from http://www.nissanforums.com/966228-post7.html Here's the process to reset the air bag light (copied from somewhere else on the forum)... I tried it and it works.
If you have the airbag light, it will show steady for a few seconds (the manual says 7 secs) after you turn the key from off to on (but not start) and then start to flash. Here is how to reset it:
1. Turn the key from off to on.
2. Watch the airbag light closely. It will stay on for a few secs. and then as soon as it blinks off (the start of the flashing), turn the key off instantly.
3. Count to 5 (1 Mississippi, 2 Mississippi . . . .)
4. Repeat steps 1-3 two more times until you have done the cycle three times.
5. Now turn the key on and watch the light. It will start blinking in a different, slower manner. This is diagnostic mode. You can watch this for a little while, no hurry.
6. Now turn the key off again, Count to 5 like in step 3 again, and turn back on. If the procedure worked, the airbag light will not be flashing.
If it does not work the first time, just repeat the steps again.
rear window defroster light keeps flashing
The overdrive off light flashing - indicates a malfunction has been detected
overdrive light keeps flashing
if it keeps flashing on and off
If the hold light keeps flashing on a Kia Sportage a sensor may be malfunctioning in the light. The flashing light could also indicate that a speed sensor is going bad.
lookup on youtube and follow altima airbag reset it's the same
if its a used vehicle it could be because it was in a previous accident and the air bags have been deployed
might be a misfire in a cylinder...
It is important to pay attention to the warning lights in a car. When an airbag light comes on, in any manner, it means there is an issue with the airbag.
my dimmer light in the dash keeps flashing even when the lights are not turned on
TV won't turn on and the Stand By Light keeps flashing.
To reset your airbag light, in a Nissan Altima, you should turn the car on. From there, as soon as the airbag light stops flashing, turn the car off instantly. Repeat this three times to reset the airbag light.