The bumper of our 1998 C1500 was hit just enough to set off the driver's airbag (passenger side didn't deploy because it was turned off). I replaced the airbag out of another 1998 C1500 and checked out the sensor behind the bumper which appears to not be damaged. With everything back together and engine running, the airbag light stays on. Is there anything I can do to cancel out the light besides replacing the airbag computer under the seat? Or does it have to be reset by the dealer?
Beware of misleading info on the web and GM.
I was trying to fix airbag light on my 1999 Suburban. No crash or airbag deployment. Error codes were B1018 and B1015. Removed SDM from under drivers seat and ohmed the loops that the codes says was shorted to ground. Not so! Checked the single sensor on the front bumper area ( only one on the 99, not two described in some manuals and the net) no problem found - replaced it to eliminate it. Cut the sensor apart to see how it worked. It is a totally dump sensor - it is a magnetic reed switch with a 1k ohm resistor across normally open contacts. Mounted around the reed switch is a spring loaded doughnut magnet. If an impact is sufficient to overcome the spring, the doughnut slides far enough to let the reed switch contacts momentarily close - if the car is going fast enough, the SDM would fire the air bag.
To test the sensor: unplug the cable and test the resistance of the two pins - should read 1000 ohms. If you bang the sensor it would go briefly short shorted and return to 1000 ohms. The mounting screws are not electrically connected to sensor. There is no computer talking to this sensor as some info has erroneously stated.
The next lie proved wrong: The SDM 0n a 1999 is not unique to each car. I found an SDM from a junk 99 and replaced mine. Error gone. I suspect that much of the miss-info about the sdm revolves around the fact that big brother wants you not to be able to reset crash info. So, the SDM has a firmware latch that we do not have access to regardless if the original error was legit or not. In my case, there was no permanent short that I could find. My error may have started with a low speed bump/impact with a tree that set the SDM latch without firing the airbag. I do not know if the later year car sensors and SDM are similar. I do know that the SDM is nearly as primitive as the sensor. It has spring loaded switch instead of an modern strain gauge like used in cell phones to detect gravity (orentation) g-force. If you shake the SDM, you can hear the spring loaded switch parts rattle. GM should be ashamed to be asking $300 to $500 for a SDM replacement. The SDM can be reset by people on the web for about $40.