My service w/wrench light randomly comes on. Sometimes it shifts hard, sometimes it doesn't. The check engine lights is more frequently coming on with the other light. No one seems to be able to pull a code. My brother read that another owner had the same problem and replaced the control solenoid; it solved his problem. I was told that to replace it; you just need to remove the filter and it's right behind it. My mechanic claims the transmission has to be dropped to go into the side. Who is right?