I've heard of two scenarios to turn off the service light. I assume that we're talking about the same one, since my dash only has a light that comes on that service but no "service engine soon" light.
First one...
1) Press and hold the odometer reset button.
2) Turn ignition switch to the "run" position
3) After SRL light flashes, release the odometer reset button.
4) Turn off ignition switch then start to confirm that the reset is accepted.

Second one which is the one that worked for me.
1) Make sure that trip counter is on T-1
2) Turn ignition switch to position 1.
3) Press and hold the trip meter reset button until it shows "zero".
4) While still holding the button in, turn ignition to position 2.
5) When the original trip mileage returns, release the reset button and turn off the ignition.

Hope that this helps, our two vehicles are different years, so, who knows what changes in a few years?