1) Check the voltage going to the switch. Verify this with ignition switch turned on and with a voltmeter ( should be around 9-12v if you have an ohmeter). The Hot positive wire will be pink. If there is no voltage on the battery side of the switch, check the wire between the fuse and the switch for being crimped or cut.
2) If there is voltage put the shift lever in reverse and see if there is voltage on the ground side of the switch ( wire is Light green) If there is no voltage then the switch is crapped out.
3) The switch is located on the top of the left end ( driver side) of the trans axle. Unscrew it with a deep well socket, DO NOT use an open-end wrench.
Part looks like this.
ACDelco P/n - 88923666
...welcome
