Silverado 2008

General Information

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CAUTION
All vehicles are equipped with an air bag system. The system must be disarmed before performing service on, or around, system components, the steering column, instrument panel components, wiring and sensors. Failure to follow the safety precautions and the disarming procedure could result in accidental air bag deployment, possible injury and unnecessary system repairs.

Arming The System



Specific to:

Chevrolet Silverado 1500 2008


NOTE
Do not disconnect the negative battery cable from the battery until a period of at least one minute has passed after performing the following: turning the ignition to OFF, without pausing at ACC, and without applying the brake pedal. These steps are necessary to allow the brake system pressure relief procedure to occur. Failure to follow these steps may result in warning lamps and/or DTC-s being set pertaining to interruption of the pressure relief procedure. Other vehicle systems may also be affected by not allowing a one minute duration for vehicle power down.

To disconnect the negative battery cable, proceed as follows. Turn off all lamps and accessories. Turn the ignition OFF without pausing at ACC, remove the ignition key. Wait at least one minute before disconnecting the negative battery cable from the battery. Reposition the negative battery cable cover from the terminal. Rotate the lock lever counterclockwise in order to disconnect the cable from the battery.


NOTE
After performing the service procedure, to connect the negative battery cable, rotate the lock lever clockwise until an audible click is heard. Position the cover over the terminal.

  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Be sure the ignition switch is in the OFF position.
  4.  
  5. Install the fuses.
  6.  
  7. Connect the negative battery cable.
  8.  
  9. Turn the ignition switch to the ON position.
  10.  
  11. If the system is operating properly the AIR BAG indicator will flash
  12.  
  13. Correct problems as required.
  14.  

Clockspring Centering



Centering Coil

Specific to:

Chevrolet Silverado 1500 2008


NOTE
Do not disconnect the negative battery cable from the battery until a period of at least one minute has passed after performing the following: turning the ignition to OFF, without pausing at ACC, and without applying the brake pedal. These steps are necessary to allow the brake system pressure relief procedure to occur. Failure to follow these steps may result in warning lamps and/or DTC-s being set pertaining to interruption of the pressure relief procedure. Other vehicle systems may also be affected by not allowing a one minute duration for vehicle power down.

To disconnect the negative battery cable, proceed as follows. Turn off all lamps and accessories. Turn the ignition OFF without pausing at ACC, remove the ignition key. Wait at least one minute before disconnecting the negative battery cable from the battery. Reposition the negative battery cable cover from the terminal. Rotate the lock lever counterclockwise in order to disconnect the cable from the battery.


NOTE
After performing the service procedure, to connect the negative battery cable, rotate the lock lever clockwise until an audible click is heard. Position the cover over the terminal.

  1. Before servicing the vehicle, refer to the Precautions Section.
    NOTE
    The new SIR coil assembly will be centered. Improper alignment of the SIR coil assembly may damage the unit, causing an inflatable restraint malfunction.


    NOTE
    If a double wire harness strap is installed onto the wire harness assembly and column, you must reuse the holder for the wire straps during installation. Remove the wire harness strap(s) where necessary.



    Click image to see an enlarged view

    Fig. SIR coil alignment

  2.  
  3. Verify that the front wheels are in the straight ahead position, the tooth block of the steering shaft assembly is in the 12 o-clock position and the ignition switch is in the LOCK position
  4.  
  5. If the front of the SIR coil has a centering window, and the back side includes a spring service lock, hold the coil face up. While depressing the spring service lock, rotate the coil hub clockwise until the coil ribbon stops. Rotate the coil hub slowly, counterclockwise, until the centering window appears yellow and the tooth arrows align. Release the spring service lock between the locking tab. The coil is now centered. Align the coil with the horn tower and slide it onto the steering shaft assembly.

    Click image to see an enlarged view

    Fig. SIR coil alignment locating points

  6.  
  7. If a double wire harness strap is installed onto the wire harness assembly and column, you must route the wires up against the steering column.
  8.  

Replacing Coil

Specific to:

Chevrolet Silverado 1500 2008


NOTE
Do not disconnect the negative battery cable from the battery until a period of at least one minute has passed after performing the following: turning the ignition to OFF, without pausing at ACC, and without applying the brake pedal. These steps are necessary to allow the brake system pressure relief procedure to occur. Failure to follow these steps may result in warning lamps and/or DTC-s being set pertaining to interruption of the pressure relief procedure. Other vehicle systems may also be affected by not allowing a one minute duration for vehicle power down.

To disconnect the negative battery cable, proceed as follows. Turn off all lamps and accessories. Turn the ignition OFF without pausing at ACC, remove the ignition key. Wait at least one minute before disconnecting the negative battery cable from the battery. Reposition the negative battery cable cover from the terminal. Rotate the lock lever counterclockwise in order to disconnect the cable from the battery.


NOTE
After performing the service procedure, to connect the negative battery cable, rotate the lock lever clockwise until an audible click is heard. Position the cover over the terminal.

  1. Before servicing the vehicle, refer to the Precautions Section.
    NOTE
    When performing service on or near the SRS components, or SRS wiring the SRS must be disabled. Failure to observe the correct procedure could cause deployment of the SRS components. Serious injury can occur.

  2.  
  3. Position the steering wheel so the front wheels are in the straight ahead position.
  4.  
  5. Be sure the ignition switch is in the OFF position.
  6.  
  7. Disconnect the negative battery cable.
    NOTE
    The SDM may have more than one fused power input. To ensure that there is no unwanted SRS deployment, personal injury, or unnecessary SRS system repairs, remove all fuses supplying power to the SDM. With all SDM fuses removed and the ignition switch in the ON position, the AIR BAG warning indicator will illuminate. This is normal and does not indicate a SRS system malfunction.

  8.  
  9. Locate and remove the fuses supplying power to the SDM.
  10.  
  11. Wait one minute before working on the vehicle.
    NOTE
    Check that the front wheels are in the straight ahead position. Secure the steering wheel using the steering column anti-rotation pin, steering column lock, or a strap to prevent rotation. Locking the steering column will prevent damage and a possible malfunction of the SRS system. The steering wheel must be secured when disconnecting the intermediate shaft and the steering gear. After disconnecting these components do not rotate the steering wheel or move the front wheels. Failure to follow this procedure may cause the SRS coil assembly to become uncentered and cause possible damage to the SRS coil.



    Click image to see an enlarged view

    Fig. Steering wheel lock pin tool and location access point

  12.  
  13. Lock the steering column through the access hole in the lower steering column trim cover using tool J-42640 or equivalent.
  14.  
  15. Remove the driver-s side air bag module.

    Click image to see an enlarged view

    Fig. Driver-s side air bag module and related components



    Click image to see an enlarged view

    Fig. Steering wheel and related components

  16.  
  17. Remove the steering wheel retaining nut. Using the proper puller, carefully remove the steering wheel.
  18.  
  19. Remove the screws from the lower trim cover. Remove the lower trim cover.
  20.  
  21. Remove the screws from the upper trim cover. Remove the upper trim cover.

    Click image to see an enlarged view

    Fig. Upper and lower steering column shrouds and related components

  22.  
  23. Disconnect electrical connectors, as required.
  24.  
  25. Remove the retaining ring. Discard the ring. Remove the SIR coil from the steering shaft.

    Click image to see an enlarged view

    Fig. SIR coil and related components



    Click image to see an enlarged view

    Fig. Installing the SIR coil

  26.  

To install:


NOTE
Be sure to use new fasteners, as required.


NOTE
The new SIR coil assembly will be centered. Improper alignment of the SIR coil assembly may damage the unit, causing an inflatable restraint malfunction.

  1. Verify that the wheels are in the straight ahead position and that tool J42640 is installed or the ignition switch is in the LOCK position.
    NOTE
    Do not remove the centering tab from the new SIR coil until the installation is complete. If the SIR coil does not come with a centering tab, you must center the coil.


    NOTE
    If reusing the existing coil it must be centered.

  2.  
  3. Center the SIR coil, as required.
  4.  
  5. Align the SIR coil assembly with the horn tower on the turn signal cancel cam assembly.
  6.  
  7. Slide the SIR coil onto the steering shaft assembly.
  8.  
  9. Firmly seat the retaining ring into the groove on the steering shaft assembly.
    NOTE
    If installing a new SIR coil, remove and discard the centering tab, if equipped.

  10.  
  11. Install the upper trim cover. Tighten the retaining screws to 13 inch lbs.
  12.  
  13. Install the lower trim cover.
  14.  
  15. Verify the upper and lower retaining tabs engage with each other. Tighten the screws to 13 inch lbs.
  16.  
  17. Continue the installation in the reverse order of the removal procedure.
  18.  
  19. Be sure the ignition switch is in the OFF position.
  20.  
  21. Install the fuses.
  22.  
  23. Connect the negative battery cable.
  24.  
  25. Turn the ignition switch to the ON position.
  26.  
  27. If the system is operating properly the AIR BAG indicator will flash
  28.  
  29. Correct problems as required.
  30.  
  31. Be sure the ignition switch is in the OFF position.
  32.  
  33. Install the fuses.
  34.  
  35. Connect the negative battery cable.
  36.  
  37. Turn the ignition switch to the ON position.
  38.  
  39. If the system is operating properly the AIR BAG indicator will flash
  40.  
  41. Correct problems as required.
  42.  

Description And Operation



Specific to:

Chevrolet Silverado 1500 2008

The Supplemental Inflatable Restraint (SIR) System supplements the protection offered by the occupant-s seat belt. The SIR system may contain several inflator modules located throughout the vehicle, i.e. steering wheel module and instrumental panel (I/P) module. In addition to inflator modules, the vehicle contains an inflatable restraint Passenger Presence System (PPS) that measure the weight of an occupant sitting in the front passenger seat. The PPS uses the weight of the occupant to determine if the I/P inflator module will be enabled or disabled. Each inflator module has a deployment loop that is controlled by the sensing and diagnostic module (SDM) mounted inside the vehicle. The SDM determines the severity of a collision with the assistance of various sensor inputs. When the SDM detects a collision of sufficient force it will process the information provided by the sensors to further support air bag deployment. The SDM performs continuous diagnostic monitoring of the SIR system electrical components. Upon detection of a circuit malfunction, the SDM will set a DTC and inform the driver by requesting the instrument panel cluster (PIC) to turn the AIR BAG indictor ON. The steering column and knee bolsters are designed to absorb energy and compress during frontal collisions in order to limit leg movement and decrease the chance of injury to the driver and passenger.

Click image to see an enlarged view

Fig. SRS and related components

Service Precautions



Specific to:

Chevrolet Silverado 1500 2008

Disconnect and isolate the battery negative cable before beginning any airbag system component diagnosis, testing, removal, or installation procedures. Allow system capacitor to discharge for two minutes before beginning any component service. This will disable the airbag system. Failure to disable the airbag system may result in accidental airbag deployment, personal injury, or death.

Do not place an intact undeployed airbag face down on a solid surface. The airbag will propel into the air if accidentally deployed and may result in personal injury or death.

When carrying or handling an undeployed airbag, the trim side (face) of the airbag should be pointing towards the body to minimize possibility of injury if accidental deployment occurs. Failure to do this may result in personal injury or death.

Replace airbag system components with OEM replacement parts. Substitute parts may appear interchangeable, but internal differences may result in inferior occupant protection. Failure to do so may result in occupant personal injury or death.

Wear safety glasses, rubber gloves, and long sleeved clothing when cleaning powder residue from vehicle after an airbag deployment. Powder residue emitted from a deployed airbag can cause skin irritation. Flush affected area with cool water if irritation is experienced. If nasal or throat irritation is experienced, exit the vehicle for fresh air until the irritation ceases. If irritation continues, see a physician.

Do not use a replacement airbag that is not in the original packaging. This may result in improper deployment, personal injury, or death.

The factory installed fasteners, screws and bolts used to fasten airbag components have a special coating and are specifically designed for the airbag system. Do not use substitute fasteners. Use only original equipment fasteners listed in the parts catalog when fastener replacement is required.

During, and following, any child restraint anchor service, due to impact event or vehicle repair, carefully inspect all mounting hardware, tether straps, and anchors for proper installation, operation, or damage. If a child restraint anchor is found damaged in any way, the anchor must be replaced. Failure to do this may result in personal injury or death.

Deployed and non-deployed airbags may or may not have live pyrotechnic material within the airbag inflator.

Do not dispose of driver/passenger/curtain airbags or seat belt tensioners unless you are sure of complete deployment. Refer to the Hazardous Substance Control System for proper disposal.

Dispose of deployed airbags and tensioners consistent with state, provincial, local, and federal regulations.

After any airbag component testing or service, do not connect the battery negative cable. Personal injury or death may result if the system test is not performed first.

If the vehicle is equipped with the Occupant Classification System (OCS), do not connect the battery negative cable before performing the OCS Verification Test using the scan tool and the appropriate diagnostic information. Personal injury or death may result if the system test is not performed properly.

Never replace both the Occupant Restraint Controller (ORC) and the Occupant Classification Module (OCM) at the same time. If both require replacement, replace one, then perform the Airbag System test before replacing the other.

Both the ORC and the OCM store Occupant Classification System (OCS) calibration data, which they transfer to one another when one of them is replaced. If both are replaced at the same time, an irreversible fault will be set in both modules and the OCS may malfunction and cause personal injury or death.

If equipped with OCS, the Seat Weight Sensor is a sensitive, calibrated unit and must be handled carefully. Do not drop or handle roughly. If dropped or damaged, replace with another sensor. Failure to do so may result in occupant injury or death.

If equipped with OCS, the front passenger seat must be handled carefully as well. When removing the seat, be careful when setting on floor not to drop. If dropped, the sensor may be inoperative, could result in occupant injury, or possibly death.

If equipped with OCS, when the passenger front seat is on the floor, no one should sit in the front passenger seat. This uneven force may damage the sensing ability of the seat weight sensors. If sat on and damaged, the sensor may be inoperative, could result in occupant injury, or possibly death.

Disarming The System



Specific to:

Chevrolet Silverado 1500 2008


NOTE
Do not disconnect the negative battery cable from the battery until a period of at least one minute has passed after performing the following: turning the ignition to OFF, without pausing at ACC, and without applying the brake pedal. These steps are necessary to allow the brake system pressure relief procedure to occur. Failure to follow these steps may result in warning lamps and/or DTC-s being set pertaining to interruption of the pressure relief procedure. Other vehicle systems may also be affected by not allowing a one minute duration for vehicle power down.

To disconnect the negative battery cable, proceed as follows. Turn off all lamps and accessories. Turn the ignition OFF without pausing at ACC, remove the ignition key. Wait at least one minute before disconnecting the negative battery cable from the battery. Reposition the negative battery cable cover from the terminal. Rotate the lock lever counterclockwise in order to disconnect the cable from the battery.


NOTE
After performing the service procedure, to connect the negative battery cable, rotate the lock lever clockwise until an audible click is heard. Position the cover over the terminal.

  1. Before servicing the vehicle, refer to the Precautions Section.
    NOTE
    When performing service on or near the SRS components, or SRS wiring the SRS must be disabled. Failure to observe the correct procedure could cause deployment of the SRS components. Serious injury can occur.

  2.  
  3. Position the steering wheel so the front wheels are in the straight ahead position.
  4.  
  5. Be sure the ignition switch is in the OFF position.
  6.  
  7. Disconnect the negative battery cable.
    NOTE
    The SDM may have more than one fused power input. To ensure that there is no unwanted SRS deployment, personal injury, or unnecessary SRS system repairs, remove all fuses supplying power to the SDM. With all SDM fuses removed and the ignition switch in the ON position, the AIR BAG warning indicator will illuminate. This is normal and does not indicate a SRS system malfunction.

  8.  
  9. Locate and remove the fuses supplying power to the SDM.
  10.  
  11. Wait one minute before working on the vehicle.
  12.  

 
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