the ETC module (transmission) is under the drivers lower dash panel. It's mounted vertically.
- You should not mess with that trans. unless you know what you're doing.
And I am pretty sure you can not just plug a new module in - you need to transfer verison coding. I don't recommend trying DIY repairs on that trans. unless you have very good instructions from a trusted source.
A faulty shift recognition switch in the actual shift lever assembly will also cause erratic shifting problems -just like bigcatny stated.