b_heier.4X4

So here's my problem. My 1996 Cherokee sports transmission is being a problem. When I come to a complete stop say at a stop sign or stop light it doesn't shift down into first it stays stuck in third gear...so when I give it gas to go it takes a long time to get to the speed I want and uses more gas than needed, also when I go to pass someone or I need to gain some speed I doesn't down shift it just slowly accelerates. I took it to a mechanic and they can't figure out what is causing it. Any and all help is appreciated!!

b_heier.4X4

anyone?

tjwalker

Throttle position is a primary suspect. Input signals from the TPS directly affect the AW4 transmission performance. Here is more....
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The throttle position sensor is connected to the throttle shaft on the throttle body. It sends throttle valve angle information to the PCM. The PCM uses this information to determine how much fuel the engine needs. The TPS is really just a simple potentiometer with one end connected to 5 volts from the PCM and the other to ground. A third wire is connected to the PCM. As you move the accelerator pedal with your foot, the output of the TPS changes. At a closed throttle position, the output of the TPS is low, about a half a volt. As the throttle valve opens, the output increases so that, at wide open throttle, the output voltage should be above 3.9 volts. Testing can be performed with an electrical meter. Analog meter is best. You are looking for a smooth sweep of voltage throughout the entire throttle band. While slowly opening and closing the throttle, take note to the movement of the voltmeter needle. There should be a direct relationship between the needle motion to the motion of the throttle. If at anytime the needle moves abruptly or inconsistently with the movement of the throttle, the TPS is bad

You should have 5 volts going into the TPS. At idle, TPS output voltage must be greater than 200 millivolts. At wide open throttle (WOT), TPS output voltage must be less than 4.8 volts.. The best is 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. One of the other wires should show .26V (or so). The other wire will be the ground and should show no voltage. Move the throttle and look for smooth meter response up to the 4.49 at WOT.

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: -

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

• 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 acordingly 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 fault TPS can report values outside the deined acceptable range causing the ECU to incorrectly fuel the engine. This is noticable 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 excessing misfires resulting in one or more cylinders being shut down to prevent engine and catalytic converter damage.

excess650

Yours is doing what mine does and I haven't sorted it out yet. I've checked the voltages to/from the TPS and swapped it out anyway. I swapped out the TCU and it didn't make any difference. I've since swapped out the VSS and it still didn't make any difference.

My trans shifts fine manually, as in with the TCU disconnected. 1-2 will get you 1st only, 3 will get you 3 only, and D will get you OD only.

With the TCU connected it will sometimes shift up/down properly, but never selects 1st when stopped. I've seen it go into OD at 35mph which made me suspect the VSS.

I'm now thinking that I have a bad ground or other broken wire somewhere...its not my daily driver and I onlu have so much time to mess with it!

PLEASE post your findings.

You DID check ALL of the fuses, correct? There are fuses in the panel above the driver's feet and another panel under the hood on the passenger side inner fender.

freegdr

have you ever adjusted the kickdown cables

b_heier.4X4

I have adjusted my kickdown cable...but I haven't looked into the tps and will do so this weekend. This is my daily driver so the sooner the better!

excess650

My problem started like yours and got worse over time. I found that I could manually pull it down to 1-2 to pull out and upshift to 3 at 2500rpm or so. It wasn't my daily driver, so I wasn't terribly concerned....as of late I'm wanting it to work correctly and have asked questions here, searched here and other forums, and think I have found my problem.

There are a pair of connectors near the trans dipstick. The black 8 pin goes to the NSS. Just for giggles, unplug it and verify that you have continuity where you should in P-R-N-D-3-1/2. Unplug the grey 7 pin and check the female side. The center pin of the row of 3 is the ground to the trans. Check for resistance/continuity to the ground post of your battery. You'll want to see less than 1 ohm, and the reading should be closer to what you see when you touch your VOM leads together, say maybe .3 ohm. If that proves out, your ground is good, and you'll need to check the solenoids. The other row has 4 pins. The pin offset and the 2 closest to it in the same row are the solenoids. When checked to ground they should show 12-18 ohms. I suspect your #1 solenoid is failing or has failed. Mine has and shows 18K ohms!

b_heier.4X4

I actually have had my #1 solenoid replaced less than a month ago. Which helped some rough shifting I had but nothing else.

excess650

....so lets start at the beginning....what symptoms do you have? Will it select 1st when you try to pull out in D or 3? Does it downshift properly from D to 3 and 2?

b_heier.4X4

Doesn't always shift into first when I come to a complete stop and sometimes doesn't downshift when I pass people. The only time it shifts 100% right is when I manually shift. Then the second I put I in D it starts to mess up again.

excess650

Yours is doing what mine did when I first noticed a problem. It would occasionally not downshift to 1 when stopped at a light or stop sign. Over time it got worse so that it would never select 1st when put into D or 3, and wouldn't downshift from 3-2 in a passing situation. It DID shift from OD to 3.

The items in play are the TPS, VSS, TCU, TCU fuse, and brake switch. The other thing to check is the kickdown cable. The brake switch unlocks the TC. IF the fuse for the TCU is intact, mine is a 10a in the fuse box on the passenger side inner fender, the TCU should have power.

The TCU should send voltage to the solenoids depending upon inputs from the TPS and VSS.

You say it shifts manually. With the fuse out or TCU unplugged, you should get 1st when selecting 1-2, 3 when slecting 3, and OD when selecting D. Is that what you observe?

With the TCU and fuse in place, selecting D should get 1-2-3-4. 3 should get 1-2-3. 1-2 should get 1 and 2.

If the 1-2 shift solenoid isn't working, you should still be able to get 2nd by placing the trans in 1-2 and running the revs up to 4500rpm. Line pressure should force it to shift, and if you back off the throttle, it should downshift to 1 as the pressure drops. This IS what mine is doing. The 1-2 shift solenoid must be good for the trans to select 1st when in D or 3, and must also work to electronically shift 1-2 or 3-2.

You say that you've had the solenoid replaced recently. Have you checked the solenoids for resistance with a VOM? Pull the grey 7 pin connector apart (near the trans dipstick). The row of 4 pins on the female connector is where the wires to the (3) solenids reside. Put one meter lead on the ground post of your battery, and touch the other end to each of those pins. If the solenoids are good, they should show 12-18 ohms resistance. If they show more resistance, or none at all, you either have bad wiring or solenoid(s). Wt/Bk is S3, Vt/Wt is S2, and DB/Wt is S1. S1 and S2 are the shift solenoids and S3 is the lockup solenoid.

The center pin of the row of 3 on the male connector should show continuity to the battery ground as it is the ground from the TCU to the trans.

PM me your email address and I'll reply with an attached 3.1mb file that is the Chrysler troubleshooting manual for the AW4. It has pinouts and flowcharts that I've not found elsewhere. Its pretty easy to follow.

b_heier.4X4

Thanks hopefully this manual helps!

excess650

I ordered a shift solenoind late Monday, and picked it up Wednesday. It FINALLY quit raining long enough for me to install the solenoid, reinstall the pan, refill with fluid, and take a test drive. I did this in my driveway....
It seems to shift as well as it ever did, and I've noticed that some of the oddities that occurred have also been resolved. It didn't seem to shift quite right 3-OD or OD-3 prior to changing the S1 solenoid, and I think it was a function of lack of lockup as much as anything. There isn't a problem now, but its definitely working differently, and for the better.

b_heier.4X4

awesome
ive been slowly making my way to testing the sensors. i had to finish my exhaust which i just got and i had to replace my downstream 02 sensor that snapped in half.
but i did test the tps and everything seemed fine.but the trans is getting worse...so i figure just take it to a transmission shop have them tell me whats wrong and then ill fix it myself.

89cher40

between the info on this forum and another xj forum i started the testing for the tcu under the dash. first unplugged it ,checked the fuse just before the tcu and it was good so i checked for batery voltage at two different places on the plug (that the directions called for). at first i didnt get voltage at one of the female term that i was supposed to. then i checked it again a few minutes later and i had the rite voltage.directions said to test drive and see if it still the same.it must have been a bad conn because it runs like a new jeep everything shifts like it should. is all i did was unplug and plug back in the tcu to fix (lucky day i guess ) if any body wants this info i will post later. not sure how to post that yet. good luck