Car won't jump into 4th gear when it reaches 60mph

• Trying to figure out why I can't drive over 60 miles an hour. The transmission shifts fine when the car is warmed, but seems to not want to jump into 4th gear when it reaches 60 miles an hour. The RPMs run about 2,500 3000 before I take my foot off but stay stuck at 60 miles an hour. My overdrive light stays on and I can't turn it off. I'm going to replace spark plugs, spark plug wires, ignition coil, and distributor cap and rotor tomorrow.
  However I do have some important questions about this vehicle that I can't seem to find on the internet...
  1. The transmission fluid was recently changed and the previous owner used Dex Merc instead of ATF 4. I've read online some people saying it's bad and I should drain the Dex Merc out and replace it with ATF 4 and it would fix my problems, but then I seen other people saying the Dex Merc is harmless even if it's mixed put ATF 4... So what exactly is the straight answer here on this here? Should I replace the transmission fluid with ATF 4 and the transmission filter ?
  Or could it be an oxygen problem ? I'm to unplug the O2 sensors and test drive it and see how that is...
  Or could it be an ignition system problem? I'm going to replace the spark plugs, spark plug wires, distributor cap and rotor, and the ignition coil.
  ... And considering on buying a repair manual, which repair manual would you recommend the best accurate for this year and model? I hear I shouldn't run with Haynes...

 

you suspect a transmission issue so you change spark plugs?

the 5.2 uses a 46RH transmission , The recommended (and preferred) fluid for 46RH
transmissions is Mopar ATF Plus, type 7176. Mopar Dexron II fluid can be used for topping off the transmission
fluid level during normal maintenance checks. Dexron II can also be used for refill after
overhaul if ATF Plus is not readily available.

GTG more later

 

No, I don't know what to expect as to why it shifts and runs like that. My first suspicion was the fuel delivery, then ignition system, and then the transmission... Because replacing the transmission is the last thing I can do right now so I'm starting from the bottom and working my way to worst case scenario.

 

Welcome @TinyInkognegroT ....always use OEM recommended trans oil unless your stuck on the side of the hill. IMO don't touch the O2 sensors. Consider getting any engine codes (hidden or otherwise) scanned free at any auto parts store. I like a good Haynes. Use the upload-a-file tab to share some pics

 

When my O/D light is on it means my over drive is turned off and won't shift into over drive. I run mine thatway due to 33" tires and 3.73 gears which will be getting changed to either 4.5 or 4.88 this summer have not decided yet.

 

basically this is a hydraulically shifted 3speed trans with electronics controlling the TCC and OD (4th) gear.
I saw you mentioned the OD off light is always on is that correct?
If correct likely thats your problem and a wiring issue.

Lets try starting with getting codes.
Tell us your wiring skills, can you use a DVOM or test light and a wiring diagram?

 

Okay perfect, I'm going to get back to you after 11:30 Central Time.

 

I don't know what a DV om is, I can use a test light, and I can somewhat read a wiring diagram.

 

Luv that green....my '94 GC Select-Trac was the same color minus the V8

 

Yeah my uncle painted his XJ with a rocky textured paint, kind of the same texture as the interior roof of a home. I want to paint it dill pickle green with that same texture... I also plan on lifting it and some other mods.

 

Can I use the key trick to pull the codes? I don't have a plug-in for OBD scanner. Where are the wires that I should look for?

 

Pull the codes using the key in ignition method and it read-back 45. That was the only code to pull up. On the same page has a list of the codes with the cause next to it. 45 labeled "Overdrive solenoid - open or shorted condition detected in overdrive solenoid circuit."

 

Sound about right ?...

"TRANS OVERDRIVE SOLENOID CIRCUIT fault is set if solenoid control wire is not in its proper state when monitored by PCM (i.e., circuit voltage is low when solenoid should be off or high when solenoid should be on). Possible causes are open or shorted overdrive control circuit wire, open or shorted overdrive solenoid coil, and open 12-volt feed to overdrive solenoid.

Disconnect overdrive solenoid connector on transmission. Using DRB-II in voltmeter mode, probe overdrive solenoid connector, ignition feed circuit (Dark Blue wire). If reading is 10 volts or less, repair open Dark Blue wire.

Perform TEST VER-1. If reading is more than 10 volts, turn ignition off. Disconnect PCM connector. Using DRB-II in ohmmeter mode, probe PCM connector terminal No. 55, overdrive solenoid control circuit (Orange/Light Green wire).
If resistance is less than 5 ohms, repair Orange/Light Green wire for a short to ground.

Perform TEST VER-1. If resistance is 5 ohms or more, check resistance of overdrive solenoid control circuit (Orange/Light Green wire) using an external ohmmeter. If resistance is 5 ohms or more, repair open Orange/Light Green wire.

Perform TEST VER-1. If resistance is less than 5 ohms, reconnect overdrive solenoid connector.
Turn ignition on. Using DRB-II in voltmeter mode, probe PCM connector terminal No. 55, overdrive solenoid control circuit (Orange/Light Green wire). If reading is more than 10 volts, replace PCM.

Perform TEST VER-1. If reading is 10 volts or less, replace overdrive solenoid in transmission."

 

Went to do this testing procedure and found this as soon as I removed the solenoid connector...damaged, shorted, and/or exposed wire, the pink one. How do i repair it ? Cut this connector off and replace it with a new/ salvaged one ? Would I need to clear the computer code error once I do that and how do I do that if so?

 

Okay these wires were melted together under the electrical tape and I didn't see it until I just cut the tape away . Can I rewire these wires together and tape them down with electrical tape okay... Or will I need to go to a salvage yard and cut one and reattach it to these wires?

 

By the way I replaced spark plugs and have the overdrive solenoid connector disconnected, and it shifts better and it got over 60 miles an hour with no problem.

 

I would solder them together and put heat shrink on them then good 3m tape can even put wire look over them and tape it

 

Okay so I can fix it at home rather than pull another from the scrap yard

 

Another note, I had a loud knock when I was pulling back into the parking lot and it came from under the front seats?