the AIR BAG warning lamp flashes seven times and then stays off. If the AIR BAG warning lamp does not operate as described, an SIR Diagnostic System Check will be required at an authorized dealership. A scan tool is required to check out the SIR system.
  12.  

2000 Monte Carlo
  1. Turn the ignition switch to the OFF position and remove the key.
  2.  
  3. On vehicles equipped with a driver's side impact air bag, the air bag is built into the side of the seat facing the door. Move the driver's seat back as far as possible to gain access to the driver side air bag yellow 2-way connector. Attach the driver's side impact air bag yellow 2-way connector and install the CPA pin to verify the connection is secure.
  4.  
  5. Attach the frontal air bags yellow 4-way connector located at the right side of the instrument panel and install the CPA pin to verify the connection is secure. Attach the 4-way connector to the metal rail.
  6.  
  7. Install the right side instrument panel access hole cover.
  8.  
  9. Install the AIR BAG fuse (may also be identified as SIR or SDM fuse) to the left side fuse block. Install the instrument panel access hole cover.
  10.  
  11. Staying well away from both air bags, turn the ignition switch to the ON position. Verify that the AIR BAG warning lamp flashes seven times and then stays off. If the AIR BAG warning lamp does not operate as described, an SIR Diagnostic System Check will be required at an authorized dealership. A scan tool is required to check out the SIR system.
  12.  

2000 Lumina
  1. Remove the key from the ignition switch.
  2.  
  3. Attach the passenger's side air bag yellow 2-way connector which is located behind the instrument panel compartment door and install the CPA pin to verify the connection is secure.
  4.  
  5. Attach the driver's side air bag yellow 2-way connector which is located at the base of the steering column and install the CPA pin to verify the connection is secure.
  6.  
  7. Install the sound insulator trim panels.
  8.  
  9. Install the AIR BAG fuse (may also be identified by a number or as the SIR or SDM fuse) to the instrument panel fuse block. Install the instrument panel fuse block door.
  10.  
  11. Staying well away from both air bags, turn the ignition switch to the ON position. Verify that the AIR BAG warning lamp flashes seven times and then stays off. If the AIR BAG warning lamp does not operate as described, an SIR Diagnostic System Check will be required at an authorized dealership. A scan tool is required to check out the SIR system.
  12.  

 
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