snjohns1026

Disclaimer: this is my first Jeep. It’s a 1990 Cherokee XJ. That being said I am also pretty new to working on cars. When I purchased my Cherokee a couple of weeks ago, the guy said I would need to “change the valve on the side of the transmission because it has issues shifting sometimes” now, I am looked high and low on the Internet, and can’t find anything regarding my Jeep and a transmission valve. All I can think of is a transmission modulator/selector valve bit I can’t find anything about my make and model. Any advice? (Would prefer not to take it to a mechanic as I want to learn how to take care of my Jeep myself) thanks!

PatHenry

A 90 XJ uses the AW4 automatic. I've never heard of any valves or any reports of failure. As I understand the shifting is controlled by solenoids that are sometimes in need of replacement.

snjohns1026

@PatHenry See, I didn’t know that. Thanks! So I should check the solenoids? Basically it’s having issues shifting, kind of has a rough idle.

Stickers_XJ

I have a '90 XJ as well. There should be a 7.5 amp fuse under the driver's side dash for the Transmission Control Unit. Absolutely test that fuse before anything else. I bought a kit at Walmart with a fuse tester and a variety of fuses for only a few bucks. Mine also generally has a more rough idle than some other models but I'm not sure if that would be related to the Transmission



It's the one labeled Trans

snjohns1026

@Stickers_XJ thank you! I will absolutely test that when I get off work today and make sure that’s not my issue! (Fingers crossed that it’s just a faulty fuse and nothing worse)

BlueRidgeMark

The solenoids are inside the trans, not on the side. Sounds like he got a bit of knowledge garbled. There are three of them, and to test them you must drop the pan. Not a difficult job, but it does require buying a new gasket. If you have one of the pans that does NOT have a drain plug, do yourself a favor and install a drain plug while you're at it. Most auto parts stores sell a universal plug that can be installed in just about any steel pan. Some suggest not testing, but just replacing. The three are the same part, just operating different parts of the trans.

But before you go to all that trouble, check your trans fluid. If it's dark, try a transmission fluid replacement. See my sig, #3.




Here's a good post on the solenoids:

https://www.cherokeeforum.com/f2/199...7/#post3113066

And a good general troubleshooting post on the trans:

https://www.cherokeeforum.com/f2/aw4...9/#post3140963


These are both from an old-timer who used to work for Chrysler. His advice is rock solid. (Except on the subject of dielectric grease!)

snjohns1026

@BlueRidgeMark i will definitely check the transmission fluid in the morning, I checked my fuse and it’s fine, so here’s hoping that it’s just the fluid and not the solenoids

lawsoncl

"Side of the transmission" makes me think he was refering to the NSS? Also check that the cable between the throttle body and the transmission is correctly adjusted, as that can cause sluggish or harsh shifting if way out of adjustment.

snjohns1026

@lawsoncl sluggish/harsh shifting would describe it pretty well. I will definitely be sure to check!

cruiser54

could be a number of things, but do the basics first and ignore anything the previous owner told you.

You MUST go to www.cruiser54.com and complete Tips 1 through 5 and Tip 10. This could be as simple as a bad ground at the dipstick tube stud.

BlueRidgeMark

That's excellent advice no matter what the issue is.

snjohns1026

@cruiser54 late reply here on my part but I finally got a chance to sit down and look at that list and apply it, started at step 1 but ran into my first problem- there’s nothing attached at the dipstick ground. If anyone has any ideas why that might be or how I can figure out where that ground was moved to that would be great. For now I will refresh the grounds I can find and work from there. Thanks again for your help!

cruiser54

Sometimes they're moved forward to another engine block bolt. It's a cluster of black wires with eyelets.

They originate kinda near the firewall and auto trans dipstick.

downs

You can test the solenoids from the TCU connector or engine bay connector without dropping the trans pan. But do what Cruiser's faq says to do, guy knows his stuff.

cruiser54

Excerpt from Tip 1:

The Renix era XJs and MJs were built with an under-engineered grounding system for the engine/transmission electronics. One problem in particular involves the multiple ground connection at the engine dipstick tube stud. A poor ground here can cause a multitude of driveabililty issues, wasted time, failed emission tests, and wasted money replacing components unnecessarily.

All the components listed below ground at the dipstick tube stud:

Distributor Sync Sensor, TCU main ground, TCU “Shift Point Logic”, Ignition Control Module, Fuel Injectors, ECU main ground (which other engine sensors ground through, including the Oxygen sensor, Knock Sensor, Cruise Control and Transmission Sync signal. All extremely important stuff.