OK, yes another nss question. My mom went to have her 98 Cherokee inspected, no reverse lights. After googling, and coming here a lot, I narrowed it down to the nss( as she had starting issues with it before). Got under there, and was adjusting it. Got the back up lights on, twice. But.. the second time, when I tightened it, I didn't have it as tight as I thought. The lights went off when she put it in another gear, and didn't come back on in reverse.. So I loosened it again, and am now having absolutely no luck at all getting them back on with adjusting. It will still start just fine. And we know at that time it was the nss, as when I adjusted it, they came on, obviously. So, anyone have any ideas or tips that may set me in the right direction again? I am so ticked at myself that I didn't get it tight enoughinitially, as they worked. Bah! Lol

 

Your prob going to have to take it apart and clean the old grease out. What happens over time the heat from the exhaust and transmission hardens the grease to were the arm gets blocked so to speak and doesn't allow the signal or voltage to get where is going.

 

Recently did mine. Hardest part was getting the factory zip ties cut. One small tip. I put the two SMALL springs that are under the contacts on a safety pin to clean them with carb cleaner.


http://www.xjtalk.com/showthread.php?t=1747


If needed,when your ready for installation this helped me get it right the first time (THANKS to 1991 Jeep Man where ever you are):

"At this point, your N.S.S. is refreshed and ready to reinstall on your rig.
Make sure you have a tad bit of dielectric grease smeared on that shaft coming out of the transmission. It will assist when you push the N.S.S. back on the shaft. Next, note how the blocked portion of the shaft is oriented and rotate the contact arm so the threaded collar matches it (square peg in a square hole). Line the N.S.S. up on the shaft, and firmly press it straight onto the shaft. This is the only way to do this! Work with it and it will go on. It is on when the outer housing of the N.S.S. is almost flush with the outer rim of the transmission pan. If you need to, take your screw driver and give a few gentle taps with the butt of it on various spots of the N.S.S. If need be, use the end of the screw driver on the mounting nut to gently give it a tap or two (last resort).
Once the plug is in its location, plug it in and use a zip tie or two to secure its harness to some stable location/other wire to give it some stability.
Go back below to your N.S.S. and very lightly install that mounting bolt. Then very gently install the mounting nut onto the threaded collar/shaft. I say gently because there is some more guess work here. You will notice the hole in the housing that the mounting bolt goes through is elongated to allow for adjustment of the N.S.S. I put mine kind of in the center and then lightly tightened the mounting bolt down. Get the mounting nut on the shaft just a tiny tad over finger tight. Go in your Jeep and try shifting the transmission. If your shifter is suddenly more difficult to shift, then either the mounting bolt or the mounting nut is too tight and causing the N.S.S. to bind on that shaft which also goes through the other side to your shift cable. At this point it is a game of Up-And-Down. Get everything nicely tightened and adjusted until the shifter is smooth like it was before. Then turn your key to 'ON' (not start) and put it in Reverse. If your Reverse lights work, one check. Put the Jeep in Park and try to start. If it starts no problem, another check. Turn it off, go in Neutral, and try to start. If it once again starts fine, then you are good to go and you have everything good to go! Make sure your mounting bolt is snug (doesn't need to be crazy) and your mounting nut hand tight. Then take your flat-head screwdriver and bend up the tabs on that lock washer to secure the mounting nut in place and prevent it from spinning."