How do I change the ignition cylinder on a 97 Chevy c1500 if can't turn key to on/run.

replace ignition cylinder

It is your VATS anti theft system that is giving you fits. You have two choices, get a locksmith to change the pins in your new lock cylinder to your old key and use the original key with the proper chip for your VATS system, or get a hold of a shop that installs remote start systems and have them bypass the VATS system

When the key switch is off and the engine is not running, do you have power to the coil ? Could be a problem with the key switch.

Check the ignition switch located under the dash on the steering column. Listen if you here a click from that location when you first turn the key on - if no click then replace the switch.

THE IGNITION SWITCH HAS TO BE IN THE START POSITION.INSERT 1/16 INCH ALLEN WRENCH PRESS THE LOCK CYLINDER RELEASE PIN AND ROTATE THE KEY TO THE RUN POSITION.AND PULL THE LOCK CYLINDER OUT.WHEN INSTALLING THE NEW CYLINDER ALIGN THE RETAINER SLOT IN THE HOUSING THEN PUSH THE CYLINDER IN UNTIL IT SNAPS IN POSITION.

Do a compression test...may be a valve issue.
Good luck, Td

When you changed the cylinder, you also changed the key, in the key is a chip the allows the antitheft to turn off and you need to reset the antitheft to the new key. A dealer job unfortunatly.

If it's the ignition lock cylinder, there is a screw/pin behind the steering wheel. You'll have to remove the wheel lock retaining ring and plate. You'll see the screw just above or below the lock cyl. If I remember, it's about a 5/15 socket that fits it. Oh yea, the key will have to be in the "run" position to remove the cyl.

Add Duplicate Key (PK3 or PK3+ key)
1. Insert an existing key into the ignition cylinder.
2. Turn the ignition cylinder to ON (RUN) and back to OFF.
3. Remove the existing key and, within fifteen seconds, insert the new key
and turn it to ON (RUN).
4. The security light will light up for two seconds to indicate success in programming
the key into the vehicle.
Originate New Master Key (PK3 or PK3+ key)

1. Insert new key into ignition cylinder and turn it to the ON (RUN) position.
The security light on the dash will illuminate and stay on for ten minutes.
2. When the security light goes out, you have one minute to start the next
step. Turn the ignition cylinder to OFF and then back to the ON (RUN)
position. The security light on the dash will illuminate and stay on for ten
more minutes.
3. When the security light goes out, you have one minute to start the next
step. Turn the ignition cylinder to OFF and then back on the ON (RUN)
position. The security light on the dash will illuminate and stay on for ten
more minutes.
4. After the security light has gone off the third time, the key has been programmed
into the vehicle’s computer and will operate the car. It has replaced ALL the
previous electronic key codes and is the ONLY key programmed into the
vehicle’s computer.

Add Duplicate Key (PK3 or PK3+ key)

1. Insert an existing key into the ignition cylinder.
2. Turn the ignition cylinder to ON (RUN) and back to OFF.
3. Remove the existing key and, within fifteen seconds, insert the new key
and turn it to ON (RUN).
4. The security light will light up for two seconds to indicate success in programming
the key into the vehicle.

If you just need an ignition key, take your title and ID to a Chevy dealer. They may be able to provide you with new keys.