passenger side electric sliding door

My 2001 has a funny problem,the sliding door stops working.registers a code and sometimes corrects itself,to the point of erasing it's codes.I've had it at the dealers about 6 times still no solution,GM says that if it works and no codes......NO FIXING IT. So mine works occationally.GRRRRR.They have extracted a code 22 and 14 (through the piezzo buzzer) which correspond to the optical sensor,and command module respectively.
They (the dealer) have decided to replace by elimination,the first replacement module (which was defective) did not work at all.second one is in the car now,but I haven't had the time to try it. Has anyone else had these problems,if so what was the final solution?

My 2002 will stop mid way when closing - Dealer can't get it to do it while it is in shop. I'm not sure if it is storing a code or not. Dealer has told us this a unitque problem, but that is not what I'm telling them tomorrow after joining this forum! - I am so upset with the amount of other problems we have had with this vehicle with under 60,000 KMS on it. Drives nice, but the "toys" are of poor quality for the price tag - Goodluck in finding the solution