lawsoncl said:
The first thing to do is see what code the computer is throwing. More than likely that will tell you exactly what the problem is. I'm guessing a bad t/c solenoid or perhaps TPS sensor.
He already replaced the TPS on June 10th.
Sounds like you are getting all 4 gears, but not getting the TC lock up, which is easly confused (sort of feels the same) with engagement of the 4th OD gear. If you are getting gears 1,2 & 3 then the solenoids #1 & 2 that allow you to get gears 1,2 & 3 must be working which means OD must also be working (unless the internal OD clutch is bad, which is doubtful). Solenoid #3 controls TC lock up which normally engages in third gear if it gets the chance (it must be at a steady speed in third gear), but du ring acceleration is delayed until 4th (OD) gear when you reach a contstant speed.
Sounds like its time to test the #3 solenoid resistance to ground, power off, should be something like 11- 15 ohms. If it is OK, then the TCU wire from the TCU to the number 3 solenoid is the next most likely suspect. It should also read 11 -15 ohms to ground. It is pin #C14 on the TCU cable. It is easiest to check the TCU pin C14 and veryify the solenoid and wiring all at once. If the resistance is too high or low, then check it at the transmission itself. You need to pull the tranny pan to get directly to the elcectric solenoid, but you could check the wiring at the tranny connection before droping the pan.
Also check the ground wire on the TCU side of the TPS to the battery negative post ground. It should read less than 1 ohm. Then check the TCU ground wire the same way, it should be less than 1 ohm to ground. On the TCU bulk connector the TPS ground is Pin D3. D7 is the other TCU ground.
Also check the brake light switch, if the brake lights are stuck on, the brake light switch is stuck on and the TC will never lock up as the TCU reads the brake switch to unlock the TC.
The TCU on the older jeeps is just behind the lower dash trim under the glove box, little silver box, pasenger side, and is probalby still located there on the 97, if not someone will post a correction.
Neutral safety switch also tells the computer where the shifter, so the electrical problem could be there as well.
That should keep you busy for a while....let us know what you find.
