2000 XJ AW4: Intermittent No Reverse

I've tried to find the answer but I'm not finding anything specific to my problem.

I'm having trouble with the occasional no reverse/long engagement. When it is not shifting into reverse, if I drive down the road and let it shift through a couple gears in drive and try it again, I can get in reverse no problem.

There are times when I can get in and I can get into reverse no problem. It seems to have the most trouble after either sitting for a couple of days or after sitting for a couple of hours after driving.

I have done a filter/fluid change and installed an auxiliary transmission cooler with no luck. The only thing that has worked so far is TransX, but even then it's only for a couple of weeks before the reverse problem comes back.

I finally got around to reading codes and got the following:

P0751-Shift Solenoid A CKT performance or Stuck Off
P0756-Shift Solenoid B CKT performance or Stuck Off
P0740-TCC Circuit Malfunction

Well you might get lucky with some bad connections, but you'll probably need to pull the pan and replace some parts! Solenoid failure is a fairly common issue.
https://www.quadratec.com/jeep_knowledgebase/article-39.htm

RCP Phx said:

Well you might get lucky with some bad connections, but you'll probably need to pull the pan and replace some parts! Solenoid failure is a fairly common issue.
https://www.quadratec.com/jeep_knowledgebase/article-39.htm

Click to expand...

Could very well be solenoids, but they shouldn't cause a no-reverse issue.

Another update: I cleared the codes and these are the ones that came back

-P1698: This code seems to tell us more information but I'd like some input.
-P0740

Those say torque converter not locking up and a bad/no connection from the TCM (related, very possible).

Have you actually checked the fluid?

Afireinside said:

Have you actually checked the fluid?

Click to expand...

Bad solenoids shouldn't cause problems with reverse. The solenoid codes are caused by the trans computer seeing the output shaft at a different speed than it expects based on what it's doing with the solenoids and the input speed. So for example, it's commanding 1st gear but it looks like it's in forth, or the t/c isn't locking up. A mechanical problem and slipping could potentially cause these codes as well.

Try unplugging the trans computer and see if the reverse problem is still there. That will guarantee it's not a solenoid problem. With the intermittent nature, I wonder if you're looking at a plugged up valve body?

lawsoncl said:

Bad solenoids shouldn't cause problems with reverse. The solenoid codes are caused by the trans computer seeing the output shaft at a different speed than it expects based on what it's doing with the solenoids and the input speed. So for example, it's commanding 1st gear but it looks like it's in forth, or the t/c isn't locking up. A mechanical problem and slipping could potentially cause these codes as well.

Try unplugging the trans computer and see if the reverse problem is still there. That will guarantee it's not a solenoid problem. With the intermittent nature, I wonder if you're looking at a plugged up valve body?

Click to expand...

Because of it being intermittent, that's why I am skeptical of it being an electrical problem, especially if that trans fix stuff temporarily helps the problem. I'll unplug the TCM and see if I can recreate the problem that way.