Hyundai Repair: Accent transaxel, harness connector, extra pressure

Question
IJ replaced a 96 with a 01 trans axel. I used the netural switch from the 96. Car started and moved foward and reverse in all gears. Drove out of garage and around the block. Got about 1/4 mile. When trans axel tried to go to 3rd from 2nd it slipped into neutral and coasted to a stop. No leaks fluid level if anything i higher than when running. All electrical connections still in place. engine seems to rev up a little when i shift form park to any gear. Should i get another unit.

Answer
The 2001 transaxle has two solenoids that the 1996 transaxle doesn't have.  There's an extra shift solenoid and an extra pressure control solenoid.  Unfortunately, the 2001 transmission isn't compatible with the transmission computer in your car.  To work properly, the transmission will need to be from a 1999 or older Accent.  I don't have access to a parts catalog at the moment, so I cannot check for the changes in transmissions and transmission computers.  But it's even possible that there may have been gear ratio or other changes at any time in the production which could cause your check engine lamp to come on due to a perceived problem that isn't present.

At the very least, you'll need to get another unit from a 1999 or older model year Accent.

Out of curiosity, how did you get the four-wire solenoid harness connector onto the six-pin solenoid connector?