What You Probably Know About The Automatic Transmission That Jeep PutIn The '87-'01 Cherokees is that it's one of-if not the-best slushboxes to leave the factory in a Jeep in the last 20 years. It has a decent overdrive and First-gear ratio and is known to outlast even the venerable six-cylinder engines.
What you might not know is that the AW-4 doesn't have a normal Neutral Safety Switch (NSS) but rather a goofy-looking one that controls backup lights, shift points, and overdrive engagement, as well as doesn't allow your Jeep to start in Neutral or Park.
If you're a Cherokee owner, the NSSgoing bad can be evidenced by checkengine codes, such as P0700 (Transmission Control System Malfunction) or P0705 (Transmission Range Sensor Malfunction)- and/or your backup lights aren't working, you have to wiggle the shifter a little or hold it in a certain position to get them to come on, or you have to wiggle the shifter fore and aft to get the Jeep to start, or it starts only in Neutral or only in Park, or won't shift into overdrive ... there are tons of symptoms.
Now, that's all well and good, but why are we prattling on about it? To get the replacement NSS even from NAPA (PN ECH NS5502), it is $339 as of this writing. Sure, you could find it for less, but do you want to cheap-out on a part that controls that many things? We decided to do just that, and for under $10 we had our NSS working like the day our high-mileage XJ left the factory. So, follow along as we show you how to save $329 when your NSS starts having issues.
Electrical-contact cleaner...
Electrical-contact cleaner (brake cleaner might eat the switch), dielectric grease (to lubricate the moving parts and keep oxidation at bay), and fine sandpaper (to clean oxidation and crud off the contacts) are all that's needed for this project, in addition to some basic handtools.
The other side of the switch...
The other side of the switch contains the contact arm, which has two small, springloaded copper contacts. The switch is sealed by an O-ring. We were warned that the contacts like to jump out. The arm was so cruddy, we had to pry the contacts out to be cleaned, sanded, and greased before we could put them back.
Before
After - The service manual...
After - The service manual says to cut a few zip ties, unplug the switch, and slide it out, but that's not as easy as you might think. There were two zip ties on our XJ that we couldn't get to with our knife, the only cutting tool in the garage where we did this. We found that after cutting the zip ties in the engine compartment and unplugging the switch, we were able to unbolt it from the transmission and pull it down far enough for cleaning.
The adjustment of the NSS...
The adjustment of the NSS is the hardest part of this procedure. Some say to put the transmission in Neutral and align the line on the switch with the line of the shaft sticking through it, while others just put it in Reverse with the key on and figure out where the middle of the turn-on/turn-off point is for the backup lights.