99 Tahoe Air Bag

My air bag warning lite comes on once in a while when I start the truck, goes off after stopping and restarting the engine - might stay off for 2 - 3 weeks then comes on again - I have mechanic check the computor code with his hand held and the code comes up a "1021" which says there is a problem with the air bay electrical circuit- too much resistance - has anyone had similar problem and been able to fix or find the cause

I had a simular problem with my 96 light would stay on sometimes flash for a long time, shop says $1500.00 to fix, few months later the battery went bad, replaced, interesting no problems with the airbag light since.