I have a 99 24valve with an NV4500 that will occasionally not start. Not starting isn't even the half ot it, it won't turn over and even try to start. Its as if I have no power from the battery. Starter was replaced in December, alternator I just replaced a few weeks ago and both batteries have tested good.

Until recently I was able to get it started intermittently, which led me to question the starter switch.

So my question is, what are symptoms of a bad starter switch?

 

With the truck being a manual maybe your clutch pedal switch is malfunctioning. I had some chaffed wires down there on mine.
Do you get all the lights on the gauge cluster when you turn the key?

 

Here are the pics under the dash of my truck.

 

Yes, I do get lights on the dashboard. The switch is what I was suspecting, Is it supposed to be connected to anything? The harness is plugged in but i'm able to physically pop the switch off the rod.

Culprit?

 

It should have a clip that holds it to the shaft. I still have the original interlock switch on mine. they don't usually go bad in my opinion. but if it is not secure that may be the problem. Also with a tilt steering column some times the wires get damaged in the column from many up and down movements can cause everything from OD problems to turn signal issues key switch issues.
Also check your start relays by swapping them in the Integrated power module (IPM fuse box) and check the plug there too.

 

Alright so I ran a jumper wire in the position of the starter relay and my truck fired right up.

So that narrws it down to either the starter switch or the relay, correct?

 

Did you bypass the NSS?

 

I had the truck in neutral so, I believe so?

 

I believe you can swap the relays around in the IPM and eliminate the relay. If that doesn't work check the Safety switch by jumpering it.