4-speed auto question

I have a problem with my trans not kicking down into 1stwhen I come to a stop. If I manually shift down it goes into it and once I get up to about 25mph I can shit into od and it will shift through the gears properly. the obd2 doesn't pick up any problems and I thought I would just get it rebuilt but the two tranny shops I have talked to doesn't belive that is internally in the transmission but a sensor but I cant figure what sensor could cause htis problem anyone else have this problem if so what was your fix

How's the tranny fluid level? Is it clean?

pancake

the fluid is clean and full I bought this XJ in late 97 this is the first real problem I have had I pulled the newbie error though I asked before I searched. through my search I think it has all the indications that it is the TCM what I really would like is the trouble shooting steps for the AW4 TCU

I cleaned plug at tcu

I cleaned the plug the yellow wire with black trace was green and croded cleaned it pulled the connection from the plug cleaned it thought I had it fixed seeing a obviouse green gummed up plug unhooked the batery hooked back up took it for a ride problem still exsists. could it be the throtle position sensor/ where is it and how do I check if it is working. secondly is there a way to check if tcu is working or not.

Try adjusting the TV cable. Mine was shifting wierd after installing a TB spacer, so I adjusted this cable like I do for a chevy 700R4 tranny, and it shifted normal again. On the housing lock for the cable near your TB, the is a release you can push to unlock the cable housing. Push this "button" and hold it while you open your throttle all the way. Engine off of course. This should take out all the slack in the housing and allow the tranny shift according to throttle position.

I'm not sure if this is any standard jeep procedure, but it seemed to work for me.

Any of you guys that know for sure, let me know if I started the self destruct sequence.......

HTH, Dan

Tightened the TV cable what next

I thightened the tv cable and that didn't make a difference anither symptom is there is a rattleing in the tourque converter almost like the it loose but the bolts are all tight could it be stuck in lock if so how do I check or fix other then repace the tourque converter.

I rechecked all the fuses under the hood

I rechecked all the fuses under the hood all are good I drove with the tcu un hooked and when in 1-2 it wouldn't shift from 1 to 2, when tcu hooked up it will I am wits end. I have had problems with the park brake switch on the side of the tranny before cuasing it not to start and it was in preaty bad shape could this be causing it? also all the info for testing the tps has been for the older renix units mine has two three wire plugs which ones do I test please help

By disconnecting the TCU it will not shift into second gear. That is part of the diagnostics checks described in the FSM for the tranny. It says to pull the TCU fuse though, but I'd imagine it would do the same thing. To me the automatic trannies work by magic, but I remember reading for sure about pulling the fuse to keep it in first.

Don't know what to tell you. Hope you get it figured out.

Dan

Dude, the problem is obvious - you ain't got no periods, your jeep ain't got no periods. You sentences run together so we can't understand you, and therefore your jeep can't recognize when you stop at stop signs. It makes perfect sense, cause and effect. Get some periods, and learn how to use them! That'll fix your jeep, just try it and see.

Okay, just ribbing you there. On your prob, you say 1st works okay if you're running but not starting out, is that right? I wasn't sure what you meant about all gears work over 25, 1st is already gone by 25 unless you're accelerating hard. And you say first works if you put the shifter in 1-2 - does it shift to 2 when it's supposed to with the shifter there? And it makes no difference what you do with the throttle, like if you push it too the floor or just go at idle? Give us a better description on all this if you will.

Dan, about the TV adjustment, that is most definitely a jeep procedure and is in the manuals, and it's a necessary one too at least for me. My tranny gets out of whack about every 10k and shifts all funky - sometimes it downshifts on its own and revs while I'm stopped at a light, sometimes it won't shift until way past the normal RPM point. Then I do the TV adjustment and it shifts perfect. The first time this happened after I bought it, it about drove me crazy trying to find the problem before I finally tried the TV adjustment. It really sounds partly a lot like barney's problem.

Barney, if you're sure you've done the TV adj right, and you're sure your fluid is full and in good condition, and you try my idea about using periods in your posts and it still won't shift right, then you might try PM'ing Beezil - he's a AW-4 expert I think. Look over on that monster 20 page thread on the Mod board, I know he posted on that several times, and click the PM button next tohis user name.

92XJSP

Sorry about the run on sentenses I Surf at work and try to fly below the nazi IT guys radar if know what I mean. O.K. about your question yes, it shifts from first to second no matter how I accelerate when my shifter is in the 1:2 position. I adjusted the TV cable just how it was described here and on several other posts that I searched out. adjusting this did nothing in solveing the problem. I have had a problem with my shifter position switch on the side of the tranny it is preatty broke up. I smashed it in moab everything seemed to work fine after I epoxyed it back together. But since it is some what broke I was wondering if this could be the cause of my problem. I am at wits end with this thing at work tommorow I will PM thanks to all, all help is greatly appritiated. P.S. does anyone have the wire diagram for a 96 cherokee.

Barney, the two main sensors that determine the AW-4 shifting are the TPS and the OSS (output speed sensor). I would check the TPS first. One plug goes to the TCM and the other to the ECM. It dosen't matter which one you test, they both should show the same signals. TPS's DO wear out, so that may be your problem. Look for a smooth transition from about 1v to 4v on the signal wire, as the throttle is advanced.

The OSS is located on the transmission tailshaft, and it gives the TCM vehicle speed info. You could probably hook a voltmeter to it, and spin a rear tire manually to test it. There should be a small voltage pulse (less than 1v) as the driveshaft turns.

Why don't you crawl under it and take a look at the OSS? Maybe it's as simple as the plug being knocked loose from the sensor.....

thankyou running on empty

Ill check both of those today with luck Ill find a problem. I have read through searches that there is a adjustment to the TPS. Is this true or is this just on the older renix units

I checked the TPS and speed Sensor both checked good

OK now what to check I have checked these two and both checked good anymore Ideas would be greatly appriciated.

Thought I´d throw my two cents in. Just something to check, might be related might not.
Take it up to cruising speed and touch your brakes lightly, does the torque converter unlock?
On one of my projects gone wrong (in a Chevy, not a Jeep), I tried to wire a relay into my brake light switch, wired it into my converter release switch by mistake, tranny really argued with me, about going into low gear.

any thought on setting the TPS ... 'wrong' output there coud indicate that you're still on the throttle but the "zero" from the tailshaft output (not the speedo for folks that are confused, the AW4 watches itself) should allow Solinoid #2 tod drop out ...

interesting though - s2 also drops for 4th gear -- you should really be able to tell the shift, then the TC lock-up...

That TC lock check (light foot on brake while rolling while watching the tach for the unlock) sounds like a good thing at this point...

I love jeeps thread may have some additional diagnostics for ya...

just fer giggles, check to make sure you don't have a leaky rear cylinder....you mentioned you had a problem with heat. if you sense any lugging, or that "bowling ball in the trunk", It wouold be something to check, although it sounds like you have one or two things that point to something else.

Hey, one other thought diagnostics-wise. You say it doesn't downshift when you come to a stop. What about if you're moving in second gear and then gradually slow down to the point where it needs to go into first, does it just lug along in second and still never downshift? If so, does it do the same in 1-2 as is drive? And does it do this also in 4-lo as in 2-hi?

It just seems strange to me that it will function correctly with the shifter in 1-2 but not in D, which makes me doubt that it's the TPS or other sensors. Wiring seems a possiblity, especially since you say the shifter housing is a bit mangled. Possibly with the selector in D something is making contact and shorting which doesn't happen with the shifter in a different position.

Beezil

on rear cylinder you are meaning a brake cylinder not something else right. if so no rear break cyliders look good.

.... 92xjsp

sorry I started a new thread with your reply I wont let it happen again sorry. also I forgot to mention that when cruising at 50 55MPH if I tap the brake the torque conveter unlocks I can hear the RPM's of the motor rev up for a split second. is there any kind of sensor inside the bell housing.

barneycj-8
Jeeper

Registered: Nov 2003
Location: Orem, UT
Posts: 13
92xjsp
When I gradually slow down to a stop, and the shifter is in position 3 or OD it will not shift all the way down to first. It does however shift down to all the othe gears IE OD to third then down to second. It will also shift down into passing grear under hard acceleration. I havent tried it in 4-lo I will when I get off of work. As far as the TPS I checked the voltage at the TPS unit also where those wires feed into the TCU. At both locations with throtle closed it reads .75 volts gradully incrases as throtle is increased. Only funny thin is at full throtle the fluke reads Over load, but that is only at full open I'm not sure if it the meter or TPS. Could this be my problem I am going to try the reading with another meter tomorrow.
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Barney, okay, so with the shifter in D it downshifts everywhere except to first - now try it with the shifter set at the 1-2 spot. I mentioned doing the same comparison in 4-lo because for most XJs the shifting action is more pronounced in 4-lo than it feels on the road and so might be easier to trigger, but you should get the same answer both ways.

What I was trying to go after was to see if everything really was okay with the shifter in that 1-2 position - you say it will start out in first that way, but the big question is will it downshift to first. I'm guessing it won't, that you won't get a downshift to first even in 1-2, and in that case that would seem to narrow the problem down to replacing whatever sensor is responsible for judging when RPMs get so low it needs to sift into first gear. But is that sensor the TPS? Doesn't seem like it, since throttle position doesn't correspond to engine RPM directly - if you're going downhill with little throttle it won't need to downshift, but if you hit a level spot with that same throttle position, it's going to need to downshift. So there has to be another sensor, seems like, unless the TPS also watches RPM. ROE mentioned the OSS, output speed sensor, and satan mentions that a tailshaft output sensor, which sounds like the same thing. I had not heard of that sensor before (and I don't see it in my FSM) but that does sound like what I'm looking for here.

This is getting out of my knowledge range, and I'm only speculating here because you haven't gotten an answer from someone more knowledgeable. Hopefully somebody will bail me out soon by explaining how it decides it needs to downshift to first when RPMs go way down - is it the tailshaft output speed sensor, and is this something barney can easily take out and replace? Or does the TPS watch revs, too? I know that's just a $30 part and is easy to replace.

BTW, I don't see this condition in my FSM in the tranny troubleshooting table. There's an entry for "no low gear, only moves in 2nd-3rd" but you have one when you shift to 1-2. Anyhow, if you're interested, what it says about "no low gear" is
1. governor valve sticking in partially open position
2. valve body malfunction
3. front servo piston cocked in bore
4. front band linkage malfunction
(all which translate, for me anyway, into the same thing - mucho $$$ at tranny shop - hope it's not that.)