How to Confirm Suspected NSS Problem?

[DonQuiXJote]

Hi all, I'm preparing for a big road trip in about a week (god help me), so naturally my 2000 XJ has decided now is a good time to start giving me some unexpected trouble.
For the past few days, about every other time I try and crank it, all the battery powered stuff clicks on but there's no sound from the engine at all. Wiggle the shifter, it gets going just fine, which made me suspect the NSS. Before I add on to my already pretty big tune-up budget and buy a new one, I wanted to be as sure as possible its the NSS. Again, it cranks up just fine about half the time, isn't throwing any codes, and my backup lights are working.
What's the best way to confirm for sure that it is the NSS? What else might be giving me these specific symptoms? Any advice much appreciated!

 

[DirtySouthXJ]

When it is not starting (shifter in park or nuetral) and without touching the shifter, you can test for continuity (ground) at pin 10 or you can run a jumper wire from pin 10 (strip the end of some wire, insert wire into pin 10, install starter relay) and connect the other end of the jumper wire to ground/battery negative. If it starts every time like that with the jumper wire installed but doesn't start without, it is very likely the NSS. I just went through this recently and there is some more info in my thread here..

https://naxja.org/threads/1996-4-0-no-crank-starter-works-when-jumped.1168088/

In my case, it is almost certainly due to shorted wires at the connector at a minimum and possibly in combination with issues with the NSS itself. My short term plan is to leave the jumper wire connected until I can fix the NSS connector wiring and refurbish the NSS. The jumper wire bypasses the NSS, so it can start in gear though.

 

[dktool]

I put in a momentary contact push button for the rare times my acts up until I get around to fixing it right.

 

[DonQuiXJote]

If it starts every time like that with the jumper wire installed but doesn't start without, it is very likely the NSS.

Yep, starts every time with the jumper and will go right back to no crank when I remove it. Thanks! Looks like I'll have to invest in a new NSS. Do you/anyone else know if that's a doable swap for a relatively inexperienced home mechanic? I've got about a week and change before I hit the road and don't want to be stuck doing something I should've just taken it to a shop for.

 

[DonQuiXJote]

I put in a momentary contact push button for the rare times my acts up until I get around to fixing it right.

Do you mean you run the jumper wire DirtySouthXJ mentioned but just throw a button on along the length? If so, do you run it so the button is in cabin?

 

[Saudade]

You can disassemble and clean the NSS to restore proper function. Disassembly and cleaning it is relatively easy. Getting it off the trans is the hard part. Part of the shaft protrudes through the NSS. It can get badly corroded and make life difficult.

On my pic, you can see the shaft with the 2 flats. That goes into the trans. The big nut clamps the wiper arm (inside the NSS) to the shaft. You should soak it with some good penetrating fluid for a while before you attempt to remove it. Of course, if you buy a replacement, you won't need to worry about cracking it.

Plenty of YT vids on replacing it. Don't forget to adjust it so it will still start in P &N and verify your backup lights work.

 

[dktool]

Do you mean you run the jumper wire DirtySouthXJ mentioned but just throw a button on along the length? If so, do you run it so the button is in cabin?

I ran a 2 wire lead into the cabin, push button connected in parallel with the 2 wires that go to the nss.

 

[Saudade]

So you have to press and hold the button while you turn the key to Start?

 

[dktool]

So you have to press and hold the button while you turn the key to Start?

Yes

 

[lawsoncl]

Lookup the Bleepin Jeep NSS videos. He does a pretty good job showing how to remove and refurbish the NSS. Hardest part is getting it off. Note the back is plastic, so don't jam a bar under it and pry as you will break it.

 

[DirtySouthXJ]

Yep, starts every time with the jumper and will go right back to no crank when I remove it. Thanks! Looks like I'll have to invest in a new NSS. Do you/anyone else know if that's a doable swap for a relatively inexperienced home mechanic? I've got about a week and change before I hit the road and don't want to be stuck doing something I should've just taken it to a shop for.

I'm planning to just leave the jumper wire installed until I can repair the damaged harness wiring on my XJ. Being that it is just a supplemental ground, I can't see any downside other than being able to start in gear; but I've never, not even once attempted or accidently attempted to start the vehicle in gear. Of course, refurbishing/repairing/replacing the NSS (or connector/wiring in my case) would be best, but in a pinch with limited time etc. the jumper wire should be able to get you where you need to go until you can take the time to do it right.