The torque converter solenoid is unpluged, or the wires are cut, or grounded against the body, or solenoid is bad, etc.
The connector is on the rear of the tranny. It's a 2-pin connector, held on with a metal clip. To disconnect it (if it's plugged in), push inward on the metal clip, while pulling the plug off. It looks like this metal clip needs to come off, but it doesn't... just push it inward.
If the plug is connected, pull it off and spray some contact cleaner on the pins (both sides), and re-connect. If that doesn't work, trace these wires back and see if they may be cut somewhere and/or a plug is connected up the line (won't hurt to clean those contacts neither).
If the solenoid is bad, it's a fairly simple fix at home. It's accessible when you take the pan off (change the filter/oil while you're in there). Follow the procedure for changing the filter, and you'll see it in there by following the wires. I don't think that's your problem tho... You're plug is probably disconnected.
2001 TJ; 1999 XJ; 1993 ZJ
Last edited by Yuri; 10-22-2010 at 01:49 PM..
Reason: added content