xjfan0310

Alright so I have a 96 XJ with 160k on it and the aw4 tranny. The tranny slipped while driving 70 mph. Well it may not have slipped but it definitely down shifted for no reason from OD to 3rd. Driving it home I had 3rd gear and it wouldn't down shift to 2nd for about 15 miles. Then it started workin like normal. (July 8th)

So I checked the fluid. It was a little low. So I drained it (4qts) replaced the filter and topped off the fluid. Everything looked fine in the pan no chunks or debris. (July 10th)

It's been working fine for a week and a half. Until tonight on the way into work. I was going 55mph and it shifted from OD-3. then a few mile down the Rossi was going 30mph and it down shifted then upshifted.

Now about a month ago I put 31s on it before I had 30s. I don't know if this would effect anything or not. I'm a newb to lifting jeeps adding rubber and all that other stuff. There are no codes and no engine light. Fluid is red and full.

Is the VSS reading right?
Does the kickdown cable need to be adjusted? (where is it, I haven idea)
TPS bad?

Please help.

94JeepCherokeeMan

Do you have cruise control? If so, you'll have three cables going to your throttle body. If not, you'll have two. One is the accelerator, one is the tranny kickdown cable, and the third, if equipped, is the wus- ... I mean... Cruise. Control... The accelerator cable hooks on a ball joint end, but my cherokee is a five speed with no cruise, so I cant pinpoint the other two for you. Do some looky-looing and find out.

xjfan0310

Yep I've got cruise control. I had to take the throttle bracket off the intake (or whatever that is) to get the valve cover off to replace the valve cover gasket. Could that be my whole problem maybe that cable isn't where it was?

tjwalker

Adjust throttle cable and test your throttle position sensor. The throttle position sensor is DIRECTLY involved with shifting on the AW4.

Here is a link to the cable adjust and more on the TPS.
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http://naxja.org/forum/showthread.php?t=1015963
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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

First of all, are you confusing OD with lockup? Mine shifts 1-2 @20mph, 2-3 @30mph, 3-OD @ 40mph and goes into lockup at 45mph with a light, right foot. Shifts to 3rd and OD are fairly soft, but can be seen on the tach. Lockup feels like another shift and will drop the revs another 200-500rpm.

(1)Adjust the kickdown cable.
(2) Test the tps. My '96 showed 5.1v input, .76v output with the throttle closed and 3.8v with the throttle wide open.

The brake pedal switch affects lockup and will disengage it when the brake pedal is depressed.

The VSS is on the tailshaft of the trans, LH side and easily accessible. Check the plugs and wire as it sends signals to the TCU.

The NSS was the culprit in a recent thread about the lack of OD. It can be tested and cleaned.

PM me your email address for the AW4 manual and diagnosis manual.

xjfan0310

Excess- I already got the manuals from you the other day. I read thru them and it was like gibberish to me. The way you and person before explained it makes sense not the way the manual says it.

I may be talking about lockup..I was on the freewAy cruising at around 70-75 and all of a sudden the tach spiked at 3000 an it felt like the trans down shifted. I'm going to adjust the cable in a bit. I had the throttle bracket off the manifold when I was doing some work on it a month and a half ago. I think and hope it just needs to be adjusted bc it didn't do any of this before I had in the garage for a month working on it.

94JeepCherokeeMan

As for what you said earlier... If it wasn't shifting weird before you took the VC off, then I would assume that the cables are routed wrong.

xjfan0310

The cables are routed correctly. I adjusted the cable and it seemed to work alot better. I took it on a 20 mile test drive thru traffic, backroads and the highway.

The only time it acted up was when I was on the highway going about 74mph and the tach was at about 2100 and intermittently jump up to 2500 like it was trying to shift. The whole time there was no change in pressure on the gas pedal.

Any ideas?

xjfan0310

Any ideas guys??

SNIDELYWHIPLASH

Have you tested the TPS yet?

xjfan0310

No I have been way too busy, in hoping to test it Monday.