Also the PIM requires a signal from the range selector so give the selector a good back and fourth and try starting it.
VT 304 V8s don't have a PIM, only Gen III V8 and later Chev engines. Refer to the attachment and you will see that the Neutral Start/Backup switch is largely mechanical and is indeed connected to the shift selector. As well as giving the selector a good back and fourth (sic) the OP should try and see if the car starts in neutral. As you have correctly pointed out, the symptoms are similar to what happens when you try and start an auto in a gear other than park and neutral, so the switch could be faulty or the selector could be badly adjusted.
1.2 POWERTRAIN INTERFACE MODULE (PIM)
The Powertrain Interface Module (PIM), is located at the left ’A’ pillar behind the kick panel. The PIM acts as a communication translator between the
PCM and other onboard controllers that use a different serial data protocol. The GEN III PCM uses the new Class II serial data to communicate, while other controllers on the vehicle are designed to transmit serial data via the conventional Universal Asynchronous Receive Transmit (UART) protocol.
Since these two types of serial data are not compatible, a translator or PIM is required to transmit data in either direction between the PCM and other controllers. The PIM will interpret the serial data information and translate UART to Class II or Class II to UART to support the appropriate vehicle Controller operation.
The PIM is the serial data communication translator for vehicle operations. It interprets and supplies the following information in the proper direction for operation of:
• A/C Request.
• Check Powertrain Lamp (CPL).
• Starter Motor Control.
• Theft Deterrent (Starter Motor Control).
• Oil Warning Lamp.
• Power/Economy Lamp.
• Low Coolant Lamp.
• Gear Indicator Lamps.
• Cooling Fan Relay (Low Speed).
