Cleaning your AW4’s NSS

If the reverse lights on your XJ have stopped working, or only work some of the time, your Neutral Safety Switch (NSS) could need to be cleaned. The NSS is what controls your reverse lights as well as what keeps the engine from being started in any gear other that Park or Neutral (hence the name). Having the dealer replace the NSS will cost you between $300-$400, so doing this yourself can save you a bundle!

First thing to do is locate the NSS of course. It’s down on the passenger-side of the tranny. Not the easiest location to work on, but all you really have to do under the rig is get the NSS off the tranny…Now that you’ve found the NSS, you’ll need to remove the 12mm bolt from the top of the switch case, then pry down the tabs on the lock washer and remove the large nut from the switch case.
Next you’ll need to pull the NSS off the tranny. It’s rather stubborn, and you can’t ‘twist’ it off — it’s got to come straight off. Using a great tip I got from the JeepsUnlimited Cherokee forum, I threaded the retainer nut back on a couple of turns, then used a flat head screw driver to carefully pry the NSS off, using the lip of the tranny pan for leverage. This worked like a champ and didn’t damage the unit.
Now you’ll need to go unplug the NSS from the engine bay. The plug is located to the side of the valve cover by the dipstick. The harness will probably be held in by a couple of zipties, this was actually the hardest part of the process — snaking my hand up behind the engine to cut the zipties. One thing I found handy was to tie a length of wire to the plug, so that when I pulled it down and out of the engine bay, I threaded the wire down with it. This will help out later when you need to get that plug back up into the engine bay from below.
This is what the NSS and its harness looks like.
Now that the switch is out of the vehicle, it’s time to take it apart and clean it. There are 6 small Phillips-head screws holding the switch case together. Once you remove these screws you can pull the two halves apart.
With the switch disassembled, clean out both halves with carb cleaner or something similar. I used brake cleaner. Be careful removing the wiper arm, there are two small spring-loaded brass contacts that may fall out, and they’re hard to find if they do… On mine, one of these contacts had gotten stuck up in the wiper arm due to the dried out grease inside the switch.
Once everything is nice and clean, take some very fine sand paper and polish the terminals on the switch half as well as the contacts in the wiper arm.
Now grease the switch parts with some white lithium or dielectric grease and reassemble the switch.Place the switch back on the shaft on the tranny and replace the lock washer, retainer nut, and locating bolt. Here’s where the wire we threaded down earlier comes into play… the NSS’s plug needs to go back up into the engine bay. The the end if the wire around the plug and haul it up. Plug the harness back in!

That’s really all there is to it. Verify the engine will only start with the tranny in Park or Neutral and that your reverse lights are working again. Total time was about 2 hours, taking my time and taking photos. Total cost was a couple of bucks for cleaner and grease. Definitely well worth the time and effort, especially compared to shelling out a couple hundred at the dealership!


30 Comments so far

  1. AW4 Shifting Issues - October 9th, 2010 10:34 am

    […] […]

  2. bill October 13th, 2010 1:45 pm

    Ya pry on the big nut. Yup all that did was strip my threads.

    Thanx for the help.

  3. Rob October 28th, 2010 6:10 pm

    At first using the tranny pan worked. Then I needed more leverage so I used the side of some channel locks which moved the NSS out until I couldn’t pry it with a screwdriver anymore (it was flexing). Now my NSS is stuck and damaged and I have to try and find a way to get it off without damaging the tranny lines before the new one arives. (145$ at Quadratec + 25$ s+h which makes it a 175$ repair) I have even used penetrating oil to make it easier… no dice.

  4. Steve November 20th, 2010 5:59 pm

    Just performed this repair per write-up and it went off without a hitch.

  5. John November 27th, 2010 8:35 am

    Did mine and replaced the starter also, took several hours due to getting the original ties cut to remove harness. Also did it at night with a drop light. Either case, I saved $234.00 plus tax and now my back up lights work too! Thanks for the article.

  6. NSS is out!!! November 29th, 2010 10:56 am

    […] […]

  7. MtnMiss December 3rd, 2010 10:47 am

    Hey, you guys really rock! I have printed out this article (complete with photos, WOW!). I hope my neighbor will feel inclined to take this on. If not, I will give it a shot myself.
    Thanks SO much for your help. I really think this is the problem, as I have gotten it to start now and then while wiggling the gear shift lever and turning the ignition. Wish I had thought of this before replacing the starter! :). Oh well, one less thing to go wrong later on, right.
    Thanks again guys!

  8. Mystery No Crank Problem??? - December 10th, 2010 12:41 pm

    […] […]

  9. shawn December 14th, 2010 3:09 pm

    i just finished doing a fun job cutting the zip ties off…lol..yeah Bill i got stuck with mine and i took their advice and threaded the nut back on and started prying a litle at a time. i loosened it and rocked it back and forth a bit and then pried it again and it popped off nice and easy. i don’t think you are suppose to just strong arm it and pry it enough to strip the threads??? i took mine apart and it was gunked up something good. got that all cleaned up and now i’m about to go back out to reinstall it. wish me luck and thanks for tips and the pics they helped out a whole lot. i will post my findings after i get it installed….by the way in my part of the woods Vernon, BC…i could only find a new neutral safety switch at the dealer and they wanted over $500 for this save me a whole lot of money $$$$$$$$$

  10. 94 XJ won't start - December 30th, 2010 10:35 pm

    […] it doesn't even turn over. If that's the case I'd check the Neutral Safety Switch (NSS) for sure. Often if a NSS is borderline, putting the shifter lever in Neutral or wiggling it around some will […]

  11. xjMan January 8th, 2011 11:53 pm

    You have saved me. Your process worked perfectly. I can not thank you enough. My NSS is working great now and I think it will remain that way for a long time.

    Thanks again.

  12. Drew January 19th, 2011 1:04 pm

    Just wondering if someone could help me out here?
    I have a 92 jeep cherokee sport 2 door 4.0 inline six.
    The thing was running fine besides for it took me two cranks sometimes three to start the rig, once started all was good.
    A month ago i had someone weld my manifold, after doing so my ck engine light came on, the next day my alternator went, i replaced that and put a new battery in and everything seemed fine untill i went out the next day and went to start the thing, it took me alot of cranking but it did start up but was running like crap, backfiring ect so i put chevron in and it seemed to run fine besides for low idle, i would get two putputs out of it like misfiring or something, I ran the rig and shut it off and it started up untill i parked it for the night… the next morning same thing rough start but this time the only thing i got was again the two low idle putput.
    The third day it will not start at all…
    I cked the codes and i got 54…Distributer…I replaced sensor inside, and still no start so i did the cranck shaft position sensor… still no start.
    I have gas to the cylinders and i have spark.
    I know my NSS was going due to no back up lights unless i wiggled the lever, now i cant even get them to come on.

    Would the NSS be the culprit to this? or is it something else like temp sensor? ignition coil not strong enough? IAC or map sensor?

    Someone please help this is not just my toy but my a to b ride.

  13. Drew January 24th, 2011 9:04 pm

    Ok i bybased the NSS and it still will not start…rechecked the timing and that was good, i did find that ground wires to the engine where gone so i replaced them.. now when i go to start it the only way i can even get the thing to fire i to hold down the gas and then all it does is sorta run like it wants to but it doesnt have enough gas to keep going or like something is telling it dont run and as soon as i let off the peddle it stop running…is it my ecm????

  14. xjfan07 January 30th, 2011 10:33 am

    New prices: Jeep Dealer $335, NAPA/Echlin $290, Quadratec $139, Jeepin Website info $0!!! Works awesome! Just take your time and clean and pre-lube b4 attempting removal. Once its off and split be careful with the two small contacts that r backed by two TINY pressure springs. The grease in mine was so dry and waxy they were seized but once loosened w/solvent they float freely.Take the time and clean and relube b4 reassembly. Note:what is the torque spec on the large shaft nut? Anything much over finger tight and My linkage starts to bind. Hope this helps. Keep JEEPIN!

  15. sometimes1979 February 15th, 2011 7:15 pm

    I cleaned and re-installed the NSS and its still throwing a code for the NSS…any ideals?

  16. Isaac90XJ February 26th, 2011 12:05 am

    I cleaned the NSS and put it back in so now it will start but now when I start it, it grinds during and after starting REALLY LOUD. What could be causing this? I am going to replace the starter tomorrow.

  17. Gudde March 20th, 2011 7:11 pm

    Did mine today without removing the harness. Really wasn’t that bad leaving it hanging.
    Works great now. Thanks for the tip!

  18. Freppo April 4th, 2011 3:10 am

    Did mine yesterday. The reverse lights didnt light up.

    Works perfect now!

    Thanks for excellent instructions!

    Fred (Sweden)

  19. Zakk June 30th, 2011 4:06 pm

    Dont know if it was before or after the prying, but mine came out in about 16 pieces. 255.00 later wishing i owned a

  20. 98Classic July 31st, 2011 4:19 pm

    Well I just finished doing mine and it wasn’t even close to being simple. My uncle owns a garage, so I used that. Upon meeting him he said “Go buy a new one”. Heeding his word, I made a trip to AutoZone, $280 later I was at his garage again. I disconnected the plug from the harness. Jacked up the Jeep and away I went. Remove the bolt, that was easy. The removed the nut. Ok it’s not budging, I’ll use the screwdriver under the nut to pry it loose. Yah no. Ripped the nut right off of the threads. Ok, some 2.5 hours later the smashed NSS is out of the transmission. Then for those pesky tie wraps, the dude that designed the routing and tie wrap locations should be shot. Cleaned the shaft and for those who haven’t tried this, it was rusted/corroded on. Used the wiring trick, though I dropped from inside the engine compartment and routed the cable to the left of the transmission dip stick.

    This job may not be for everyone. Did I save $$ yes. Would I do it again, hard to say, hoping I never have too that’s for sure.

  21. Bob Stone October 10th, 2011 1:49 pm

    Did mine yesterday. Tips: There are two tie wraps, the one closest to the tranny is hardest. Reached up there with needle nose and crushed the joint where the tie wrap inserts into itself.

    The one inside the engine compartment would be even harder but I managed to get my hand down there and “walk” the tie wrap up high enough to get at it. Whew!

    Then get some rope, tie a knot in the end then use electrical tape to secure the rope to the plug. Use the rope to fish the plug. I thought there is no way it would come back after all the trouble I had getting it out but it ended up being easier it fish it back than it was to remove it.

    About 2½ hours total for an amateur like me and it didn’t solve the problem I had of no back up lights. The Jeep starts fine in Park & Neutral but have PO700 PO705. This fix didn’t fix it but cost nothing to try.

  22. Tad February 18th, 2012 6:10 pm

    Did the cleaning to day. fixed the problem Thanks.

  23. Jeep not cranking over sometimes August 16th, 2012 6:33 pm

    […] "everytime" will become not at all. Here's another link for your NSS Rebuild… GA_googleFillSlotWithSize("ca-pub-3927874040083090", […]

  24. David Woods October 1st, 2012 2:28 pm

    Wow! Thanks so much. It only took me an hour and a half and I’m not that mechanically inclined. I already had carb cleaner and light bulb grease so it cost me nothing. This was a big help.

    At first, it wouldn’t start. I disconnected the battery for 10 min. and ran the shifter up and down real fast 10 or 20 times and prayed. Not sure which one worked, but after that, it cranked up first time, and every time since. And my B/U lights work. I can’t believe it. They haven’t worked in over 3 years. Now they work every time. I also had one of my spring-loaded wiper arm contacts stuck down and the other stuck about mid-way. Cleaned right up, and they’re nice and springy now. Thanks again.

  25. MK December 5th, 2012 11:51 pm

    I found the easiest way to pry it off is to use two flathead screwdrivers from both sides. the one towards the rear needs more power than the front and make sure not to pry the front much further than the rear side since it is essentially held toward the rear with the 12 mm removed. It may help to clean off the sludge on the ledge beneath and around the rear side as well.

  26. Tom Roney September 2nd, 2013 10:26 am

    Thanks very much for the great article! I fixed my NSS yesterday. I had a hard time freeing the switch, but after some gentle prying with two screwdrivers behind the body of the switch and also the prying behind the large nut, I was able to free it.

    One of the six srews on the switch body was seized and the head broke off. I was able to drill it out and re-tap the hole for a new M4(0.7 thread)x15 screw.

    I found the torque specs for the adjusting bolt (the 12mm head one at the top). It is torqued to 13Nm (9 ft.lbs.)AFTER you tighten the large nut to 6.9Nm (61 in.lbs) and bend the locking tabs back against the nut.

    The Trans is best left in Neutral (don’t forget to block the tires!)while you do this, so the shaft in the center of the large nut lines up (long ways)with the neutral position line scribed on the switch body. Tightening the 12mm bold last allows you to fine tune the allignment, as the bolt hole is elongated for this purpose.

    Your article saved me a few hundred bucks and my back up lights work great now! Thanks again!

  27. Reverse lights not working September 9th, 2013 2:51 am

    […] lke the NSS is acting up. Hope this Write Up will help… […]

  28. johnson October 27th, 2013 8:57 pm

    I just run wires to the b/u lights to a switch so I can turn them on anytime I want and only took me about an hour to do it

  29. […] […]

  30. Thomas Adair September 4th, 2016 1:54 pm

    Can someone tell me if this is this the same on a 1998 Jeep Cherokee Classic 2wd 4.0 W/I-6 engine as it is on a XJ? Thanks!

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