Sonata GL V6-2.5L (1999)
Control Module: All Technical Service Bulletins
A/T - TCM Adaptive Learning & Shift Patterns Modified
Group: TRANSAXLE
Number: 99-40-007
Date: MAY, 1999
Model: 1999 SONATA
Subject
1999 SONATA TRANSAXLE CONTROL MODULE
ADAPTIVE LEARNING AND MODIFIED SHIFT PATTERNS
DESCRIPTION:
The transaxle control module (TCM) logic in the 1999 Sonata incorporates three new features. This bulletin describes these features and includes
relevant service information.
1.
ADAPTIVE LEARNING:
^
Compensates for mechanical tolerance changes which may occur during the life of the transaxle due to normal wear
^
Adapts to the driving style of each driver by modifying the upshift and downshift pattern to obtain the performance desired by the driver
When the transaxle control module (TCM) is replaced or battery power is disconnected, the TCM must begin adaptive learning. Adaptive learning
occurs during normal driving when the ATF temperature is above 60°C (140°F).
SERVICE IMPACT:
After replacing the TCM or after battery power has been disconnected, always test drive the vehicle to complete adaptive learning to ensure customer
satisfaction. Quick adaptive learning may be completed by the following procedure:
^
Drive the vehicle until the ATF temperature is above 60°C (140°F).
^
Accelerate from 1st to 2nd gear at a minimum of 50% TPS (the 1-2 shift will occur above 4500 rpm). Repeat five times.
2.
MODIFIED SHIFT PATTERN AT LOW AMBIENT TEMPERATURE:
^
When the ATF temperature is below -29°C (-20°F), the transaxle is held in 2nd gear to prevent shift shock.
^
When the ATF is between -29°C and -7°C (-20°F and +20°F), the transaxle will shift normally, except the 4-2 and 3-1 skip shifts are
prevented.
^
Normal shifting will return when the ATF temperature increases above -7°C (+20°F).
NOTE:
An open circuit in the oil temperature sensor or harness will result in an ATF temperature indication of -40°C (-40°F) to the TCM. Because of the
low temperature logic of the TCM, the following symptoms may occur:
^
The transaxle will be held in 2nd gear
^
The engagement from Park-Reverse or Park-Drive will be harsh
^
DTC P0713 (A/T temp sensor signal low) may be held in memory in the TCM
^
The scan tool will indicate "Fluid Temperature" as -40°C (-40°F). To check ATF fluid temperature, select "4-Spd Trans" menu, "Codes and Data"
menu, then "Data" menu.
SERVICE IMPACT:
If a customer comments that the transaxle will not shift or does not accelerate as expected when the transaxle is cold, please check the operation of the
ATF temperature sensor.
3.
MODIFIED SHIFT PATTERN DURING COLD ENGINE WARM-UP:
When the engine coolant temperature is less than 35°C (95°F), the shift pattern is modified to require a higher engine speed for the 1-2, 2-3 and 3-4
upshift for two minutes after the engine is started. The purpose of this modified shift pattern is to reduce emissions by reducing the catalyst warm-up
