...must be aw4 night

[frankv569]

i ve been reading up on old questions and cannot seem to find exactly what i am searching for. the tranny on my 96 xj (aw4) seems to be goofing up.if i am driving along at about 45 mph or so, with the shifter in the o/d position and press in the gas to where you would think it should downshift to second and start to accelerate, it almost seems to upshift and bog down unless you floor it or manually downshift. im not sure if it is really upshifting - but it sure seems like it. also, i have been noticing that when im commuting on the highway (75 or so mph) on level ground , I can notice the tach keep raising 200-300 rpms or so and you can hear the rpms increase out of the blue with no load or throttle position change. i could understand it its the t/c unlocking and going 'down' into regular overdrive - but why if the load hasnt changed nor the speed? seems odd to me. it seems to be acting up like this more frequently. i have 30x950's and 3.55's. i changed the fluid out about 2-3 months ago with advanced auto parts brand of dex3 / merc fluid. is this fluid acceptable? is this an early warning of failure? what to do?? what to do?? it does seem to not act up as much in the regular drive position.

 

[MJR]

Sounds like something similiar to mine when the TCU fuse was blown. A bad TPS could cause problems. The brake switch can cause the torque convertor to lock/unlock.

 

[frankv569]

how would i check for a tps problem? where is the fuse located and what might make it blow?

 

[MJR]

Don't know why it would blow (short) but look in the owners manual for the fuses and locations. You could unplug it and check the resistance with a multimeter. You just want to see if the resistance changes smoothly when the throttle is opened and doesn't jump in readings (bad spots)

 

[Dragon_Fly]

I know mine is a much older model.. I have an 88 with the AW4. I washed my wagon and started having the issues as you. I tested the TPS and it was good. It was adjusted properly. CPS tested good. MAP tested good. It wasnt until I pulled the main cable bus located above the brake booster that I found the problem. It was nasty with corrosion. I cleaned all the contacts and loaded it with dielectric grease before bolting it back together. Seems to work fine now. Not sure if this will work for your jeep but it did for mine.

 

[MJR]

I know mine is a much older model.. I have an 88 with the AW4. I washed my wagon and started having the issues as you. I tested the TPS and it was good. It was adjusted properly. CPS tested good. MAP tested good. It wasnt until I pulled the main cable bus located above the brake booster that I found the problem. It was nasty with corrosion. I cleaned all the contacts and loaded it with dielectric grease before bolting it back together. Seems to work fine now. Not sure if this will work for your jeep but it did for mine.

The C101 connector was on 87-88 models and caused problems with TPS ans CPS. 89-90 eliminated it and a replacement harness comes without it. I cut mine out and soldered the wires because of it.

 

[Atl XJ]

You try indexing the kickdown cable? Or do 96's still have one? My 95 does and it was doing that and it solved my problem. HTH

 

[MJR]

You try indexing the kickdown cable? Or do 96's still have one? My 95 does and it was doing that and it solved my problem. HTH

It's not a kickdown cable. It's a line pressure cable. It controls line pressure during shifts.

 

[frankv569]

i appreciate the quick responses! i will try to find out as much as i can about the tcu and see where it all leads. thanks!

 

[cjwalkeriii]

i had an 88 with a similar problem... got it wet and it went to hell. turned out to be the tps. i am here in pitt too, so if you need a hand let me know. did you say you tested your tps? let me know. i am up in mt washington. later

 

[frankv569]

ok ok im still confused!! as a n update, i took it to a tranny svc center and test drove it with them. it acted perfectly - i was mad ! i had them flush the tranny since it looke d pretty bad and i was gonna do it soon anyway (changed it like 6 thousand miles ago - looked pretty bad like reallly old fluid). they ran a scanner on it too and said all ok. the original problem was that when driving on the highway at about 70 mph, in drive or od , all of the sudden the torque convertor would unlock and stay unlocked. sometimes if i went to neutral and back in to drive or od, it would go back into lockup-sometimes not. i figured out the bogging down thing too. its related. if i am driving and it wont lockup, its runnin about 2500 rpm at 70 in od range. if i depress the gas to accel, you would think the rpms should increase since youre hitting the gas- well ,it does. it goes up to about 2700-2800 rpms for a second. then, it bogs right down to about 2200 rpm - its the rpm it should be at if at 70 mph when locked up. so, basically, if i am driving at 70mph down the highway, it unlocks the convertor out of the blue - no headwind, no hills , no throttle position change - just out of the blue. and, the only way to get it to lock back up is if i depress the gas a little - as if i were passing or trying to maintain speed on a hill. what the heck??????? i am losing my mind and i dont know if i can trust it ! help ! help ! help ! please!! lol

 

[UNCC_99XJ]

I have a question for the experts out there.....

Is there any way to control the OD on the AW4? I know it kicks in around 42mph depending on how much you have your foot into it, but I was just wondering. I love how it will just sit there and cruise in 4th all day long. Got almost all the passing power I need to get around anybody. I was just curious cause just about every automatic i've driven has the OD button on the shifter (or somewhere in the general area of the shifter). Is there a button or something i'm overlooking?

Frank, I forgot to ask ya, how much did it cost to get your tranny flushed and where did you go? I'm looking into doing that to mine soon, mainly cause the fluid is STARTING to look spent, and for peace of mind. Trying to get some estimates here as i'm on a very limited budget.

 

[MJR]

I have a question for the experts out there.....

Is there any way to control the OD on the AW4? I know it kicks in around 42mph depending on how much you have your foot into it, but I was just wondering. I love how it will just sit there and cruise in 4th all day long. Got almost all the passing power I need to get around anybody. I was just curious cause just about every automatic i've driven has the OD button on the shifter (or somewhere in the general area of the shifter). Is there a button or something i'm overlooking?

Just put the shifter in the 3 position.

 

[WobblesXJ]

Check the brake switch. Mine was bumping at odd times and eventually read closed which kept the torque converter from locking. I've heard of a few other people having problems with this switch too.

 

[Digger87xj]

Check the brake switch. Mine was bumping at odd times and eventually read closed which kept the torque converter from locking. I've heard of a few other people having problems with this switch too.

Bingo

It is located on a bracket above the stop lamp switch. If the xj has cruise, it will have a vacuum line attached to it also...

 

[frankv569]

well, i havent had a gauge on it to read continuity. but, when it is not acting up, i can lightly depress the brake with the gas applied still and it will lock up and unlock properly when i tap the brake pedal. it is intermittent - sometimes it acts just fine and other times, no lock up whatsoever. it is really pissing me off to all high hell! i also noticed that when i depress the throttle lightly as if i was starting up a grade and trying to maintain a given mph, or if i keep pressing in on the gas further and further, it never comes out of lock up and back down into overdrive - but, eventually, it will just kick down to third instead. very strange ! i just wish it would do what i am telling it to do! ! has anyone ever been accelerating at full throttle while locked in the 1-2 range manually and when you think its givin all it has, you manually upshift to drive or overdrive while still floored - engine rpm at about 4500, then it will start to accelerate faster and rpms raise a couple hundred rpm instantly and accelerates even faster? it does that too. just wondering if that is considered normal.

 

[frankv569]

i found an online manual that says if its not locking up in 2nd , 3rd, or 4th it could be because of an electronic control problem, a faulty valve body, a solenoid faulty, or a faulty tranny. would anyone know how to really check these out?? i had a tranny shop run a scan tool on it two weeks ago and they said no faults were found. is there a better way to check or does it need checked by a dealer? does anyone have any info at all??