1993 grand cherokee transmission issues

[mrmopartech]

I have a 93 GC with a 4.0 6cyl and I have transmission issues.Transmission goes good for awhile and then shifts back and firth from 4th to 3rd.Now i have a snap-on scanner and am looking for the transmission connections for this hook up.The scanner says it,s left of the center console but can,t find any thing.Now do you habve to remove the console or is it some where else.Any help would be great.I can be contacted by either sending me a email to me at: penstarperformance@gmail.com or email me your phone number and I call you back on my dime to get this solved.The jeep is in really good shape as the older person who owns it does very little driving so I need to help them asap.Thanks,mrmopartech 514 659 0445cell

 

[TerryMason]

Welcome to Jeepz.com
It sounds like you're trying to find the ODB connector - is that right?


I don't have any experience with this model, but from what I've read it's "side of the transmission tunnel, under the flap of carpet immediately to the right of the gas pedal."

 

[greg92jeepxj]

I don't know how much help this will be but since your GC is a '93 , it may have the AW4 four speed overdrive transmission that was available only that year for the grand Cherokee. This transmission uses a TCU ( transmission control unit ) to control shift solenoids in the transmission . The TCU can be found in any jeep that uses an aw4 transmission such as jeep cherokee's. Perhaps the problem is here . I do not know why a DTC ( diagnostic trouble code ) has not set for this drivability problem but of you can locate one in an auto salvage yard this may fix your problem. Since you have a scan tool , see if you can find a category in its menu to for reading the TCU. This control does in fact feedback with the PCM so there must be some interface with the PCM that the scan tool could pick up. Again , I have never used a scan tool to diagnose the TCU in conjunction with the PCM so I am only suggesting that this is one troubleshooting item you may have success with . The TCU on a Cherokee is located behind and mounted to the lower dash panel that is removable from the dash just above the shift console. I believe the grand Cherokee may have its TCU in a similar location if the lower dash is of a different mounting. It will be a square metal box with a wiring harness plug of I believe less than a dozen wires or so. There is a sticker on it that will read AISIN-WARNER who is the builder of the transmission. It was a joint effort between Nissan and Warner that designed and built this transmission. I am wishing you luck with this problem . Hoping this helps. The only other thing that comes to mind with shifting problems in auto trans is the throttle position sensor of there is a dead spot but I don't feel this is the case with your jeep. Just to rule out , try to find the scan reading of the TPS with the ignition on engine off ( KOEO) and see if the VREF 5V ( voltage reference 5 volts ) is found and the signal back to PCM coincides with accelerator when depressing. It should respond like a wall mounted dimmer switch when turned from low to high and back when dimming lights or increasing brightness. Amtps works much the same. A long shot but worth checking. This is as much as I know of electronic controlled shifting of auto transmissions , hoping this helps. Greg.
P.S.- please refer to the above post from Terry Mason regarding TCU location in the GC. I'm sure his research is bound to be accurate .

 

[mrmopartech]

Today opened up the carpet to find NO transmission connector(supposed to be a blue connector like all the others) nothing any where near the gas pedal.There is a chrysler scan tool hood connector but still NO connector for the transmission codes.Kickdown cable is good and free and spring is working,oil level is goo and this is a chrysler transmission as it has the 904 type oil pan,not the asain/toyota pan.Wondering if this even came with a transmission connector or if there is a web site to locate the connector,mrmopartech
if any one has info and wants to contact me,email me your number and I call you on my dime,thanks again.

 

[greg92jeepxj]

Ok , you have a late production '93 with the 42RE w/lock up torque converter. Contacted my brother whom used to own a '98 GC before it was trashed and he had gone through one trans with it. He mentioned that the TCU for this trans is mounted near the steering column or around the brake pedal bracket . To my knowledge , there is no access to the TCU on any of these transmissions via scan tool . If lime pressure is good ( but must be confirmed with a gauge ) there may be poor communication between the TPS and the TCU . Asked my brother if he checked this on his trans but as I would have guessed , he didn't bother . He may have just swapped a TCU or not when he swapped transmissions. Several years ago , he couldn't be sure. I don't know that I should advise you to swap the TCU unless you can get one cheap at the boneyard.

 

[drewbuddy]

Hopefully this helps. First pic 42\44Re second pic AW-4 transmission
Sorry about bad pics, crappy tablet :redface:
Located underneath drivers side of dashboard, to the left of the steering column

 

[mrmopartech]

I replaced the TPS and output speed sensor and did a road test and it still goes from 4-3-4 every once in awhile.Now I am looking to find a GOOD transmission module to install and try that.Now there might be a problem at the electrical harness going into the transmission and some have said this can have bad connections too.Since there is NO transmission diagnostic connector,and very little info on the scanner to show what,s wrong,this could be a hit/miss problem.A note about this problem,when on cruise control,it never has done the in&out of gears,which makes be believe the transmission ECU is at fault.Now if any one on this web site has one,at a good price,whiling to deal for it,mrmopartech

 

[mrmopartech]

A small note to this problem,I was under the dash removing the remote starter and alarm system that was a night mare,and there was no transmission to scanner hook up connector,weather this is a very early production of just the way they did the canadian models,still to be solved,mrmopartech

 

[mrmopartech]

I am now looking for this transmission module for the jeep 1993 ,part number 560-27218.I am wondering if all the module will fit or it,s a one number for one transmission type???????? mrmopartech call or email me with what part you have,thanks.

 

[mrmopartech]

As a finishing update to the problem transmission,with the going in-out of O/D and back to third gear problem,and after doing some cheap repairs with a new TPS&output sensor,we final found a good TCU for the time being.It,s working and we added in a bottle of lucas transmission additive to solve maybe any problems in the future.The TCU is in a pain in the ass place and there are hard to find,as only buy doing a nation wide search did we find one,had it sent and all worked out good.Any one with a TCU unit,please email me so we can have a spare or two for the next year or so,mrmopartech

penstarperformance@gmail.com

I would like to thank every one that helped in solving this problem for me and the customer,thanks again,MMT