AW4 Driving Issue

[jdritchey98]

I have an 89 MJ 4.0 4x4 Auto Aw4.

The problem I'm having is when I get in to go somewhere I back the truck down my driveway shift into drive or 1st and start going down the road. I have to go up a hill either direction I go. When I start going up the hill I get to about 10mph and then the truck acts like its in neutral. I can give it some more gas and it still doesn't go. It will actually roll backwards down the hill while in drive. If I shift it into third it changes gear just fine but still acts like its in neutral. After some more revving and shifting back and forth it finally jerks like something coming unstuck and then drives like it should the rest of my drive. My driveway is an incline as well but the truck also does this after being parked on flat ground while I'm at work.

 

My TPS tests good. All 3 transmission solenoids ohm good. The NSS is also good. It does this whether the TCM is hooked up or not. Fluid level is also correct. Only thing I havent done is pull the pan and check the screen or try adjusting the tv cable.

 

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[cruiser54]

Adjust the TV cable. 

 

Also do this:

Over near the transmission dipstick tube are 2 rather large connectors. One is black and goes to the NSS and the gray connector goes to the transmission itself

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. These 2 connectors carry all the info between TPS, TCU, NSS, speed sensor, and transmission solenoids.

Unplug each one, visually inspect for corrosion or bent pins, spray them out with electrical contact cleaner and plug them back in.

Additionally, if your Jeep is an ’87 to ’90 Renix, it’s always a good idea to reach up under the glovebox area and unplug the connector to the TCU and spray it out along with the receptacle of the TCU. While you’re there, find the fuse right in that area for the TCU. Remove it and spray out it’s receptacle and clean any corrosion from the fuse.

 

 

And this:

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.

The factory was aware of the issues with this ground point and addressed it by suggesting the following:

• Remove the nut holding the wire terminals to the stud. Verify that the stud is indeed tightened securely into the block. If the whole stud turns, you can use a 7/32″ six point socket or wrench to hold it so the nut can be removed. Worst case, cut the wires and remove the stud and nut. Install new terminal eyelets on the wires when going back together.  Scrape any and all paint from the stud’s mounting surface where the wires will attach. Surfaces must be clean, shiny and free of any oil, grease, or paint.
• Inspect the wire terminals. Check to see that none of the terminals are crimped over wire insulation instead of bare wire. Be sure the crimps are tight. It wouldn’t hurt to re-crimp them just as a matter of course. Sand and polish the wire terminals until clean and shiny on both sides. Apply a liberal coating of OxGard, which is available at Lowe’s and other stores. Reinstall all the wires to the stud and tighten the nut down securely.

While you’re in that general area, locate the battery negative cable which is fastened to the engine block just forward of the dipstick stud. Remove the bolt, scrape the block to bare metal, clean and polish the cable terminal, apply OxGard, and reattach securely.

Another area where the grounding system on Renix era Jeeps was lacking is the engine to chassis ground. There is a braided cable from the back of the cylinder head that also attaches to the driver’s side of the firewall. This cable is undersized for its intended use and subject to corrosion and poor connections at each end.

• Remove the cable end from the firewall using a 15mm wrench or socket. Scrape the paint off down to bare metal and clean the wire terminal. Apply OxGard. Reattach securely.
• Remove the other end of the cable from the rear of the head using a 3’4″ socket. Clean all the oil, paint and crud from the stud. Clean the wire terminal of the cable and reattach securely with a liberal coating of OxGard.

2 STRONG suggestions regarding the ground system:

I prefer to add a #4 gauge cable from the firewall to a bolt on the rear of the intake manifold, either to a heat shield bolt or fuel rail bolt. A cable about 18″ long with a 3/8″ lug on each end works great and you can get one at any parts store already made up. NAPA has them as part number 781116.

A further improvement to the grounding system can be made using a #4 cable, about 10″ long with 3/8″ terminals at each end. Attach one end of this cable to the negative battery bolt and the other end under the closest 10mm headed bolt on the radiator support just forward of the battery. NAPA part number 781115.

For those of us with Comanches, it’s very important to remove the driver’s side tail lamp assembly to access the ground for the fuel pump. Remove the screw holding the black ground wire. Scrape the paint from the body and corrosion from the wire terminal.  Add a 10 gauge wire, with an eyelet on each end, from that grounding point to a bolt on the frame. Better yet, on both Cherokees and Comanches, complete Tip 29 for the best fuel pump grounding. Be sure to scrape all mounting points to bare metal and apply OxGard also.

If you want to upgrade your ground and battery cables with custom made parts, contact Neal at www.meanlemons.com 

Revised 02/04/2017

 

 

 

 

[Manche757]

JDRitchey. Any progress? What you describe is shifting delay. Valve body issue. Local Chrsyler/Jeep dealer guys call it the pissing valve. It is not releasing hydraulic fluid to shift to another gear. Big bucks. Not the easiest fix but replace with 5 speed. Much more fun to drive.  

[jdritchey98]

I did most of what cruiser has mentioned above when I first got it. I can somewhat drive it with the TCM unhooked but it still does it. I also have an 87 MJ same everything but it's a 5 spd ax15. Was planning on fixing up the 87 but there's quite a bit of rust and I got rear ended in a parking a lot a year ago and insurance wouldn't do anything. A friend of mines neighbor has had this 89 for a while and he got put in a nursing home and I was told they was selling truck or scraping it so I bought it. Only had it a couple of months still messing with a lot of it don't get much time to work on it.

 

Gonna try adjusting the tv cable tomorrow morning and see if it helps any. Will update after I try that. A mechanic friend of mine told me to check the screen/filter to see if it was dirty but haven't had time to do that yet.

Picture is the 89. 87 is red one in background.

 

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[Manche757]

A plugged screen could cause shift delays but from what you expressed, you are way past that. Hydraulic fluid is not being released to other gear valve. It is not likely to leave you stranded. You just have to wait for the fluid to be released or pissing. FYI, a successful Aamco shop here tries to solve a transmission problem 3 times then throws in the towel and overhauls it. Google valve body and see what you are up against and why it is big bucks. Someone wanting automatic on a Comanche is alien to me but there are threads here for some owners wanting to do just that. Check for one. Probably not mucho bucks and you will be done with automatic Jeep problems that ran through the 90s. You might hate me for busted knuckles installing clutch and thus and such but your C will be more fun to drive. And errrr don't destroy the banged up 87. A highly noxious thought.

[jdritchey98]

A plugged screen could cause shift delays but from what you expressed, you are way past that. Hydraulic fluid is not being released to other gear valve. It is not likely to leave you stranded. You just have to wait for the fluid to be released or pissing. FYI, a successful Aamco shop here tries to solve a transmission problem 3 times then throws in the towel and overhauls it. Google valve body and see what you are up against and why it is big bucks. Someone wanting automatic on a Comanche is alien to me but there are threads here for some owners wanting to do just that. Check for one. Probably not mucho bucks and you will be done with automatic Jeep problems that ran through the 90s. You might hate me for busted knuckles installing clutch and thus and such but your C will be more fun to drive. And errrr don't destroy the banged up 87. A highly noxious thought.

I definitely don't plan on destroying the 87. It basically needs a new bed on it as well as floor pans. I might consider converting the 89 to a manual. I know I prefer a manual over an automatic. I know a lot more about manuals than autos.

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[Manche757]

On 8/21/2018 at 9:37 PM, jdritchey98 said:

I definitely don't plan on destroying the 87. It basically needs a new bed on it as well as floor pans. I might consider converting the 89 to a manual. I know I prefer a manual over an automatic. I know a lot more about manuals than autos.

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How did you solve the tranny problem?

[HOrnbrod]

OP, pull the pan and change the filter. 

[Dando]

Adding this just for more info, I had this same exact problem a few years ago. I solved the problem by pulling the pan, changing the filter, and of course fresh fluid. That is the only time I’ve ever opened this transmission and it has over 400k on it now and still going. 

 

I would recomend anyone try that first before jumping to the conclusion that your trans is bad. Took less than an hour to solve this problem for me. 

[omega_rugal]

so the truck actually rolls back in gear? wow that´s some major internal damage like clutches not grabbing but if happens after $#!&fs the somethign is stuck/plugged in the vavle body...

 

try changing fluid and filter...

 

but your aw4 seems to be on its last leg