Getting check engine light, speedometer falling to zeroand transmission selector sequencing. My mechanic has replaced speed sensor, control unit and sensor in differential but problem continues. He is frustrated and I am spending lots of money. Any ideas?

Which module did the 232 code come from?

Sorry to be so slow getting back to you. Don't know what module is generating error. Replaced speed sensor, something in differntial and master control unit to no avail. Get check engine light, transmission mode lights sequence and on occasion the speedometer goes to zero and tranny will not shift from low gear.

Most often the car runs fine even with these lights.