You could perform this test to see if the intrument cluster is driving the CEL properly.
As the cluster goes through its presets, the CEL will come on for 4 seconds, go off for 2 seconds, then back on for 2 seconds, then off again. If the CEL remains on all the time the instrument cluster may be at fault.
Instrument Cluster Actuator Test
(1) Begin the test with the ignition switch in the Off position.
(2) Depress the trip odometer reset button.
(3) While holding the trip odometer reset button depressed, turn the ignition switch to the On (RUN) position, but do not start the engine.
(4) Release the trip odometer reset button.
(5) The gauges should cycle through their ranges, stopping at intermediate readings, going up and going down, at two second intervals. The indicator lamps should cycle on and off.
(6) The instrument cluster will automatically exit the self-diagnostic mode and return to normal operation at the completion of the test, if the ignition switch is turned to the Off position during the test, or if a vehicle speed message indicating that the vehicle is moving is received from the PCM on the CCD data bus during the test.