Thanks Guess I figured something like that out last century. So I guess the 89 has C-clips but my 89 doesn't. (pretty sure that was that Jeep), (and and the diagram of the heater blower inside, Rrich posted in some pissing match, for a 90 was wrong). I couldn't back up DJB, caus I have 89 on my sticker.

Anyway ZUK needs overdrive. I wonder if the signal to the solenoid could be checked.

 

 

I took the cherokee out today with the old tcu in place, everything worked including overdrive. I stopped along side the road and changed out tcu with (91)donor and same problems returned ,no passing gear or up shift with more gas applied, very early shift from first to second and no overdrive. stopped again and installed old tcu and it worked for about 20 miles of hiway driving. cruising along at 50mph at 1500rpm (31" tires), it suddenly popped out of overdrive (2400rpm)and no shifting untill 3500rpm again. I'm starting to think 91 tcu may not work and my old unit has a electronic break down once it's warm. the tcu ground refresh was done same time I replaced all other grounds. now that I think of it, I don't recall if 91 donor truck had the power/comfort switch on the dash.

 

Cruiser will be up at some absurd and cold Hour. I think the "comfort" left in 91. I'm not surprised the 91 TCU has issues...allot changed there. Might be AMC to Chrysler. OK guys, does the NSS tell the ECU it's in drive? How's that work?

A side note Zuk..the PO of my Jeep was sold a TCU. I'm not sayen it was bad, just that someone got him to buy one. (spendy shop). Your Jeep starts fine in neutral or park, and your reverse light's work?

Just curious..what tells the ECU/TCM you put it in drive, and is that working.

ZUK. a bonehead Idea. When it screws up, slam the shifter a bit, really "seat" it in drive again and see if there is any change.

 

The wife laughs at me every time it acts up, as I first start switching the power switch ,then I pull over and throw in park, shut off the engine ,press the gas pedal to the floor, restart the motor and pull and push shifter into drive then drive off cusin because it still won"t shift. the 91 tcu acts like it should work, starts in neutral/park,it won"t go into reverse or drive unless foot is on the brake, it has back up lights when in reverse as does the original tcu. I found a tcu from a 89 on the local craigslist, will pick it up tomorrow and give that a go.

 

Cool!, (how much?), and my .02....no, it's something else...hope I'm wrong!

 

I'm up. 1/2 cup of coffee. I slept in til 5:30 this morning.
Get the 89 TCU.
Make sure the connector is clean, has no corrosion, and the pins are not bent or retracted. Pull the fuse in the yellow tape on the harness and make sure it's perfect. Right near there in that harness is a little resistor looking thing. Make sure it's not screwed up in any way.

As 67GMC stated earlier, it could be your speed sensor. Bare minimum unplug it and clean the connector.

 

OK, you caught up with me after a case if ice. He's changed the TCU a few times.

4th gear - solenoid 1 OFF, solenoid 2 OFF
Lockup - Solenoid 3


???can only guess #3 should be on?....Over my head here, but I'm perfectly comfortable asking, what wire energizes #3 solenoid?

Radi, fredgr, and others, you might re visit here> https://www.cherokeeforum.com/f2/get...-29509/index2/

I think the TC lock up color is there? Dam I burned my beans. Again.