A/T - Shift Quality Problems

Group: TRANSAXLE

Number: 96-40-001

Date: FEBRUARY, 1996

Model: ACCENT

Subject
AUTOMATIC TRANSAXLE SHIFT QUALITY

DESCRIPTION:

The Transaxle Control Module (TCM) utilizes the transmission oil temperature sensor to control shift patterns. An ATF oil temperature sensor that does not operate within specification may cause the following abnormal shift conditions:

FORCED 4-3 or 4-2 DOWNSHIFT;

If the ATF oil temperature sensor incorrectly reports the temperature to be 125°C (257°F) or greater, the TCM will command a downshift to 3rd or 2nd gear to reduce torque convertor slip, thus reducing fluid temperature. After a restart, the vehicle may shift normally and no diagnostic trouble codes (DTC) will be stored in the TOM.

DELAYED PARK TO REVERSE/DRIVE ENGAGEMENT w/SHIFT SHOCK;

If the ATF oil temperature sensor incorrectly reports the temperature to be greater than ambient (this most often occurs when cold on first start up), the engagement time from park to reverse or drive may take longer than expected. After an engagement delay of approximately 1.5 seconds, the transaxle may also experience a shift shock when reverse or drive is engaged.

If either of these two conditions is encountered, the ATF oil temperature sensor should be tested using the following procedures:

DIAGNOSIS:

1. Ensure the transaxle fluid is filled to the proper level, (proper checking procedures are described in the shop manual) and that the fluid is in good condition.

NOTE:
ALWAYS use Hyundai Automatic Transaxle Fluid (P/N 00212-11100) or Chrysler Mopar ATF Plus Type 7176. DO NOT USE any type of Dexron or Mercon ATF.

2. Verify the engine cooling system is operating properly and that the engine coolant is filled to its proper level.





3. Verify ATF oil temperature sensor operation using the Scan Tool.





If the Scan Tool is unavailable, a DVOM may be used to test the sensor. Using a DVOM: Remove the battery and battery tray to access the sensor wire connector which is located on the transaxle case near the dipstick. Probe the terminals on the sensor side of the connector. Using the chart compare the ohm value to the temperature.

* Always record the customer's radio stations prior to disconnecting the battery. After completing the test reset the radio to the pre-set stations.

If the ATF oil temperature sensor is not within specification, replace the sensor.


SERVICE PROCEDURE:

1. Drain the ATF and remove the transaxle oil pan.




2. Remove the clip that secures the temperature sensor to the valve-body.





3. Squeeze the tabs of the connector to release it from the transaxle case and pull the connector and sensor from the case.

4. Confirm that the replacement sensor operates within specifications using a DVOM and the chart found in this TSB.

5. Install the new sensor into the clip, then onto the valve-body and torque to 3 to 4 lb ft.

6. Install the oil pan with a new gasket.

7. Fill the ATF* to the proper level according to the appropriate shop manual.

* ALWAYS use Hyundai Automatic Transaxle Fluid (P/N 00212-11100) or Chrysler Mopar ATF Plus Type 7176. DO NOT USE any type of Dexron or Mercon ATF.