Okay, apologies I'm new to the mechanic world and am doing this on my own. Thanks for the advice.

 

How would I test it? I have a multimeter but not sure how to test that switch.

 

Begin by trying to start in neutral instead of park...

With the selector in park, check for continuity across the NSS where the two red/blue wires would attach.

 

Yes, just like Jim explained - with the selector in P, crawl under there to the switch... unplug it from the harness... probably 4 wires - two that are red/blue, prolly one black/purple (or pink) maybe two that are that color code - bk/p are the backup lamps, you don't care about those right now.

Set your meter to some OHMS scale, doesn't matter which one (jim - he likely has no idea what continuity checks are). Now cross the red & black leads, the meter should read zero; uncross and they'll read something else - one? Some non-zero value - UNLESS I HAVE THIS BACKWARDS, but...

Point is, the meter shows different readings for connected and unconnected probes.

Now... put one probe into one of the red/blue wire connectors OF THE SWITCH, and the other probe into the other red/blue connector OF THE SWITCH... meter should be reading zero - zero ohms resistance.

Now crawl back up top and move the shift lever out of P, put it anywhere except N and the meter should be showing non-zero value.

Do the same test for N.

This shows you if the switch is working or not.

Once we know the answer to this, we'll see if we need to do voltage tests or not.

Hope I'm not confusing you, I totally forget what the meter shows sometimes but the point is, different readings for crossed and uncrossed probes.

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Thanks for chiming in, Jim! And please correct me if I'm wrong anywhere, you're one of the ones I rely on to do that.

 

No need to apologize, dude, not at all! I'm just trying to help by explaining the thing on the dash has no bearing on anything functional, that's all.

 

Chris,
Your explanation is spot on.
Consise and much more detailed than mine.
A digital meter will usually read -OL- when there is zero continuity.
A analog meter will be pegged on infinity -∞-

It could be as simple as that plug came loose or is really dirty.

Sometimes if the NSS gets wonky you will be able to start the vehicle in neutral.
This can keep you mobile until there is time to fix it. (I know my ex had to do this for a week until I could get the part)

 

The only thing I would add is BE SURE TO CHOCK THE WHEELS if you are going to shift out of park, before you even think of crawling under the truck.