see this and fix it.
AIR BAG SENSOR REPLACEMENT
Several very important points must be kept in mind about replacing
crash sensors. One is to make sure the replacement is the correct one
for the application. Crash sensors are calibrated for specific vehicle
applications, so compare OEM part numbers to make sure your parts
supplier has given you the correct replacement crash sensor.
The mounting of the crash sensor is also critical. A replacement
sensor must be installed in exactly the same location and the same
position as the original. The sensor must also be firmly attached so it
won't break loose in a future collision. Altering the mounting location
or position of a sensor may cause it to trigger the air bag accidentally
or not at all.
CRASH SENSOR CHECKS
The air bag control module self-checks the crash sensors every time
the engine is started, so unless the air bag warning light is on the
sensors are assumed to be okay. If a fault is detected, the air bag
warning light will come on and usually deactivate the air bag system.
Using a scan tool, you can pull the trouble code from the system and
refer to the appropriate diagnostic chart in a service manual to
troubleshoot the problem. Air bag service information can also be found
on the vehicle manufacturer's website (Click Here
for a list of websites and access fees). Loss of circuit continuity
anywhere in the air bag system, or loss of power to the air bag module
are common causes of trouble codes.
Because crash sensors are sealed units, you cannot always determine
their true condition by outward appearances. Any sensor that is
obviously sustained physical damage as a result of a collision or other
damage should be replaced. But what about ones that look okay? Most
electromechanical crash sensors are designed to be electrically open in
their rest condition. So one quick check you can perform is to check for
continuity with an ohmmeter. If the sensor contacts are closed, it has
not reset and should be replaced.