Crasch

My 97 XJ (AW4) is having problems shifting into OD . The TC locks up fine in third, though. It will shift into 4th/OD sometimes, but maybe only 5% of the time and only if I start cold in 1/2. Any help would be appreciated.

tjwalker

1. Verify fluid is at the correct level on the dipstick, that it is red in color (not brown) and that it doesn't smell burnt.

2. Test your throttle position sensor. It is directly involved with shifting characteristics of the AW4 transmission. More on that below.
--------------------------------

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.

Crasch

The problem started when my mechanic fixed the cruise control. Now, when I do get it to shift into 4th, the cruise doesn't work.

RTorrez1

Personally, I would take it back to whoever worked on it and make them fix it since they screwed it up.

slothlovechunk

I lust bought a used 99 Cherokee and noticed it was having a similar problem to yours. Sometimes it would go into 4th OD but most of the time it would stay in 3rd. Torque converter lockup was fine. I did some searching and found the many many threads about cleaning the NSS. The wiring pinout on the 99 is not the same connector as the AW4 service manual shows it to be. mine looks like the one on this page http://www.naxja.org/forum/showthread.php?t=1072110

I cleaned mine and still couldn't get the reverse lights to work. I did some more searching and found a thread somewhere that pointed me to this page http://www.lunghd.com/Tech_Articles/...tification.htm
My manual says the #10 fuse should be open. The page in the link says its for Transmission range sensor, duty cycle evap/purge solenoid, radiator fan relay, a/c clutch relay, o2 sensor up/downstream relays, back up lamp switch.
I checked my fuse panel and did not find a fuse in the #10 spot. I borrowed the 15 amp fuse from the horn and put it in the #10 spot. Transmission shifting is night and day different. If your back up lights dont work, check that fuse!

rlssteiner

I'm gonna go with lockup soleniode 9/10 its that cherokee have been know to have bad soleniodes after a certain millage. Just my 2 cents

dynaflash

Exactly the same here on my 1998 I just got for my son. No fuse in the #10 slot, put in.a 15 amp fuse and transmission shifts like a dream and the backup lights work. Thanks sooo much for the tip.

TrailerTrash