Shift Pointers
- Subject: Flare on 2-3 shift
- Unit: Hyundai KM series
- Essential Reading: Rebuilder, Diagnostician
- Author: Pete Luban, ATSG, Transmission Digest Contributing Editor
I was handling a call on the ATSG Tech Line about a 2000 Hyundai Elantra that had a complaint of a flare on the 2-3 shift.
Ordinarily, a KM unit with a 2-3 flare could have a problem with servo-release pressure, usually caused by the computer not shutting off the pressure-control solenoid quickly enough. There could be a problem with the servo switch if it were stuck. In other words, these are the usual components that could cause a 2-3 flare on a KM unit.
In this situation it was none of the usual items. It was, believe it or not, the transmission-fluid-temperature sensor. As I looked further into this, sure enough, I found factory bulletin 00-40-010 dated August 2000.
It seems that this vehicle had stored a P0712 for a shorted ATF-temp sensor, which causes the TCM to create a flared 2-3 shift in this vehicle model. Computer strategy seems to be the culprit here.
As I read the bulletin, I found other unusual computer strategies in play on various Hyundai model years, all related to the ATF-temp sensor and in what manner it failed.
If the ATF-temp sensor fails open and stores code P0713, the complaint would be a harsh garage shift from park to either drive or reverse and no converter-clutch application.
If the vehicle were a 1996-2000 Elantra or Tiburon, or a 1995-2001 Accent, the complaint would be no 4th gear.
If this were a 1999-2001 Sonata, the complaint would be no upshift past 2nd gear.
Should the ATF-temp sensor become shorted and a P0712 be stored, the 2-3 flared-shift complaint would affect 1996-2000 Elantra and Tiburon as well as 1995-2001 Accent.
In the event this happens to you, the part number of the ATF-temp sensor for the 1996-2000 Elantra and Tiburon and the 1995-2001 Accent is 46386-22600.
The part number for the 1999-2001 Sonata is 46386-39050.
