GM Bonneville/Eighty Eight/LeSabre 1986-1999

General Description

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See Figures 1 and 2

If your vehicle is a pre-1992 Oldsmobile Delta 88/Eighty Eight equipped with an air bag, turn to the following section on the Oldsmobile Inflatable Restraint (IR) Air Bag System for information.

The air bag system used on most vehicles covered by this information is referred to as the Supplemental Inflatable Restraint (SIR) system. The air bag is designed to deploy when the vehicle is involved in a front end collision of sufficient force, up to 30 degrees off center line of the vehicle. The steering column still continues to be collapsible, the same as on vehicles without an air bag.

1992-99 Bonneville, Eighty Eight, and LeSabre models use GM's Generation 1 Corporate (GEN 1) Supplemental Inflatable Restraint system, also simply referred to as the SIR system. This system has an energy reserve, which can store a large enough electrical charge to deploy the air bag for 10 minutes after the battery has been disconnected or damaged. This system must be disabled if any service is to be performed on the SIR system or steering wheel assembly.

Throughout this repair guide, you may find air bag systems referred to as Supplemental Inflatable Restraint (SIR), Inflatable Restraint (IR) system, or even Supplemental Restraint System (SRS). In this book, SIR is the Generation 1 system and IR is the Oldsmobile developed Inflatable Restraint system.

Many later model vehicles may be equipped with a driver and a passenger side air bag. When a frontal crash occurs of sufficient force, up to 30° off the centerline of the vehicle, a bag is deployed from both the center of the steering wheel and from above the instrument panel compartment on the passenger's side.



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Fig. Fig. 1: SIR system "deployment window"

The system has an energy reserve, which can store a large enough electrical charge to deploy the air bag(s) for up to ten minutes after the battery has been disconnected or damaged. The system MUST be disabled before any service is performed on or around SIR components or SIR wiring.

The GEN 1 system requires the replacement of all sensors and inflator module after a deployment. This system has self-diagnostic ability. Although some diagnostic codes can be obtained by counting flashes of the INFLATABLE RESTRAINT lamp, other codes can only be obtained or cleared by using a scan tool.



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Fig. Fig. 2: The SIR system components, when used with a seat belt, can provide additional protection during an accident

SYSTEM OPERATION



Except Vehicles With Dual Air Bags

The SIR system contains a deployment loop and a Diagnostic Energy Reserve Module (DERM). The function of the deployment loop is to supply current through the inflator module in the steering wheel, which will cause air bag deployment during a severe accident. The DERM supplies the necessary power, even if the battery has been damaged.

The deployment loop is made up of the arming sensors, coil assembly, inflator module and the discriminating sensors. The inflator module is only supplied sufficient current to deploy the air bag, when the arming sensors and at least one of the discriminating sensors close simultaneously. The function of the DERM is to supply the deployment loop a 36 Volt Loop Reserve (36VLR) to assure air bag deployment for seconds after ignition voltage is lost during an accident.

The DERM in conjunction with the resistors make it possible to detect circuit and component faults within the deployment loop. If the voltages monitored by the DERM fall outside expected limits, the DERM will indicate a fault code through the storage of a malfunction code and turning ON the INFLATABLE RESTRAINT lamp.

Vehicles With Dual Air Bags

The DERM along with both the driver and passenger deployment loops are the main portion of the SIR system. Each deployment loop's main function is to supply current through its inflator module, allowing air bag deployment in the event of a frontal crash severe enough to warrant deployment.

A dual pole arming sensor, coil assembly (driver's side only), inflator module and 2 discriminating sensors make up each deployment loop. The dual pole arming sensor switches power to the inflator module on each deployment loop's high side. Either discriminating sensor can supply ground to the inflator modules on the loops' low side. The inflator modules are supplied with sufficient current to deploy only when the dual pole arming sensor and at least 1 discriminating sensor close simultaneously.

SYSTEM COMPONENTS



See Figure 3

Diagnostic Energy Reserve Module (DERM)

The DERM is also called the Sensing and Diagnostic Module (SDM) on later vehicles; however it serves the same purpose.

The DERM is designed to perform 5 main functions. It maintains an energy reserve of 36 volts for several seconds. The DERM performs diagnostic monitoring of the SIR system and records malfunction codes, which can be obtained from a hand scan tool or the INFLATABLE RESTRAINT lamp. It warns the driver of a malfunction by controlling the INFLATABLE RESTRAINT lamp and keeps a record of the SIR system during a vehicle accident. Air bag deployment can still take place without the DERM connected, if adequate voltage is present at the arming sensor or dual pole sensor.

The DERM is connected to the system with a 24-way connector. This harness has a shorting bar across certain terminals in the contact areas. The shorting bar connects the INFLATABLE RESTRAINT lamp input to ground when the DERM is disconnected causing the lamp to light when the ignition switch is ON .

The DERM does not need to be replaced after each air bag deployment. After 4 deployments the DERM will register a Code 52. The Code 52 informs that the accident memory is full and the DERM must be replaced.



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Fig. Fig. 3: Typical SIR component locations - 1996 vehicle shown, others similar

Inflatable Restraint Indicator

The INFLATABLE RESTRAINT or AIR BAG indicator lamp is used to verify the DERM operation by flashing 7-9 times when the ignition is first turned ON . It is also used to warn the driver of a SIR malfunction. For certain tests it can provide diagnostic information by flashing the fault code when the fault code diagnostic mode is enabled.

Discriminating Sensor

There can be 2, 3 or 4 discriminating sensors. The forward, left or right sensors are located in the engine compartment. The passenger sensor, if equipped, is located behind the right side of the instrument panel or the center of the console. These sensors are calibrated to close with velocity changes which are severe enough to warrant air bag deployment.

The sensors consist of a sensing element, a normally open switch and a diagnostic resistor. The diagnostic resistor is wired in parallel with the switch within each sensor. They provide a ground for current to pass during normal non-deployment operation. The DERM measures this current to determine component faults.

When the arming sensor is located in the same housing as the passenger compartment discriminating sensor, the assembly is referred known as a dual sensor.

Arming Sensor

This sensor is found on vehicles with a single air bag.

All sensors are specifically calibrated to each series vehicle and keyed to the mounting brackets. Great care must be taken to mount the correct sensors on the vehicle being serviced. The sensors, mounting brackets and wiring harness must never be modified from original design.

The arming sensor is a protective switch in the power feed side of the deployment loop. It is calibrated to close at low level velocity changes. This insures that the inflator module is connected to the 36VLR output of the DERM or ignition 1 voltage.

The sensor consists of a sensing element, normally open switch a diagnostic resistor and 2 steering diodes. The resistor is connected in parallel with the switch and allows a small amount of current to flow through the deployment loop during normal non-deployment operation. The DERM monitors this voltage to determine component faults.

The arming sensor is located in the same housing as the passenger compartment discriminating sensor. The assembly is referred to as the dual sensor and is located behind the right side of the instrument panel.

Passenger Compartment Discriminating Sensor

This sensor can either be part of the dual sensor or can be a separate sensor altogether.

Dual Sensor

On single air bag vehicles so equipped, the dual sensor is a sensor that combines the arming sensor and the passenger compartment discriminating sensor into the same unit.

Dual Pole Arming Sensor

This sensor is on vehicles with dual air bags. It is located behind the left side of the instrument panel above the steering column.

The dual pole arming sensor is a dual pole switch located in the driver/passenger deployment loop's power feed side (high side). It consists of a sensing element that closes the normally open dual switch contacts when the vehicle velocity changes at a rate indicating potential need for deployment.

SIR Coil Assembly

See Figure 4

The coil assembly consists of 2 current carrying coils. They are attached to the steering column and allow rotation of the steering wheel, while maintaining continuous contact of the deployment loop through the inflator module.



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Fig. Fig. 4: The SIR coil is mounted on the steering column

There is a shorting bar on the lower steering column connector, which connects the SIR coil to the SIR harness. The shorting bar shorts the circuit when the connector is disconnected. The circuit to the module is shorted in this way to help prevent unwanted deployment of the air bag, while performing service.

Inflator Module
SINGLE AIR BAG

See Figures 5 and 6

The inflator module is located in the steering wheel hub under the vinyl trim. It includes the air bag, inflator and initiator. When the vehicle is in an accident, current is passed through the deployment loop. This current passing through the deployment loop ignites the squib in the inflator module. The gas produced rapidly inflates the air bag.

There is a shorting bar on the lower steering column connector, which connects the SIR coil to the SIR harness. The shorting bar shorts the circuit when the connector is disconnected. The circuit to the module is shorted in this way to help prevent unwanted deployment of the air bag, while performing service.



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Fig. Fig. 5: Exploded view of the driver's side SIR inflator module - Oldsmobile and Buick shown



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Fig. Fig. 6: The driver's side SIR inflator module is mounted to the steering wheel - Pontiac shown

DUAL AIR BAGS

See Figures 7, 8 and 9

The 1993 Bonneville SSE and SSEi, and all 1994-99 vehicles are equipped with a driver/passenger SIR system which has 2 inflator modules. The driver inflator module is located on the steering wheel, while the passenger inflator module is mounted in the instrument panel above the instrument panel compartment. Each module includes the air bag, inflator and initiator. When the vehicle is in a frontal crash of sufficient force to close the dual pole arming sensor and at least one discriminating sensor simultaneously, current flows through both deployment loops. The current passing through the initiators ignites the material in the inflator modules and the air bags are inflated.



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Fig. Fig. 7: Location of the passenger SIR inflator module - Oldsmobile shown



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Fig. Fig. 8: Exploded view of the passenger SIR inflator module - Buick shown



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Fig. Fig. 9: Passenger SIR inflator module mounting - Pontiac shown

There is a shorting bar on the driver inflator module side of the upper steering column connector, which connects the SIR coil to the driver inflator module. The shorting bar shorts the driver inflator module circuit when the SIR coil connector is disconnected. The circuit to the module is shorted in this way to help prevent unwanted deployment of the air bag while performing service.

There is also a shorting bar on the passenger inflator module connector, which connects the SIR wiring harness to the passenger inflator module. The shorting bar shorts the passenger inflator module circuit whenever this connector is disconnected. The circuit to the module is shorted in this way to help prevent unwanted deployment of the air bag while performing service.

Resistor Module

This component is found on vehicles with a single air bag. The resistor module is in the SIR harness between the inflator module and DERM. This allows the DERM to monitor the deployment loop for faults and also allows the DERM to detect if the air bag has been deployed.

The resistors in the resistor module are balanced with the resistors in the arming and discriminating sensors to allow the DERM to monitor voltage drops across the circuits. These resistors also help reduce the possibility of unwanted deployment in the case of wiring harness damage.

Knee Bolster

The knee bolster is used to absorb energy and control the driver's forward movement during an accident by limiting leg movement.

Fuse Panel

Vehicles with dual air bags have a specific fuse panel located in the lower instrument panel trim pad. It is hinged to swing out for easy access.

When closing the swing out fuse panel, the lever that was pulled to open it must also be pulled when closing it. Failure to do so may damage the latch mechanism and prevent the fuse panel from staying closed.

Wiring Harness and Connectors

The wiring harness and connectors for the SIR system are of special design. Any wiring repairs should be done using tool kit J-38125, or equivalent. Always use the crimp and seal splice sleeves contained in this wiring repair kit. If damage is done to a component pigtail the component must be replaced.

SERVICE PRECAUTIONS



See Figures 10 and 11


CAUTION
To avoid personal injury when servicing the SIR system or components in the immediate area, do not use electrical test equipment such as battery or AC powered voltmeter, ohmmeter, etc. or any type of tester other than specified. Do not use a non-powered probe tester. Instructions must be followed in detail to avoid deployment.

  1. When performing service around the SIR system components or wiring, the SIR system MUST be disabled. Failure to do so could result in possible air bag deployment, personal injury or unneeded SIR system repairs.
  2.  
  3. When carrying a live inflator module, make sure that the bag and trim cover are pointed away from you. Never carry the inflator module by the wires or connector on the underside of the module. In case of accidental deployment, the bag will then deploy with minimal chance of injury.
  4.  
  5. When placing a live inflator module on a bench or other surface, always face the bag and trim cover up, away from the surface.
  6.  



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Fig. Fig. 10: Proper handling of a live inflator module

  1. Never disconnect any electrical connection with the ignition switch ON unless instructed to do so in a test.
  2.  
  3. Always wear a grounded wrist static strap when servicing any control module or component labeled with a Electrostatic Discharge (ESD) sensitive device symbol.
  4.  



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Fig. Fig. 11: This symbol indicates that a component is sensitive to Electrostatic Discharge (ESD)

  1. Avoid touching module connector pins.
  2.  
  3. Leave new components and modules in the shipping package until ready to install them.
  4.  
  5. Always touch a vehicle ground after sliding across a vehicle seat or walking across vinyl or carpeted floors to avoid static charge damage.
  6.  
  7. The DERM can maintain sufficient voltage to cause a deployment for up to 10 minute, even if the battery is disconnected.
  8.  
  9. Sensor mounting and wiring must never be modified.
  10.  
  11. Never strike or jar a sensor, or deployment could occur.
  12.  
  13. Never power up the SIR system when any sensor is not rigidly attached to the vehicle.
  14.  
  15. The inflator module is to be stored and shipped under DOT E-8236 flammable solid regulations.
  16.  
  17. The inflator module must be deployed before it is discarded.
  18.  
  19. After deployment the air bag surface may contain sodium hydroxide dust. Always wear gloves and safety glasses when handling the assembly. Wash hands with mild soap and water afterwards.
  20.  
  21. A Code 51 requires, at minimum, replacement of the arming sensor, passenger compartment discriminating sensor, forward discriminating sensor and the inflator module.
  22.  
  23. Any visible damage to sensors requires component replacement.
  24.  
  25. Wire and connector repair must be performed using kit J-38125-A, or equivalent. Use special crimping tools, a heat torch and seals.
  26.  
  27. Absolutely no wire connector, or terminal repair is to be attempted on the arming sensor, passenger compartment discriminating sensor, forward discriminating sensor, inflator module or SIR coil assembly
  28.  
  29. Never use a battery or AC powered test light or tester on the SIR system or deployment could occur.
  30.  
  31. Never use an ohmmeter on the SIR system, unless instructed to do so, or deployment could occur.
  32.  
  33. Never bake dry paint on vehicle or allow to exceed temperatures over 300°F, without disabling the SIR system and removing the inflator module.
  34.  
  35. Sensors are not interchangeable between models or years.
  36.  
  37. Never allow welding cables to lay on, near or across any vehicle electrical wiring.
  38.  
  39. Avoid extension cords for power tools or droplights to lay on, near or across any vehicle electrical wiring.
  40.  

DISARMING THE SIR SYSTEM



See Figures 12, 13, 13, 14, 15 and 16

Proper and safe operation requires the sensor, brackets and wiring to be installed in the exact locations of design. All components service must be exactly aligned and tighten to exact torque specification. It is not advisable to service the air bag system. The information provided is to help you understand the system and disarm the system if other non-air bag system service are to be performed.

Before beginning the disarming procedure, read all service precautions.

  1. Turn the steering wheel so that the vehicle's wheels are pointing straight ahead.
    1. Turn the ignition switch to the LOCK position, remove the key, then disconnect the negative battery cable.
    2.  

  2.  
  3. Wrap the end of the battery cable with tape to avoid possible terminal contact.
  4.  
  5. Remove the AIRBAG fuse (fuse #7 for 1992-93 vehicles, or #1C for 1994-99 vehicles) from the fuse block.
  6.  

With the AIRBAG fuse removed and the ignition in the

RUN position, the AIR BAG warning lamp illuminates. This is a normal operation and does not indicate a system malfunction.

  1. Remove the left side sound insulator/steering column filler panel and courtesy lamp, as needed.
  2.  
  3. Remove the Connector Positive Assurance (CPA) lockpin on the yellow 2-way connector at the base of the steering column.
  4.  
  5. Unplug the yellow 2-way SIR connector, located near the base of the steering column.
  6.  



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Fig. Fig. 12: Location of the driver's side SIR 2-way connector - 1987-93 vehicles

  1. If equipped with a passenger side air bag, remove the right side instrument panel sound insulator to access the connector. Remove the CPA lockpin, then unplug the yellow 2-way passenger inflator module connector. The connector is located at the base of the right side instrument panel, clipped to the knee bolster (tie bar and steering column filler).
  2.  



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Fig. Fig. 13: Location of the passenger's side SIR connector - 1993 vehicle shown



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Fig. Fig. 14: Location of the passenger's side 2-way connector - 1994-99 Oldsmobile shown



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Fig. Fig. 15: Passenger's side SIR connector location - 1994-99 Buick shown



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Fig. Fig. 16: Location of the 1994-99 Pontiac passenger's side SIR connector

  1. If necessary, connect the negative battery cable. The system can now be safely serviced.
  2.  

ENABLING THE SYSTEM



Before beginning the enabling procedure, read all service precautions.

  1. Make sure the ignition switch is in the LOCK position, then remove the key from the ignition.
  2.  
  3. If not already done, disconnect the negative battery cable and tape the end of cable to avoid possible terminal contact.
  4.  
  5. If equipped with a passenger's side air bag, attach the yellow 2-way connector and the CA to the inflatable restraint instrument panel module pigtail. Install the right side instrument panel sound insulator.
  6.  
  7. Reconnect the SIR 2-way yellow connector at the base of the steering column. Reinstall the CPA lockpin on the yellow connector.
  8.  
  9. Install the left side sound insulator/steering column filler panel and lamp, if removed.
  10.  
  11. Install the SIR fuse in the fuse panel.
  12.  
  13. Connect the battery cable.
  14.  
  15. Staying well away from both air bags, turn the ignition switch to the RUN position and check that the INFLATABLE RESTRAINT/AIR BAG lamp flashes 7-9 times and then goes out.
  16.  

 
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