We recently received a call from one of our wholesale customers that had purchased a carry out transmission for a 2005 Hyundai Santa Fe. The vehicle had been out for a few months and was returned to the installer with a complaint of slipping shifts. Our customer had driven the vehicle and verified the complaint, removed the transmission and called us to send a replacement. With the transmission already removed, there wasn't much we could check, so we sent out a replacement.
The following day, we received a phone call from the installer who informed us that the replacement transmission was doing the same thing as the old one. At this point, we told them that we had to get the vehicle to our store to figure out what was going on.
When I first test drove the vehicle it flared badly on the 2-3, 3-4, 4-5 and had harsh downshifts. It felt like it just hadn't completed its relearn procedure, and after driving several miles, it did start shifting better. I wanted to make sure that it wasn't a heat-related issue, so I disconnected the battery cables and connected the positive and negative cables together for several minutes to clear the adaptive memory.
In the first part of the second test drive, the transmission was shifting very poorly just as when I first drove the vehicle. It took nearly 30 minutes of driving to get all of the shift adapts relearned, and the transmission was working properly again.
When we were finished and the installing shop came out to pick up the Hyundai, it had sat at our shop over the weekend. This leads us to why the Hyundai had come back in the first place. We tried to start it, but the battery was completely dead. Turns out that the combination of a bad battery and a GPS left on under the seat had drained it.
The customer had failed to tell the installer that the vehicle had to be jump-started right before the problem occurred. We installed a new battery and went through the 30 minute test drive/relearn procedure again and all was returned to normal.
Two weeks later, another 2005 Hyundai made it into our shop with a slipping in 3rd-4th gear, burnt fluid, and gear ratio error codes. We installed one of our remanufactured transmissions and on the initial test drive it had very harsh upshifts into 3rd and 4th. We had the battery disconnected during the R&R but we did have a battery memory saver installed to save the presets. I figured that the transmission adapts had not cleared and immediately disconnected the battery cables and tied them together for several minutes. The vehicle still shifted harsh and did not seem to come out of it, so I repeated this procedure again and left it for almost an hour with the same result.
After some additional research, I found that there were four TSBs for this vehicle. All of them were related to the relearning and resetting of transmission adapts. I had read the first two of them when the first Hyundai had come in and since both were almost identical, I did not bother reading the others. That was my mistake. The 4th TSB had the following statement:
The transaxle controller adaptive values are download to the controller EPROM when the ignition key is turned "OFF", then upload when the ignition key is turned "ON". For this reason, the adaptive values cannot be reset by disconnecting the battery cable. The Hi-Scan Pro must be used as shown to reset the adaptive values in order to provide smooth shifts after the following repairs:
- Replace automatic transaxle.
- Reprogram transaxle control module (TCM)
This particular Hyundai was built after 08/01/2004 (see below), which explains why the adapts would not clear with a battery disconnect. Since we did not have a scan tool with the abilities to reset the adapts, we had to take it to a dealer to have the reset procedure done. After that, a lengthy test drive proved everything was operating perfectly once again.