Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
I see you replaced the ignition switch, but no Lock Cylinder is listed.
If fuel and crank are both inoperative, the PassKey system most likely has a problem.
There are two possible PassKey systems, Test the security light and see if it detects a problem.
Check Security Indicator Lamp
The tiny wires going from the ignition lock cylinder will break and the vehicle will not start. They run down through the column to a connector at the base of the column. Even with a new key with the correct pellet, if these wires have broken, it will not start.
Here's a quick test you can make on these tiny wires. Measure the resistance of the key pellet. Then place the key into the lock cylinder and go to the base of the column and unplug the connector from the lock cylinder and measure the resistance from there. Should be within about 10 ohms of what you measured at the key.
CRANKING/FUEL INTERRUPT The theft deterrent system prevents starting (cranking) of the vehicle, and fuel delivery to the engine, when using any key other than the special electrically coded ignition keys supplied with the vehicle at new car delivery.The cranking/fuel interrupt function of the system operates independently of the alarm system and provides protection even if the alarm system is defeated or the vehicle is left unlocked.The system requires no active involvement from the operator to function.When the operator turns the ignition "OFF," cranking and engine fuel delivery are automatically disabled.Inserting the properly encoded key into the ignition signals the CCM to permit cranking and to transmit a "fuel enable" signal to the ECM, which in turn permits fuel delivery to the engine.If the key used does not have the proper electrical coding (unauthorized starting), the CCM will reset for two to four minutes (crank and fuel disabled) and not permit starting during this period even with the proper key.To start the vehicle, the key must have the correct mechanical and electrical coding. The ignition cylinder contains electrical contacts used to "read" the ignition key.
There are three types of theft deterent systems that may be available for these car lines.
NOTE: Either PASSkey(R) I and PASSkey(R) II may be used in 1992 vehicles. PASSkey(R) II systems are identical to PASSkey(R) I systems with the exception of some additional self diagnostic capabilities and differences in connector terminals. The correct system can be identified by referring to the wire color codes on the theft deterrent module. It is important to note that the Universal Theft Deterrent (UTD) system may be used in addition to OR in place of the PASSkey(R) systems. Refer to the individual systems in order to differentiate which systems needs to be diagnosed. These systems are diagnosed separately.
Both PASSkey(R) systems can be identified by examining the ignition key for the embedded resistor pellet
Universal Theft Deterent (UTD) can be identified by refering to the RPO label located on the vehicle. Refer to diagram for location of label by carline  .
Remarks:  Regular production option code label for parts ordering reference.  Carline refers to the 4th digit on the Vehicle Identification Label (VIN).
If you have any questions, let me know