The C6 Corvette was just removed from winter storage and was about to receive a complete service. The engine roared to life and the instrument panel reflected a systems check. Bulbs were illuminated and would time out, indicating that systems or components were functioning as normal. Moments later, a warning lamp resembling an occupant holding a giant beach ball appeared, indicating a component failure with the SIR/Airbag system. If you have ever encountered or had a visual of an accidental air bag deployment, that lamp illumination will get the adrenaline flowing. Assuming you are not injured, the deployment can leave your face scorched and you may smell funny for the weekend.
Scanning the system revealed a code related to the driver side seat sensor. Clearing the code resulted in an immediate reset of the same code. Cycling the position of the seat to gain access to the seat sensor electrical connector eliminated the fault code, which was an indication of a connection related issue. Loosening the seat from its mounting to gain access to the sensor connector revealed that the connector had dislodged from the seat frame crossbar. The fore and aft movement of the seat re-established continuity within the connector. The ultimate repair was cleaning the connections and securing the connector to the seat crossbar. The addition of a tie strap gave some added insurance that the connector would remain in place and not get dragged across the carpet resulting in another connection related symptom. CAUTION: Prior to disconnecting any SIR sensor, make certain to disconnect the negative battery cable and allow the vehicle manufacturer’s recommended wait time for the energy reserve to discharge, prior to disturbing a connection. If you don’t have access to the recommended wait time, give it several minutes. That may be an overkill but it’s best to be on the safe side.
While conversing about the repair with a dealership technician, we learned of a special coverage by GM for a period of 10 years or 120K miles for this same occurrence. GM Bulletin #15643A references a wiring harness accessory kit to provide additional wiring clearance. The repair procedure prevents the seat sensor connector terminals from pulling loose, as the seat is moved forward or back, while making contact with the carpet. The connector interference is between the vertical adjust crossbar and the carpet. Vehicles included in this campaign involve 2005-2010 Corvettes and 2004-2009 Cadillac XLR. Our vehicle had exceeded the extended coverage period, plus I dislike cutting and splicing a factory wiring harness.
1) Follow the vehicle manufacturer’s recommended procedure and wait time to de-energize
the system prior to service. If not, the results can be devastating physically, mentally and
financially.
2) Do not attach a memory saver tool when servicing the SIR system, as it can keep the system active.
3) Do not apply heat or a hammer in the close proximity of a sensor or module.
4) If you drop a sensor beyond three feet it would be wise to replace it.
5) When testing, follow the vehicle manufacturer’s service procedures and respect the system as if you were handling nitroglycerin.
6) Do not use electrical test equipment other than that recommended by the vehicle manufacturer. The use of test equipment such as battery powered or AC powered voltmeters, ohmmeters or nonpowered probe type testers is not recommended.
7) When making wiring or connection repairs DO NOT use soldering equipment that is battery or electric powered, as they can induce voltage into the circuit, resulting in module or component damage. A butane fueled soldering iron is preferred.
8) Never strike a sensing device in a manner that could result in accidental deployment.
9) When performing an electrical diagnosis on components other than the SIR system, remove the SIR/Airbag fuses when the diagnostic procedure calls for disabling the SIR system.
The passenger airbag indicator or seat belt reminder light/chime may be activated when certain electronic devices such as MP3 players, cell phones or computers are placed in the passenger seat. These electronic devices may interfere with the electric field generated by the Passenger Presence System even though the seat is not occupied. The electronic devices do not have to be turned on to cause these conditions. When troubleshooting, do not lay the scan tool on the passenger seat or touch the seat while the scan tool is in contact with your body to prevent the transfer of electrical noise to the seat sensor mat.
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