I drive a 2001 Jeep Cherokee and I am having a recent issue where when I shift into reverse, there is a 50/50 chance that reverse gear either
a) works perfectly fine
b) will stall out and die IF I do not give it constant throttle until it begins to idle in reverse normally

To go more into detail on point b, if I were to shift into reverse and this situation occurred, if I were to not give any gas in reverse the car would shut off completely and die and it would either struggle heavily to start again after putting it back in park or not start again at all.
If it does not start on the next try, I have to pop the hood, go to the computer, unplug all three of the plugs, wait a bit, plug them back in again, and it will typically start again the next try.

Alternatively, when it starts stalling in reverse I can use my left foot to go all the way down on the brake, and use my right foot to go very heavy on the throttle and basically use the break and throttle together to fight my way to back out of a parking spot. While I am doing this, the typical behavior is that the reverse gear will phase in and out of having power and then all of a sudden not having power until ultimately something just catches and reverse gear will begin to work perfectly normal again and I can even let off the gas completely in reverse and it will simply just idle perfectly fine like nothing happened at all.

Codes:
I am getting a PO700 code but it is intermittent. Sometimes I start the car and it's there, sometimes I start the car and it isn't, sometimes is not there when I start the car, and then when I try and reverse it appears, and then if I give it a ton of gas like I was talking about above the code will completely disappear and reverse gear will begin to work fine. I can always tell when reverse is going to work fine because if the check engine light is on when I shift to reverse, it struggles, and if it doesn't come on, it works perfectly fine.

What has been tried:
New computer, new battery (terminals have been checked and cleaned), new CPS all done by my local shop
Then I personally checked the grounds and made sure all wires around and near the fuel rail were tied up away from the engine or any direct heat

Also, there is a brand new fuel pump in the car and the fuel pressure has been tested by my shop multiple times

Everything else on the car works perfectly. Driving forward is the same as it always was and I can go anywhere I need to in my car, as long as I am driving in a forward direction.
My shop is stumped and the conclusion as of now is to just drive the car until I can save the money to buy something else since I cant reliably park anywhere that I cannot pull through.

 

The Transmission Control Module on your XJ is mounted along the side of the HVAC Box, right next to the gas pedal. You should be able to disconnect the connector fairly easily. See what that does for ya... Driving forward will still work but you'll need to rev much higher than usual to get it to shift.

Secondly, on the passenger's side of the transmission, the Neutral Safety Switch tells the computer what gear you're in. Be careful removing it, but the grease they used to keep water out eventually dries out, but it's easy enough to disassemble and clean.

 

The transmission computer doesn't actually do anything in reverse, but that P0700 code is interesting. This might sound dumb, but check that the transmission to engine bolts are tight and there is no gap between the bellhousing and the engine. If they are loose, one of the symptoms is stalling in reverse as things shift enough that the crank sensor becomes misaligned and loses its signal. Every time I've seen this, the transmission had been previously removed and reinstalled.

Also check the wiring down to the crank sensor isn't damaged from touching the exhaust.

 

The intermittent reverse issue in your 2001 Jeep Cherokee could be related to transmission fluid, throttle sensors, or the idle control valve.


 

Hi Everyone, was deleting old emails and realized I never came in and posted my solution.

Solution: Wiring. The harness was shorting out on the engine. When you put the car in reverse, things flex and move, and it was just enough to cause a short and cause the car to turn off. This was why it was intermittent, it only flexed enough to cause a short some of the time.

 

Your motor mounts are probably shot. Check the bell housing bolt too, I've seen those be loose and shift the CPS enough to drop the crank signal in reverse.