AW4 problem

[MJR]

I'm a little leary of aftermarket scan tools and what they are capable of. I work at a dealer have use the factory scan tools. If you want to I will try to help you over the net to diagnos the problem as best I can. It would be nice if you could find someone at a local dealer that you could smoose into at least pulling codes (you'd have to put it back the way it was first as in 98 controller, do a battery disconnect, and drive it for a little bit before) for you (without charge) in the engine/trans and telling you what they are so I could help better.

 

[Evan463]

definatly, cant tell you enough how much i appriciate the help, i had a friend in a dealer but due to cut backs that dealer has been shut down ill try looking him up again and seeing if he got in somewhere else but. see what i can do. im going to tear down the nss sat morning cross my fingers see what happens ill post back sat night or early sunday. thanks again

 

[MJR]

Let me know and if you need anything. I can walk you through testing each circuit if need be.

 

[lawsoncl]

The wiring does show a 98 as having 2 speed sensors but for some reason the parts catalog says the 98 TCM is for a 98 only.

I believe the sensor change was in 97. More than likely the only difference is shift points or other minor programming changes. If you have a meter, then you can check quite a bit at the TCU connector. http://www.transonline.com/transdigest/magazines/1997-10/Shift%20Pointers/index.html for some info there.

If you suspect a bad NSS (and the no-crank definitely points in that direction), then it can be cleaned. Checkout http://www.go.jeep-xj.info/HowtoNSSrebuild.htm or http://jeepin.com/features/nss/index.asp. If you break it getting it off, http://www.teamgrandwagoneer.com/cgi-bin/partsSQL/search.cgi?query=neutral has replacements for $149.

 

[kastein]

Problem is it's for a 99-01. The 98 one is specifically only the two #'s I gave you. It DOES NOT supercede to an "AB" part #. This may because in 99-01 AW4's use 2 speed sensors for the trans controller vs. 1 on 87-mid98/99 and the 99 TCM is looking for a sensor you may not have on your trans.

Dielectric grease, special for electrical contacts.

This confuses me - my 96, the 90 aw4 I have, and the 96 aw4 I got as a parts donor/rebuild guinea pig all have an output sensor but not input sensor (the transmission housing has the mounting boss cast in for the input sensor, but it's not machined out or populated.) The 98 I just got that I'm swapping the 96 output sensor/rotor over to in preparation to installing it in my 96 XJ has both input and output sensors. So I think the 98-01 use two speed sensors while 97-down use only the output sensor.

One thing I find useful in identifying 97+ TCUs is that they have both the two digit model year they were intended for at date of manufacture and the full 8digit + 2 alpha (revision ID) MOPAR part number on them.

 

[MJR]

This confuses me - my 96, the 90 aw4 I have, and the 96 aw4 I got as a parts donor/rebuild guinea pig all have an output sensor but not input sensor (the transmission housing has the mounting boss cast in for the input sensor, but it's not machined out or populated.) The 98 I just got that I'm swapping the 96 output sensor/rotor over to in preparation to installing it in my 96 XJ has both input and output sensors. So I think the 98-01 use two speed sensors while 97-down use only the output sensor.

You weren't the only one I was doing all the info on the fly.

Yes the 98-01 use two speed sensors, one input and one output that 87-97 didn't have. Putting a 98-01 in an older XJ isn't a problem since you just don't use the extra sensor but is a problem going the other way.

 

[Evan463]

So NSS came off in about 18 to 20 pieces, still have one piece stuck on the shaft. ordered a new one yesterday. once that comes in i guess ill see where im at.

 

[lawsoncl]

You weren't the only one I was doing all the info on the fly.

Yes the 98-01 use two speed sensors, one input and one output that 87-97 didn't have. Putting a 98-01 in an older XJ isn't a problem since you just don't use the extra sensor but is a problem going the other way.

Going 98-01 AW4 into an older setup is doable, provided you swap over the rear sensor and rotor. The newer AW4 put out 4 pulse per rev versus 1 pulse/rev on the older ones. I made that mistake what I did my swap, and wondered why it was in 4th gear by the time I hit the end of the driveway.

 

[kastein]

Going 98-01 AW4 into an older setup is doable, provided you swap over the rear sensor and rotor. The newer AW4 put out 4 pulse per rev versus 1 pulse/rev on the older ones. I made that mistake what I did my swap, and wondered why it was in 4th gear by the time I hit the end of the driveway.

Speaking of this - I went to swap the rotors+sensors on my new AW4 last night and came to an interesting conclusion... the rotor is thicker on the newer transmissions and the old one will slide up and down on the shaft. Also, the newer sensor is a larger diameter mounting hole so you have to swap the tailhousings as well as the sensor. And last of all, I hate those snaprings they use with the slanted ends instead of actual snapring ends... I put it back together the way it was, I'm going to just build the circuit you designed. I plan to whip up a PCB design for it over lunch today, mind if I publish it for free download/use? Full credit will be given of course.

 

[lawsoncl]

I plan to whip up a PCB design for it over lunch today, mind if I publish it for free download/use? Full credit will be given of course.

Publish away sir!

 

[Evan463]

I believe the sensor change was in 97. More than likely the only difference is shift points or other minor programming changes. If you have a meter, then you can check quite a bit at the TCU connector. http://www.transonline.com/transdigest/magazines/1997-10/Shift Pointers/index.html for some info there.

If you suspect a bad NSS (and the no-crank definitely points in that direction), then it can be cleaned. Checkout http://www.go.jeep-xj.info/HowtoNSSrebuild.htm or http://jeepin.com/features/nss/index.asp. If you break it getting it off, http://www.teamgrandwagoneer.com/cgi-bin/partsSQL/search.cgi?query=neutral has replacements for $149.

So I bought a NSS from teamgrandwagoneer.com took it out of the box and one of the I guess you could call them tabs? broke off in my hands... anyone ever have any problems with any of there stuff? Calling tomorrow to try to return or get another one or see what they can do for me.

 

[MJR]

Going 98-01 AW4 into an older setup is doable, provided you swap over the rear sensor and rotor. The newer AW4 put out 4 pulse per rev versus 1 pulse/rev on the older ones. I made that mistake what I did my swap, and wondered why it was in 4th gear by the time I hit the end of the driveway.

Correct.

I believe the sensor change was in 97.

Incorrect. In 1998 the AW4 went to two speed sensors.

 

[kastein]

just FYI, rockauto has aftermarket replacements for about 40 dollars less than that. Not sure on quality yet. I've also heard Crown has replacements but don't know the price yet.

 

[lawsoncl]

just FYI, rockauto has aftermarket replacements for about 40 dollars less than that. Not sure on quality yet. I've also heard Crown has replacements but don't know the price yet.

Wow. I just looked and they do indeed have the 1987-1996 replacement on closeout for $107. Listing says there are two left. I don't know anything about kemparts brand though

 

[kastein]

Yeah, I'm tempted to pick one up. Not sure if I'm going to do that or simply hack up a magnet+reed switch or optical interruptor setup. I blew up the NSS on my spare spare transmission trying to remove it (damn whoever thought a split thread with a brass nut on a CAST ALUMINUM part was a good idea) and sorta object to paying $100-400 for what amounts to a special rotary switch on moral grounds alone.

 

[merkelb]

I'm super glad to have found this thread. I've been having symptoms exactly in line with what's been described. First, I was having intermittant reverse lights, then my jeep would have trouble down shifting after coming to a stop. Now my jeep never automatically down shifts unless I do it manually. Just the other day, I was having problems getting my jeep to start. After moving the shifter back a forth a few times, it would start. These are all indicators that the NSS is gummed up and causing the problems.

My "check engine" light is on and I haven't had it scanned. Could a fualty NSS cause this light to come on? Do I need to do anything to reset it after I repair the NSS?

I'm going to take a stab at cleaning out my NSS this weekend and will post my results. I've checked all my fuses and they are good so if this doesn't work, I'll start looking at the TCU and solenoids, but I'm almost certain the NSS is the problem. Hopefully I can get it off without breaking it...

 

[MJR]

Yes it can cause a check engine light on later models. Battery disconnect after to reset the light.

 

[lawsoncl]

My "check engine" light is on and I haven't had it scanned. Could a fualty NSS cause this light to come on? Do I need to do anything to reset it after I repair the NSS?

Yes it can. I'm will to bet the check engine codes will tell you everything you need to know.

Now the not downshifting is probably not the NSS. Is it trying to start in 4th from a stop? Have a look at http://www.transonline.com/transdigest/magazines/1997-10/Shift Pointers/index.html for some diagnostics you can do with a meter.