It is really easy to remove the FICM. Just disconnect your batteries to begin. The FICM is located on the driver's side typically under and to the passenger side of the coolant overflow reservoir. There are two workable methods to remove it.
Without draining coolant method (provides less room to work, but is faster):
1. After letting the engine cool, remove and reinstall the reservoir cap to eliminate any built up coolant pressure.
2. Remove the two bolts holding the reservoir in place.
3. Using a plier, remove the hose clamp on the upper portion of the reservoir that is on the passenger side of the reservoir near the top. Set the hose aside, pointing it upwards to avoid coolant loss. Pull reservoir as far to the driver's side as possible to provide FICM screw access.
With draining coolant (dramatically more room to work):
1. Drain perhaps a gallon or so out from beneath the radiator (the petcock valve is located on the driver's side)
2. Remove the two bolts holding the reservoir in place
3. Use a plier to remove the clamps from the hoses connecting the reservoir to the various hoses (on the underside and the upper passenger side). Set reservoir aside.
Common Next Steps
Regardless of which method you used above, you will now notice that there are four bolts holding the FICM. Remove these and then lift up on the FICM and note the three wiring harness plugs. First, push the plugs FURTHER IN to relieve any pressure against the clips. Then, squeeze each plug one at a time one at the base on the long edges and then pull these plugs straight down or wiggle them to and fro to get them out. That's it. The two bolts on the front are nearly always 10mm. The two in the back are difficult to see, but are 8mm.
If you experience diffculty getting the plugs to come out, some have reported luck using a pair of channel locks to GENTLY squeeze on the base of the locking connector and then wiggling the plug side to side in order to get it out.