There is no NSS. The AW50 uses range sensor to know what gear it's in. The range sensor is on top of the transmission, and it's what the shifter cable is connected to.

IMO some of the best tutorials you'll find are from the Volvo community, where it's often referred to as the PNP switch (park neutral position switch).

 

Thanks for that!

It's a big help knowing the nomenclature. Is there a link to show me what this range sensor looks like? I couldn't find anything useful on Youtube using "range sensor ".

Which Volvo community are you referring to?

Is this it?

 

The range sensor is what’s commonly referred to as the Neutral Safety Switch, but Jvanbra’s right that technically there is no NSS on these cars.

 

Yep, that’s what it looks like. Take the battery and the battery tray out and you’ll see it on top of the transmission with the shifter cable attached to it. The transmission dipstick also bolts to it.

 

Thanks! I'm off to "search, remove, repair". I hope "remorse" is not the outcome. Apparently, a new replacement is about $300 + shipping. I'm not sure a used sensor is worth the savings.

 

In 2010, mine died and I drilled out the rivets. The plating on the spring-loaded connectors was badly worn and the grease dried out. I cleaned it all up, and regreased with dielectric silicone grease. Used small screws to reassemble (don’t get anysolvent on the o-Ring gasket, it won’t fit back in its groove.)
The repair lasted a year and started acting up with no starts again. I opted to replace the NSS with an original and it’s been fine ever since.

NOTE: New switch comes set in NEUTRAL. You need to put the car in N before pulling the old switch. That way, you can just drop the new switch onto the transmission link (it has a flat shaft) and hand tighten the bolts while you TEST ITS FUNCTION. Hook up the battery without the tray installed and move gear shift to R. Back ups should light with ignition on, but not started. Move shift to D with someone on the brake pedal and parking brake set and ensure it will not start. If all OK, remove the battery again and reassemble everything taken out. Take a bunch of photos as you do it to be sure and get it right. BEFORE REMOVING THE TRANSMISSION DIPSTICK TUBE, clean around where it mates to the transmission with a rag. You don’t want any dirt falling into the transmission. One of the tougher parts of the process is when you route the cable for the NSS under and around stuff in the engine bay. Photos really help.

I have photos of the process available if you want them. Let me know.
Good wrenching.

 

Mechanically, the sensors are very simple. You should be able to take it apart, clean it, and re-grease it. There are also a couple of ways to bypass it if it’s causing issues with starting your car.

 

Except for the rivets instead of screws, I'm guessing it is very similar to this:

 

It’s fairly similar. It’s mostly just an arm that sweeps over various contacts as you shift the transmission, like the one on that video.

 

Associated question: Does the range sensor also control the back up lights?

 

Yes. It controls the backup lights.

 

Here's where it is on my 2001 9-5 4 cyl. automatic transmission:

For orientation, find the yellow topped transmission dipstick.

 

The 4-speed auto on the early 9-5s has gear selector position sensor with a pigtail connector. The pigtail is potted in place and the wires break with age. You'll get a P0705, usually, when this starts happening. You can try to repair the sensor but you're only delaying the inevitable need to replace it. I had this happen on a 2001 SE; found two intermittent wires in the pigtail. They'd work as long as you pushed the pigtail bundle into the sensor.

The 5-speed doesn't have this problem as the trans position sensor has an integrated socket for a plug on the wiring harness. They are not interchangeable.

 

And to answer your question, yes, the range sensor controls the backup lights. Using the backup lights is a reasonable way to reinstall the sensor properly without the factory alignment tool.

 

Did this repair on my Mrs first 2000 9-5 years ago —straightforward, as per above —reform contacts, clean & re-greased —put together with new screw/nuts. reinstalled —perfect. Way cheaper than buying a new one.