Jump to content

Automatic Transmission shifting problems


Recommended Posts

 I have an '89 Cherokee Laredo, 4.0 4wd with automatic. I am having shifting issues. when I put in D it wants to start out in like 2nd gear. I have to manually shift it to 1st. once I get going I can shift it back up to D and it shifts fine through the rest of the gears. any suggestions? I have done some searching of the forums but I haven't been able to find anything similar to my issue.

 

Thanks!

Link to comment
Share on other sites

That didn't help. I still have to shift it to first gear at take off and then shift up to D and then it shifts fine though the rest of the gears until I stop again. It like it wants to take off in 2nd gear or something.

 

Thanks again.

Link to comment
Share on other sites

Check the solenoid coils with an ohmmeter first before replacing them. You don't need an FSM to check them for continuity. Takes about ten minutes.
 

I think it's unlikely both TCUs are bad and showing the same symptoms. Recommend testing the AW4 solenoids first. Between the AW4 and TCU there is a harness with a 7-pin connector right on the rear firewall, light gray or white in color. This harness supplies the signals from the TCU to the three solenoids in the tranny that control shifting and TC lockup. The coils on these solenoids can go bad and cause erratic shifting and should be tested with an ohmmeter. Open up the connector and check pins E, F, and G to ground, pin D on the tranny side of the connector. Each should read 13-15 ohms. If not, they have to be replaced which involves pulling the tranny pan. But ohm them out first to make sure they are okay.

Link to comment
Share on other sites

Click on the link in my signature and perform the procedure outlined in Tip 10.

 

OP, yeah, do that, but don't go replacing the solenoids before you ohm them out. That's just not very smart - unless you enjoy wasting $$ and getting douched with ATF.  :shake:

Link to comment
Share on other sites

I haven't been able to get on here for a few days.

 

I wouldn't replace the solenoids without testing them first. I was going to test them the other day, grabbed my ohm meter and the battery was dead. So I took it apart to replace the battery and the whole insides were burnt up. So I will have to buy a new meter.

 

ScottJeep, I know of naxja.org but am not a member. I also own a '88 Comanche and being the MJ and XJ are so similar I didn't think it would hurt to post questions on here about my cherokee as well.

 

Cruiser54, Those tips will come in handy, Thanks!

 

One more dumb question. Where is the NSS Located? I haven't had much experience with the transmission side of things.

Link to comment
Share on other sites

I haven't been able to get on here for a few days.

 

I wouldn't replace the solenoids without testing them first. I was going to test them the other day, grabbed my ohm meter and the battery was dead. So I took it apart to replace the battery and the whole insides were burnt up. So I will have to buy a new meter.

 

ScottJeep, I know of naxja.org but am not a member. I also own a '88 Comanche and being the MJ and XJ are so similar I didn't think it would hurt to post questions on here about my cherokee as well.

 

Cruiser54, Those tips will come in handy, Thanks!

 

One more dumb question. Where is the NSS Located? I haven't had much experience with the transmission side of things.

 

Passenger side of trans. 

Link to comment
Share on other sites

  • 8 months later...

I know it been nearly a year since I posted last. I got busy with work and decided to deal with it for the time being, but now I have new issues. now when I go from park to reverse it doesn't shift from park into reverse and then when I move to the neutral position the trans goes into 1st gear. I can take down to the 1-2 position it started out normal and I can drive it like always by shifting up to D and it shifts all through the gears including overdrive. just no reverse or neutral.

 

I unplugged the TCU then tried it with no changed. The 10 amp fuse there at the TCU is also good.

 

I did get me a new ohm meter. probed E,F, and G with B being ground. I am using an analog meter not digital and when I probe the three prongs on the transmission side the dial zeros out all the way to the right.

 

Can anyone shed some light on this for me please?

Link to comment
Share on other sites

Make sure your AW4 gear shift cable is aligned:
 
http://www.lunghd.com/Tech_Articles/Transmission_and_Transfer_Case/Transmission_Automatic_Shifter_Adjustments.htm
 

 

I did get me a new ohm meter. probed E,F, and G with B being ground. I am using an analog meter not digital and when I probe the three prongs on the transmission side the dial zeros out all the way to the right.

 

Can anyone shed some light on this for me please?

 

Pin D is ground. Verify by testing it for continuity to a good chassis ground point.

Link to comment
Share on other sites

  • 5 years later...

RENIX GROUND REFRESHING

 

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 thdipstick stude 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.Fuel Pump Ground Comanche

If you want to UPGRADE YOUR GROUND AND BATTERY CABLES with custom made parts, contact Paul at www.jeepcables.com 

Neal's cables

Link to comment
Share on other sites

TRANSMISSION CONNECTOR REFRESHING

 

trans plugs

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 itselfTCU fuseTCU location



. 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.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...