98 ML320 Transmission stuck in 1st gear

[calaxm]

I am brand new to this forum. Any help you can provide would be greatly appreciated. My wife's family has owned our 98 ML320 since day 1. It has 180K miles. We have already replaced the transmission and transfer case once, at a significant expense. Now it is having issues again.

The following codes are coming up:
013 - Speed sensor 3 is faulty
109 - Speed sensor 3 is faulty
148 - The torque converter lock-up clutch causes a sporadic impermissible closing


I have purchased an auto trans conductor plate to replace the old one - in order to fix the faulty speed sensor 3. I anticipate this will solve codes 013 and 109. I am wondering if code 148 is something to be concerned with and how to diagnose/fix that code? Will replacing the auto trans conductor plate fix code 148?


Here is how the car is behaving: Sometimes it feels like its not engaging the gear - you have to press the gas pedal much harder for the car to accelerate. My wife was driving up a hill and barely made it up the hill. Then we turned the car off, and back on, and it drove fine. At other times its fully engaging the gear but refuses to shift out of 1st gear. This is how its behaving right now, for the last few days. Also, currently, when I shift from Park into Drive causes the car to jolt. Shifting into Reverse causes a jolt also, but less so.

By the way, the steering rack is leaking quite fast - I wonder if the steering fluid could somehow be spilling into the transmission and shorting out the computer?

My mechanic is not too familiar with ML320's, but at least he is honest and admits when he doesn't know exactly what the problem is. I'm hoping there is some way to bring this car back to life, as we really can't afford to buy a new or reliable used car right now.


Thank you in advance for your help!
Alex
San Francisco, CA