Over the weekend i changed my oil pan gasket and had to take off my starter. After I put it all back together i drove it around for a day where i noticed weird electrical issues. Then it would not turn on. After cleaning and stuffing the positive cable back into the terminal it turned on like nothing. BUT now when I put it into drive it wont move. Reverse 1-2 and 3 WORK just fine but Drive will not work. I took it to a shop and they said the transmission needs to be rebuilt. Up till this point the transmission has worked and shifted just fine besides a clunk every now and then. ANY IDEAS???

 

Does drive work once you get moving? If so check the TCM fuse.

 

Yes, check power first to the transmission computer if it feels like it's trying to take off in 4th gear. What model year are we talking about? The fuse is in different places or labelled differently depending on the year.

If the transmission computer doesn't have power, you'll get reverse in (R), first in (1-2), 3rd in (3), and 4th in (D) - essentially manual shifting. In fact, that's actually the test to see if the trans is in good shape mechanically, and in fact probably doesn't need a rebuild. I would avoid any shop that jumps straight to wanting to rebuild the transmission.

 

I have not tried while moving. Just moved it using 1-2 and 3 but will try drive once it gets going.

 

Interesting I will try this. Im not sure if i am stubborn or what but i do not believe it needs to be rebuilt either. It happened to go out after driving around for a day with a bad positive connection. Every shop jumps to it being a jeep and needs to be rebuilt. It is a 1996 jeep cherokee sport

 

I cant find the TCM fuse anywhere but did find the TCM. It is a 1996 jeep cherokee sport

 

I think on a 1996, that it's fuse 21 (10-amp) in the PDC under the hood. With the key-on, you should have power at the TCU on pins D14 (red wire) and D16 (yellow wire).

 

I checked the fuses and they are all fine. Becoming convinced I fried my TCU or sum

 

It's rarely the TCU. Do you have a voltmeter to do some testing at the TCU connector. The TCU is under the passenger side of the dash, bolted to the back of the lower trim panel near your knees.

You're looking to see if you have power on pins D14 and D16 with the key on. Check that D3 and D7 have a low resistance connection to ground, ideally under 1.5 ohms. If not, start by looking at the bolt near the dipstick where a whole bunch of wires get grounded. With the TCU plugged in and the key on, you should have 12-volts on C16 and nothing on C14 or C15, to correspond with the TCU commanding 1st gear.

 

I checked the connector with a volt meter they are all fine. Still jus have to shift it up and down to drive it

 

If the trans shifts up and down correctly on the open road, it almost certainly does NOT need rebuilding, but is a control issue

It may be wiring, connectors, TCM, or possibly solenoids

To test if it is working correctly, on a flat open road, with mild acceleration it should change 4 gears, then the OD solenoid engages about 55mph, dropping revs about 10%, (so its really like 5 changes)

This can be subtle to detect, but would prove all solenoids are operating

If there is a control issue, it may not engage OD

I guess it may be possible for it to be in the valve body, but I would test all electrical matters first

A backprobe can be made to detect output from the TCM (that power solenoids)

 

With the shifter in (D), it's trying to start out in 4th gear, right? The voltages and resistances at the connector checked out? Power on D14, D16, and and C16 with the key on? Unplug the TCU and check the resistance on C14,C15,and C16 and they're all around 15 ohms?

 

Yes starts off in 4th gear. im going to recheck but whenever i used a measure meter, if they have the correct amount of flow i am not sure. I had the setting on Ohms and numbers changed on each square on the connector. I tried to use the volt meter on the TCU and don't know if i did it wrong but got no energy

 

I heard it could be the valve body. I will try to hit 55. I can put it in D and feel the shift into 4th but even going over 45 it feels like it is not going to shift. Im hoping it is a electrical issue because i drove for a day with a bad terminal connection and the car did not run. After tightening it it turned right on but then started having this issue. Never had any tranny issues in the one year i had it.

 

I FIXED IT! I changed all my battery terminal cables and cleaned every ground connection i could see and poof it turned on. Thank you all for steering me towards it being an electrical issue