Q: truck will not start and cant find the problem might be electrical issue notsure on 2001 GMC Sierra 1500 HD

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truck has new starter , new battery , all fuses have been checked, but when trying to start vehicle nothing happens , lights on dash come on but engine doesnt do anything, what other things can i check for or what might be the issue
(1) Answer
Battery cables/connections.
Ignition electrical switch.
Neutral safety switch if auto.
Clutch interlock switch if man.