The reason for turning the Steering wheel staight, is to access the rear part of the steering wheel & for a starting point when you put everything back together.You can mark components as you go also
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Auto Mech / Electr&onics
Chevrolet Cert., Heavy Line Mech, Race Shop Owner, Mobile Electronics.
If the wheel is straight, then Disconnect the Positive battery cable & follow the instructions for disabling the SIR.
Then remove Steering Wheel