I have a '95 Jeep Cherokee, 2WD, automatic transmission. Runs great. However, when you come to a stop, it doesn't shift down into First. I can shift it down to First, and once rolling, shift it up to Drive, and it shifts through the gears without a hassle, but it just won't shift down to First on its own. For awhile, you could come to a stop, shift the gear to First, then back to Drive, and when you gassed it, it would start out in First, but it stopped throwing even that bone to me. Any suggestions on what's wrong and how to correct it?

All Help Greatly Appreciated,

 

Drain your fluid. Measure how much came out. Add back 8 ounces(half a can) of Seafoam Trans tune and the remaining amount in new ATF. This will help to clean the moving parts in the transmission.

 

I would avoid any snake oil transmission helper fluids. I know some shops use the BG trans conditioner but you're better off just replacing all of it with drain & fills over time. Most people recommend a few miles in between fills to clean out the old gunk / dilute it. I did 3 D&F's while just driving around the block for 5 minutes each time to mix up the old crap, then waited another 100 miles before doing another one.

Just drain and fill it with Dexron III / Mercon fluid from a parts store. You will find a 14mm bolt at the bottom of the pan. Drive the vehicle around to warm up the fluid to get a good drain, stop it, let it sit a few minutes to drain, and unthread that into a pan.

Pour that old (probably black and stinky) fluid into a measuring container (old oil containers measure quarts on the side) and add that amount back in nice clean red new fluid to the trans dipstick via a funnel.

Do not use ATF+4 in your transmission. It was not designed for it. ATF+4 is okay in your transfer case, but not the transmission. Even then, I just keep DexIII/M and put that in the t-case so I could never mix them up if I am working on my car while having a stroke.

People more knowledgeable than myself may know more indepth electrical causes to this, but a few drain & fills will never hurt the trans.

 

Honestly, it could be as simple as changing the fluid a couple of times? As soon as I can, I'm going to work this out. Mind you, I did chain the filter and oil, but this D&F thing, no. Avoid Snake oil. Got it.

 

Do you know the history of transmission fluid changes on this XJ? Is the fluid at the correct level? Is the fluid "red" in color? Does the fluid smell burnt?

I'm a big proponent of keeping up with fluid changes. You could try draining the fluid in the transmission pan, (approximately 3-4 quarts) refilling with Dex/Merc III compatible fluid, drive for a hundred miles or so, then repeat until fluid stays red in color.

Also because this transmission is electronically controlled, the "throttle position sensor" can be in play. More on this very important engine management sensor below. Solenoids are another possibility.
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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 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 fault TPS can report values outside the denied 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 excessing misfires resulting in one or more cylinders being shut down to prevent engine and catalytic converter damage.

 

In addition to the excellent advice on Dexron II/Mercon fluid and tjwalker's fantastic writeup, take a few minutes and do this: https://www.cherokeeforum.com/f2/free-quick-fix-41821/