If you hear some clicking sounds when you turn the key to "on" without starting the car, and the "firm ride" light is blinking 1, 2, 3, or 4 times it is because one of your ride control actuators is not functioning correctly or it has gone bad. Count the clicks, or blinks. 

The ride control actuator code is as follows:

Driver's side rear (1 click/blink), 
Passenger's side rear (2 clicks/blinks), 
Passenger's side front (3 clicks/blinks), 
Driver's side front (4 clicks/blinks). 

So, if you get 2 clicks it would be passenger's side rear control actuator that is sending the signal.

If the clicking sound and/or blinking light flashes constantly, the ride control computer is bad and it will need to be replaced.

If you have determined that a ride control actuator is malfunctioning, you need to find out if it is actually bad! 

On the front, the ride control actuators are covered with a black plastic cover which can be easily removed. The rear ride control actuators are located on the top of the shocks and can be accessed from the trunk rather easily.

With the key in the off position, remove the clover (Front). Once removed, you will see the ride control actuator mounted to the top of the shock.

Make a mental note of the small blade-like pin on the actuator and its position relative to the white plastic clips on the actuator. 

To remove the ride control actuator squeeze in on the 2 white clips on the top of the actuator. Once removed, look down the center hole of the actuator. Inside you will see the small blade-like pin more clearly. 

To clean the ride control actuator use brake-cleaner or a light penetrating oil such as WD40. Spray all around the small blade pin and let it penetrate for a few minutes. Then take a pair of small needle nose pliers or a small screw driver and GENTLY rotate the blade back and forth about a half turn (there is NO need to rotate it completely). If the actuator is stuck or dirty, the blade pin will not turn easily at first. DO NOT TRY TO FORCE IT. If it won't turn with VERY LIGHT PRESSURE, repeat the use of brake-cleaner or a light penetrating oil and let it penetrate a bit longer. Repeat this process until you can turn the blade back & forth easily. 

Now that it is clean and ready to test, put the blade pin back into the location where it was when you took it off, and replace the actuator. This can try your patience, because it has to line up perfectly for the actuator to be snapped back on. DO NOT FORCE IT back on. It will snap right in easily when it's lined up properly.

After everything is installed, turn on the key and see if the flashing light has stopped. If it does not, then the actuator will most likely need to be replaced. In some very rare cases you may actually need to replace the shock.

99% of the time it is just a matter of cleaning up the actuator and freeing up the blade pins because they collect dust and road grime.