How to replace the ignition on a 1991 oldsmobile cutlass cierra

If you mean the ignition lock cylinder:

Ignition Lock Cylinder CAUTION
If the car is equipped with an air bag, do not service the steering column or dashboard components. Extreme danger of air bag deployment exists even with the battery removed! Serious injury could occur. REMOVAL & INSTALLATION Without Air Bag

1. Place the ignition switch in the RUN position.
2. Remove the lockplate, turn signal switch and buzzer switch.
3. Remove the screw and lock cylinder. NOTE: If the screw is dropped on removal, it could fall into the column, requiring complete disassembly to retrieve the screw. To install:
   
4. Rotate the cylinder clockwise to align cylinder key with the keyway in the housing.
5. Push the lock all the way in.
6. Install the screw. Tighten the screw to 14 inch lbs. (2 Nm) for adjustable columns and 25 inch lbs. (3 Nm) for standard columns.

1. Turn the steering wheel so the vehicles wheels are pointed straight ahead.
2. Place the ignition switch into the LOCK position to prevent undercentering of the coil assembly.
3. Disable the SIR system. Disconnect the negative battery cable.
4. Remove the coil assembly retaining ring, then disconnect the inflatable restraint coil assembly. Let the switch hang freely if removal is not needed. To remove the coil assembly proceed.
5. Remove the wave washer, then the shaft retaining lock ring with tool J-23653-SIR to push down on the shaft lock. Dispose of the ring, it is not reusable. Fig. 1: Special tool J-23653-SIR or equivalent is required for pushing down the shaft lock to remove the shaft ring
   
6. Remove the shaft lock, then disconnect the canceling cam assembly.
7. Remove the upper bearing spring, race seat and race.
8. Position the turn signal to the right turn (up) position.
9. Remove the multi-function lever and hazard knob assembly. Unfasten the round washer head screw and signal switch arm, along with the turn signal switch screws.
10. Remove the turn signal switch assembly by unfastening the connector from the bulkhead connector. Gently pull on the harness through the column and disconnect.
11. Make sure the coil assembly does not become uncentered, this could happen if the centering spring is pushed down letting the hub rotate while the coil is removed from the steering column.
12. Remove the inflatable restraint coil assembly with the wiring harness from the column assembly.
13. Remove the wire protector, then attach a length of mechanics wire to the coil terminal connector to aid in reassembly. Then gently pull the wire through the column.
14. Remove the key from the steering column lock cylinder set, then remove the buzzer switch assembly.
15. Reinsert the key into the lock cylinder, turn it to the LOCK position.
16. Remove the lock retaining screw, then the cylinder. To install: NOTE: Make sure all fasteners are securely seated before applying the necessary torque. If you fail to do so, component damage or malfunctioning of the steering column may occur.
    
17. Install the lock cylinder assembly, insert the retaining screw, then tighten to 22 inch lbs. (2.5 Nm).
18. Insert the key into the lock cylinder. Install the buzzer switch assembly. Turn the key to the LOCK position.
19. Install the turn signal switch assembly wiring harness through the column, let the switch hang freely. Connect the wiring to the bulkhead.
20. Insert the coil assembly wiring harness through the column letting the coil hang freely. Attach the turn signal assembly with the binding head screws. Tighten the screws to 30 inch lbs. (3 Nm).
21. Attach the signal switch arm with the round washer head screw, tighten the screw to 20 inch lbs. (2 Nm).
22. Install the hazard knob assembly and the multi-function lever.
23. Install the inner race, upper bearing race seat and spring. Attach the turn signal cancelling cam assembly, apply grease for lubrication.
24. Replace the shaft lock and install a new shaft lock retaining ring. Use tool J-23653–SIR or equivalent to push down on the shaft lock. The ring must be firmly seated in the groove on the shaft. NOTE: Set the steering shaft so that the block tooth on the race and upper shaft is at the 12 o'clock position. The wheel on the car should be straight ahead. Set the ignition switch to the LOCK position, as this will ensure no damage to the coil assembly.
    
25. Install the wave washer, then attach the coil assembly, make sure it is centered correctly. Fig. 2: Centering the coil assembly is important in assembling the column assembly
    
    
26. Attach the coil assembly retaining ring, the ring must be firmly seated in the groove on the shaft.
27. Gently pull the lower coil assembly, turn signal, and pivot (pulse) wires to remove any kinks that may be inside the steering column assembly. If you fail to do this you can damage the wiring.
28. Complete assembling the steering column assembly.
29. Attach the negative battery cable.
30. Check the functions of the turn signal, make sure it cancels when turned on and the steering wheel is turned.
31. Enable the SIR system.