• NAXJA is having its 18th annual March Membership Drive!!!
    Everyone who joins or renews during March will be entered into a drawing!
    More Information - Join/Renew
  • Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

Another AW4 Problem

t-frady

NAXJA Forum User
Location
Bessemer City NC
Okay to start its a 96 country model 4.0 AW4
I just got it like 3 weeks ago so don't know alot about it yet
after looking for over 3 hours no symptoms match mine
First off I can not find a tranny fuse any where and just a few minutes ago found a pic of what the TCU looks like so I will try to unplug it tomorrow to see how it drives


While driving in D is starts off fine then immediately jumps to either 3 or 4 but not every time It will get stuck in gear such as while in 3 (while its acting up) trying to get it to shift normal it will be running around 2200 RPM and I will give it some throttle to speed up and it will accelerate then it feels like the torque converter unlocks I will let off throttle because it jumps to rev-limiter and then it goes back to 3

sometimes in D it will red line first then go to 2 and get stuck there redline or shift

Any ideas???
Tomorrow when I get home I will unplug TCU and try manually to see if it still acts up I know I will only have 1, 3, 4


Also under dash about center on drivers side there is a little silver canister about the size of a half a roll of dimes and it is super hot it has a yellow a yellow with red stripe and a pink wire what is this????

Sorry for the long read
Please help
Thanks Travis
 
What color is the fluid, does it smell burnt? Even if you arent too familiar with what ATF ought to smell/look like, you would know if it smelt burnt. and itll be brown in color instead of red.
The TPS (throttle position sensor) can affect transmission performance.
Mine got wet once and the tranny wouldnt shift out of first. Just a thought.

Along those lines, i can only assume (because you didn't say) that you checked the fluid level?
 
Test the TPS.

Cheap TPS from the big brand name auto parts stores are often out of specification or even defective right out of the box. You should always buy a JEEP or NAPA TPS. Cheap "Lifetime Warranty" parts are cheap for a reason.


You may have one or more of these Physical Symptoms:

1) The engine loses power and is stalling.
2) The engine will idle, but may die as soon as you press the gas pedal. When driving, it seems as if all power is gone.
3) Sometimes it feels as if the transmission is failed or isn't shifting properly, if at all. If you quickly jump on the gas you might be able to get the transmission to shift, but it won’t shift properly by itself. Shifting manually, the transmission goes through all the gears.

NOTE: The throttle position sensor is also DIRECTLY involved with transmission shifting characteristics. The TPS function should be verified early in the troubleshooting process, when a transmission issue is suspected.

TPS TEST

You should have 5 volts going into the Throttle Position Sensor (TPS). It is best to use an analog meter (not digital) to see if the transition from idle to WOT is smooth with no dead spots. With your meter set for volts, put the black probe on a good ground like your negative battery terminal. With the key on, engine not running, test with the red probe of your meter (install a paper clip into the back of the plug of the TPS) to see which wire has the 5 volts. At idle, TPS output voltage should be greater than .26 volts but less than .95 volts. Move the throttle and look for smooth meter response up to the 4.49 at WOT. The other wire will be the ground and should show no voltage.

Perform the test procedure again and wiggle and/or tap on the TPS while you watch the meter. If you notice any flat spots or abrupt changes in the meter readings, replace the TPS.


The TPS is sensitive to heat, moisture, and vibration, leading to the failure of some units. The sensor is a sealed unit and cannot be repaired only replaced. A TPS may fail gradually leading to a number of symptoms which can include one or more of the following:

-Poor idle control: The TPS is used by the ECU to determine if the throttle is closed and the car should be using the Idle Air Control Valve exclusively for idle control. A fault TPS sensor can confuse the ECU causing the idle to be erratic or "hunting".

- High Idle Speed: The TPS may report faulty values causing the engine idle speed to be increased above normal. This is normally found in conjunction with a slow engine return to idle speed symptom.

-Slow engine return to idle: A failing TPS can report the minimum throttle position values incorrectly which can stop the engine entering idle mode when the throttle is closed. Normally when the throttle is closed the engine fuel injectors will be deactivated until a defined engine RPM speed is reached and the engine brought smoothly to idle speed. When failing a TPS will not report the throttle closed and fueling will continue causing the engine to return to idle very slowly.

-Engine Hesitation on Throttle Application: The TPS is also used by the ECU to determine if the driver has applied the throttle quicker than the Manifold Air Pressure sensor can read. The fueling is adjusted accordingly to cope with the sudden increase in air volume, however a faulty sensor can cause the ECU to ignore this data and the engine will "hesitate" when applying the throttle. In extreme cases with the engine at idle, a sudden application of full throttle can stall the engine.

- Engine Misfire: A faulty TPS can report values outside the acceptable range causing the ECU to incorrectly fuel the engine. This is noticeable as a slight misfire and can trigger the misfire detection software and/or Malfunction Indicator Lamp (MIL) light on the dashboard. Extreme cases can cause excessive misfires resulting in one or more cylinders being shut down to prevent engine and catalytic converter damage.
 
The little guy under the dash that gets as hot as Hades is the ballast for the illuminated ring around the key. If the door's open long enough for you to get into position to feel the heat, it has heated up enough to feel hot.

As far as the tranny acting up, it sound suspiciously like how mine acted when the Throttle Position Sensor-TPS-was acting up. Erratic shifting, TC locking and un-locking randomly, unintended acceleration at inopportune moments. I bought a new (better of the two offered) Standard brand, and it was worse than what it replaced! I went to the JY, stocked up on a few of the lowest-mileage examples I could find, and got a winner. The TPS are the same (auto trans, of course) from '91 to '96. The plug changed near the end of '96 model year (Classics?), so watch out for that.

My '96 behaved fine until I took it in for the recall to 're-flash' the computer. After that, in the past two years, I've been through five TPSs, and the dealer that performed the recall doesn't know what was involved, nor do they want to deal with any of my complaints about what may have happened due to the recall. See if yours has the sticker on the radiator support, and if it hasn't been done, I wouldn't recommend it.
 
Tim-That is an excellent write-up! It appeared when I posted my reply. I wish I'd had this over the last two years, as it would have saved a lot of time just checking resistance with my digital VOM. I used the TPS in my '92 (a known good piece) to get resistance values, and checked my half dozen junkyard candidates to find one that was the closest in readings. I found one real close, and it's still in my '96, behaving beautifully! Hope I didn't just jinx myself! I'm printing your post and putting it with my service manuals...Thanks!
 
thanks alot guys about to head to napa to buy a tps and give it a shot



BTW I can't see the TCU under dash which side is it on I thought it was on the Drivers side under dash?Do i have to take dash apart to see it or what? it is silver and the size of 2 packs or cards is this right???
Thanks again
 
Tim-That is an excellent write-up! I'm printing your post and putting it with my service manuals...Thanks!

X2 Thanks
 
I had a $20 card to autozone so thats where I got it and It didn't fix the prob My buddy has one in his 96 5spd I will try his to see if it fixes the problem all you have to do is install it then unhook the - battery cable is this right???
 
okay replaced TPS with buddy's and still same prob so I got a TCU from junkyard from a 96 and another from a 91 both were free so why not

With my original TCU unplugged it will shift just fine manually 1 3 and 4 will update again soon
 
I fought my AW4 for two years chasing problems. Replacing the TPS many times. I pulled the solenoids out of the transmission and tested. Cut out all of the connecting plugs and hard wired them. Then one day I got fed up and when it started acting up I leaned over and snacked the dash on the bottom of the passengers side where the computer is really hard and FIXED. A few weeks later it started acting up again and a good smack and then it would shift. so I took the computer loose and pushed and pulled the connector on and off like sixty times and it hasn't acted up for close to year now.
 
which computer are you referring to????
It seemed like today when I installed a different TCU it downshifted one time when I first took off but then quickly jumped to 4th gear again

So what else could this be
Would a dirty tranny filter be the case??? I have a new one but not installed yet
Just a thought I just installed the axles off my other jeep which are geared 4.88 would this be making the computer think it should be in OD because my speedo is off?????
I didn't drive it but one time on the 33's that came on jeep with stock gears but it ran fine. But then on another note it seemed to run fine with the 35's the first couple days

Even with the other TCU installed it still skips straight to 4th from 1st in D and if in 3 it skips from 1st to 3rd and will NOT downshift in either gear
 
Have you looked at the NSS? I think that too affects the shift pattern. Also if youhave not done so test the solonoids in the AW4. There is a write up here on how to test them usine an OHM meter.

Years ago when the AW4 in my '96 was not shifting properly, the two solonoids for the gears tested bad. Like yours, it mostly try to move from a stop in high gear. Stepping on the gas pedal would only cause it slip more. Manually shifting it always worked (but it negated the reason for having an automatic). I replaced all three and have not had problem since.
 
I'd adjust the TV cable, then do a ohm test for the number *1* solenoid and number two at the TCU connector. There may be some resistance at a connector, harness or maybe a low or high resistance at the solenoid.
I have a low resistance condition in my number 1 solenoid now in my 96. I figure the coil in the solenoid has jumped continuity (the resistance is low) on a couple of windings, it likely overheated at some time.. One of those things that is on my list of things to do, it isn't really broke yet, but getting flaky.
Also check out the TCU connector well, I've seen a number of loose pins and partially backed out pins in the TCU connectors. I make sure the pins are seated all the way in, push the wire into the connector (moderately hard) and then pull a little to make sure the little lock tab on the connector pin/contact is working. Clean the connector with a quality contact spray, these are formulated to remove corrosion.
Checking connectors underneath is always a good idea, they may be oil soaked and are often the first to corrode.
Check the TPS connector, better than fifty percent of the time it is a continuity problem and not a sensor problem (on any sensor). 0.1 volts-5.0 volts isn't much voltage and it doesn't take much much oxidation on the connector pins to affect it. I most always check the wiring and connectors before I buy the sensor or component, I buy very few sensors or components.
 
Last edited:
the tv cable was adjusted when the TPS was replaced the first time Ill look up about testing solenoid

But really the NSS could be it too???
Is there nothing on a jeep that don't control the shifting LOL

Someone told me today it could be the speed sensor on the tranny NOT the one for the speedo that is on the T-case
 
Someone told me today it could be the speed sensor on the tranny NOT the one for the speedo that is on the T-case


The 1996, well at least my 1996 have only one speed sensor which is in the T-case.

The symptoms you described seem to indicate a problem else where in the system other than the speed sensor but I would not entirely rule it out. Take a look at the speedo and try to guess wether or not the indicated speed is close to what you think is the real speed. (A GPS would be useful for this test.) A speed sensor that indicates a speed higher that the vehicle is actually traveling will cause the AW4 to upshift sooner. However, you should be able to use the pedal to force a down shift.

Have you tried to manually shift it via the pedal?
 
Yea it will not downshift
I didn't think the speed sensor on t-case would be it
but I need a 39 tooth its got the stock one in it but I did find a 40 tooth at the local pull a part which would put me a lot closer to normal.
 
Fixed Had 2 bad Solenoids tested using the D7 is neg. and C14, C15 and C16 method
 
Fixed Had 2 bad Solenoids tested using the D7 is neg. and C14, C15 and C16 method


It is a nice feeling when the gremlins are finally evicted.
 
Back
Top