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Stock XJ Cherokee Tech. All XJ Non-modified/stock questions go hereXJ (84-01)
All OEM related XJ specific tech. Examples, no start, general maintenance or anything that's stock.
I'm back, like a bad case of herpes. This time with a bad case of loss of drive.
I always drive in permanent 2WD, she's a 1997, RHD, 4.0 XJ Automatic.
Yesterday I noticed she felt slightly underpowered, I'd increase the revs but she felt like she was lacking a bit of grunt. I was in a rush so didn't pay any more attention to it than that.
This morning, I put her in Drive, she hardly moved and I had to rev to get her to trickle forward, I then dropped into 3, which did a little better, then I dropped her into 1.2 and she started to pull away as she would normally, I then flipped her into 3 and drove around with her in 3 for the rest of the day. Except when pulling off and I'd put her into 1.2.
Putting her into Drive at any point lost all power and you'd have to rev her till she screamed to move.
She has transmission oil... That's the only thing I've managed to check.
I'm a landy man, so this is my first cherokee.... it's been an experience but she's great fun.
Start by checking the fuse for the transmission computer. If the trans computer doesn't have power, it doesn't activate the shift solenoids, and you get exactly the manual shifting you described. With no power and the shifter in D, it's trying to run in 4th gear.
It's also possible, although very rare that the trans computer has died. I've only seen a few confirmed cases of bad TCMs, and usually the problem was elsewhere. A bad shift solenoid can also cause it to start in 4th gear.
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
, which is available at Lowe’s and other stores. Reinstall all the wires to the stud and tighten thhttps://i0.wp.com/cruiser54.com/wp-content/uploads/2015/10/dipstick-stud.jpge 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
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
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
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
also.https://i1.wp.com/cruiser54.com/wp-content/uploads/2015/10/Fuel-Pump-Ground-Comanche.jpg
If you want to UPGRADE YOUR GROUND AND BATTERY CABLES with custom made parts, contact Paul at www.jeepcables.com
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
. 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.
Cruisers advice on refreshing ground connections i always relevant. You'd be surprised how many weird issues that can fix! I think your next step should be testing at the trans computer connector. Unplug it and making sure you have power on pins 25/26, good ground on pin 24, and checking the resistance of the shift solenoids, in particular the #1/A solenoid (pin 12). With it plugged in and key on, you should still have voltage on pins 25/26, and have voltage on pin 12 powering the A solenoid to command 1st gear. I believe the picture above on the location of the TCU is correct and it didn't move to the drivers side until 98. I don't think a 97 has the fuse in the wiring harness like the earlier years did though.
03-06-2021, 12:23 PM
Loss of drive causing my hair to fall out
