If all is well your car will start in Park or nuetral. The symptoms you describe indicate that you may have a failing PNP switch. When it starts to go bad the starter may or may not engage in P or N. Many 960/S90 owners have found that a temporay cure is to run the shifter from P down to L and back again about 15 times, this may clean the contacts and allow you to start. Another technique is to hold the key in the start position while rocking the shifter through the gears until the starter engages as you pass through P or N.

The PNP is mounted on the right side of the tranny, it is a common failure on the 960/s90 models. There is info on this in the FAQ section.
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David Hunter