Where would I find the PnP electrical module on a V6 97 Sable apparently these go after replacing a starter

Is the vehicle security light lit ? It could be a fuse or the starter relay , or even the ignition switch , or even the PNP - park neutral position switch . This is a complex electronic starting system , computer controlled . The ignition switch is a low voltage input to the the BCM - body control module . When the BCM receives this input to crank the engine a lot of complex commands are sent over the serial data network to the PCM to enegrize the starter relay , there by sending battery voltage to the S terminal on the starter solenoid . If your mechanic disconnected the battery it could have caused the radio to say locked , you need a code to enter into the radio to unlock it , may need to have the dealer hook up their factory scan tool to do that .
Your best bet , find a better automotive technician , not a mechanic.
Circuit Description (Key Start)
For ignition switch power modes refer to Body Control System Description and Operation in Computer/Integrating Systems. Once the ignition is placed in the Run/Crank position, the control circuit of the Run/Crank relay is grounded by the body control module (BCM). With the Run/Crank relay switch closed, battery positive voltage flows through it and on to the park/neutral position (PNP) switch. With the PNP switch in either the Park or Neutral position, battery positive voltage will flow to the starter relay coil supply voltage input terminal of the powertrain control module and the coil side of the starter relay. Placing the ignition in the START position sends a message to the powertrain control module (PCM) requesting engine start. If the PCM has determined that the transmission is in Park or Neutral and theft is not active, it will ground the control circuit of the starter relay. Battery positive voltage will then flow through the switch side of the starter relay to the S terminal of the starter solenoid, cranking the engine.

Your look at owners manual or a wiring diagram .

http://www.bbbind.com/tsb-wiring-diagrams-database-results/?type=WD&years=1998&make=50&makeDesc=Pontiac&model=538&modelDesc=Bonneville&system=5&systemDesc=Engine&subsystem=99&subsystemDesc=Charging%20System&docid=7507782

Looking at the wiring diagram i wouldn't suspect a bad fuse , main battery cable to the s terminal on the starter solenoid , starter relay , PNP - park neutral position switch , PASS KEY II theft deterrent module or the ignition switch . Do you know how to use a DVOM - digital volt ohmmeter to test electrical circuit's ?

what do I try next? You take your vehicle to a qualified repair shop. You have no idea of the complexity of the electronic's on your vehicle . Disconnecting battery cables an touching them is not the answer . Having a qualified professional with proper diagnostic tools checking computer system's is . One bad module on the GMLAN serial data network is all it takes for a no start . You have no idea what happens when you turn the key to start your vehicle.

Circuit Description
For ignition switch power modes refer to Body Control System Description and Operation. Once the ignition is placed in the Run/Crank position, the control circuit of the Run/Crank relay is grounded by the body control module (BCM). With the Run/Crank relay switch closed, battery positive voltage flows through it and on to the park/neutral position (PNP) switch. With the PNP switch in either the Park or Neutral position, battery positive voltage will flow to the starter relay coil supply voltage input terminal of the engine control module (ECM) and the coil side of the starter relay. Placing the ignition in the START position sends a message to the engine control module ECM requesting engine start. If the ECM has determined that the transmission is in Park or Neutral and theft is not active, it will ground the control circuit of the starter relay. Battery positive voltage will then flow through the switch side of the starter relay to the S terminal of the starter solenoid, cranking the engine.

Also with power steering warning on ,DTC'S are stored in the control module for the electric power steering an or the BCM - body control module . I have seen bad power steering control modules short out the data bus (network) .
Do yourself a favor an take it to a qualified repair shop.

Hooking up a factory or professional scan tool to see where the crank signal is getting lost at would be the easiest way . You obviously don't know how this works .
Circuit Description
For ignition switch power modes refer to Body Control System Description and Operation. Once the ignition is placed in the Run/Crank position, the control circuit of the Run/Crank relay is grounded by the body control module (BCM). With the Run/Crank relay switch closed, battery positive voltage flows through it and on to the park/neutral position (PNP) switch. With the PNP switch in either the Park or Neutral position, battery positive voltage will flow to the starter relay coil supply voltage input terminal of the engine control module (ECM) and the coil side of the starter relay. Placing the ignition in the START position sends a message to the engine control module ECM requesting engine start. If the ECM has determined that the transmission is in Park or Neutral and theft is not active, it will ground the control circuit of the starter relay. Battery positive voltage will then flow through the switch side of the starter relay to the S terminal of the starter solenoid, cranking the engine.

Your best bet , take it to a qualified repair shop.

Safety switch ? For what ? Park neutral safety switch ,is this what you mean ? Your vehicle not starting ? There is a lot more involved then just that switch.
Circuit Description
For ignition switch power modes refer to Body Control System Description and Operation. Once the ignition is placed in the Run/Crank position, the control circuit of the Run/Crank relay is grounded by the body control module (BCM). With the Run/Crank relay switch closed, battery positive voltage flows through it and on to the park/neutral position (PNP) switch. With the PNP switch in either the Park or Neutral position, battery positive voltage will flow to the starter relay coil supply voltage input terminal of the powertrain control module and the coil side of the starter relay. Placing the ignition in the START position sends a message to the engine control module (ECM)/powertrain control module (PCM) requesting engine start. If the ECM/PCM has determined that the transmission is in Park or Neutral and theft is not active, it will ground the control circuit of the starter relay. Battery positive voltage will then flow through the switch side of the starter relay to the S terminal of the starter solenoid, cranking the engine. For remote vehicle start (RVS) information, refer to Keyless Entry System Description and Operation.

I suggest scanned the ABS module in order to know fault codes stored there. Just with this code number could send you solution details. Could be a probem with the sheel speed sensor misadjust, but will need confitm with the codes finded.

Check properly the ignition cable that goes the the starter solenoid. Is there power on that big cable on the starter? Try to bridge with the ignition cable there. It should crank.

Starter are one of the easier mechanical engine parts to change.

1) DISCONNECT THE BATTERY.
2) Disconnect the electrical cable running to the solenoid on the starter.
3) Remove the two bolts holding the starter in place.
4) Pull the starter out.

To install another starter, do the above steps in reverse order in reverse.

Try shifting the transmission to neutral and try starting the engine, if it starts, the gear position sensor is bad, which is very common on this car.
Or, the starter may be bad, not common, but possible!

Bret
RepairPal.com

Looking at a wiring diagram an using a DVOM - digital volt ohm meter an testing the electrical circuits is the proper way to diagnose , not just replacing parts . If you do not know this ,your best bet , take it to a qualified repair shop. What engine ? 2.4 or 3.3 L .... Starter motor relay , PNP - park neutral position switch . B+ voltage at fuse # 9 40 amp. location - integrated power module .Just Replacing modules isn't the way , may need to be programmed -DEALER . Do you know what a starter relay is an how it works ?
How to Test and Troubleshoot Starter Problem