The coiled circuit assembly in the steering wheel provides contact for the air bag and the horn switches.  Picture  The slightest fault in the coiled circuit assembly - corrosion of any kind - will cause the SRS light to come on.  You can have the light reset at the dealer, but it will probably just come on again in a short while.  The fact is, the air bag will probably work in the event of a crash, SRS light or no.  After all, the horn doesn't fail because of a little bit of corrosion, does it?  No.  The SRS light function is sensitive, but the air bag itself will almost certainly work.  Nonetheless, you always wonder, don't you?  You want that darn air bag to work if you need it.  Plus, that light can get really irritating.  Well, the good news is that it's really easy to replace the coiled circuit assembly.  The bad news is that it's ridiculously expensive: $125  or so.  Most of us are scared to death of air bags.  I sure was.  However, a dealer mechanic assured me that removing the bag assembly is safe and easy.  Mucking around with the control unit is the dicey part.  I removed and reinstalled my air bag without any problems, and it seems routine to me now.

I disconnected the battery negative cable and then waited half an hour. I doubt that the half hour wait is really necessary, but it's standard procedure with airbag work, so I did it.  I would absolutely disconnect the battery before removing the air bag.  And yeah, I'll always wait the half hour ... call it superstition if you want.  Be sure that you know your radio code before disconnecting the battery.

Working from below the steering wheel, remove the four screws that secure the bottom steering wheel plastic trim box to the top trim box.  Picture  Pull the lower trim piece out.

There are two screws recessed into the back of the steering wheel, one on each side, that hold the air bag assembly in place.  Put the key in the ignition and turn the key to the run position so the wheel can be turned.  Turn the wheel until the spoke is perpendicular.  Working from below the dash, fully loosen the T-30 screw in the back side of the steering wheel.  The screws are captive, so they won't actually come out.  Now turn the wheel 180 degrees so you can get to the other screw; loosen it.  Grasp the center section of the steering wheel (that's actually the air bag assembly) and pull it out.  Picture 

Now pry the connector loose - it's a simple press-in fit.

Put the airbag assembly somewhere where it won't be disturbed.  It's not dynamite, but it does contain an explosive charge, so put it somewhere where it won't be disturbed.

Pull the horn connector out of the rubber retainer, then separate the connectors by pushing on the release tabs with a sharp tool or very small screwdriver inserted into the access hole Picture

Mark the position of the steering wheel on the steering column, then remove the steering wheel nut - 22 mm socket (7/8" will also work).

Pull the steering wheel off; pulling the horn and airbag connectors through the hole at the top of the wheel steering hub.

Cut the cable tie that secures the airbag and horn input connectors to the steering column, then disconnect the connectors.  Picture

Remove the two T-25 screws that secure the coiled circuit assembly.  You'll need to pull the upper plastic trim piece out and up a bit to gain access to the upper screw.  Picture

Pull the coiled circuit assembly off the steering column.

Install the new coiled circuit assembly and tighten the screws just snug. 

Connect the airbag and horn input connectors and secure them to the steering column with a cable tie.

Thread the airbag and horn "input" connectors through the access hole in the steering wheel, then align the steering wheel and steering shaft reference marks that you made earlier, and slip the wheel onto the steering column shaft.   There is a plastic peg protrusion on the coiled circuit assembly that mates with the steering wheel; I should have noted how this mates, but I didn't.  It may be necessary to rotate the coiled circuit assembly a bit to get proper alignment.

 Install the steering wheel retaining washer and nut and tighten securely.

Connect the horn connector at the steering wheel, then push it into the rubber retaining fingers.

Snap the airbag connector into the airbag.  I could not discern any polarity to the connection.

Put the airbag in place, align the screws to the holes and tighten the screws securely.

Make sure the ignition key is turned off (to minimize electrical load), then reconnect the negative battery cable and tighten it securely.