I was having no Starter Motor Cranking issue.
Another Member had posted this info: Above the accelerator pedal is a 4-wire plug with a harness that runs down to under the accelerator pedal and to the transmission tunnel. Unplug it, jumper across the two purple wires in the female plug and try to start again. If it starts, you need a NSS.”
However, the Instructions will tell you if your Neutral Safety Switch is bad but not if it is the Ignition Switch causing the problem.
But, I had never seen that connector or actually done the test.
Pic one shows where the Neutral Safety Switch and the Backup Light Connector is located.
Pic 1 one the location of the Connector.

Pic 2 is a close up of the Connector

Pic 3 is the Connector unplugged, the female part of the Plug goes to the Ignition Switch. So you want to jumper the 2 of the female holes but you cannot tell the holes you need.

Pic 4 In this pic the Yellow Arrows point to the Holes that the Jumper Wires need to go into (bypassing the Neutral Safety Switch) .

If your Starter Motor Cranks you know your Neutral Safety Switch has issues.

If your Starter Does not crank this test still does not tell you if it is the Neutral Safety Switch or the Ignition Switch.

Next you want to see if the Neutral Safety Switch is making contact in Park or Neutral. You can use an Ohm Meter or a Test Light that has Batteries in it. You put the Shifter in Park and probe the 2 male connectors that have the Purple wires going to them. If your Neutral Safety Switch is making contact your Test Light will Light and/or your Ohm Meter will show that you have a connection.

If your Neutral Safety Switch is making Contact and jumper wires on the Connector did not allow the Starter to crank you likely have a Ignition Switch problem.

Unfortunately I found out that what appears to be an Ignition Switch issue can be an issue with what turns the Ignition Switch.
See the below thread if you are interested in that:
Steering Colum Lock (Ignition Lock Housing) causes Ignition Switch Failure

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84 300D, 82 Volvo 244Gl Diesel