Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
A/T - Harsh 4-3 Downshift When Decelerating
1991 Hyundai Sonata V6-3.0LSECTION A/T - Harsh 4-3 Downshift When Decelerating
Group: TRANSAXLE
Number: 98-40-001
Date: JANUARY, 1998
Model: ALL
Subject
HARSH 4-3 DOWNSHIFT WHEN DECELERATING TO A STOP
DESCRIPTION:
Some vehicles may have a harsh 4-3 downshift when decelerating to a stop. The condition occurs when decelerating at speeds below 5-10 mph and is likely to be more pronounced when the automatic transaxle fluid (ATF) temperature is cold. If a vehicle experiences this condition, please follow the diagnostic procedures shown.
DIAGNOSTIC PROCEDURE:
1. Inspect the ATF level in "NEUTRAL" with the ATF at normal operating temperature (70-90°C, 158-194°F).
A. If the fluid level is low, add ATF to bring the level to the top of the "Full" mark.
B. Inspect the ATF color and smell. If the ATF is black and smells burned, remove the transaxle oil pan. If metal particles and clutch material are found in the oil pan, replace the transaxle.
2. Check that the idle speed is within specification. Adjust, if necessary. (Refer to appropriate Shop Manual, under "Fuel System Section", "Service Adjustment Procedures".)
3. Attach the scan tool to the data link connector (DLC) and select the "Transaxle" menu.
A. Select "Codes" and check for diagnostic codes (DTC). If DTCs are present, repair the condition.
B. Select "Data" and "Idle Switch". Check that the idle switch reads as shown. If not, adjust or replace the idle switch. (For adjustment procedures, see TSB # 97-40-029 for 1995-97 Sonata or TSB # 97-40-031 for all other vehicles)
- Engine idling-Idle switch reads "On" or "Closed"
- Engine rpm increased 100-200 rpm above idle-Idle switch reads "Off" or "Open"
C. Select Accelerator Switch" (refer to TSB # 97-40-031 for applicable vehicles). Check that the accelerator switch reads as shown. If not, adjust or replace the accelerator switch according to TSB # 97-40-031.
- Engine idling Accelerator switch reads "Off" or "Open"
- Engine rpm increased 100-200 rpm above idle-Accelerator switch reads "On" or "Closed"
4. Adjust the kickdown servo to the specification shown in the appropriate Shop Manual, under "Automatic Transaxle" section. Refer to TSB # 96-40-016 for 1990-94 Excels and Sonatas, 1992-95 Elantras or 1991-92 for Scoupes.
5. Note:
Proceed with step 5 for vehicles listed in the table. For all other vehicles, replace the transaxle.
If Steps 1-4 indicate that all components are within specification and no DTCs are found, proceed as follows:
- For the vehicles produced PRIOR to the effective date shown, replace the TCM with the part number shown.
- For vehicles produced AFTER the effective date, replace the transaxle.
PARTS INFORMATION:
WARRANTY INFORMATION:
Normal warranty operation codes and times apply.
Number: 98-40-001
Date: JANUARY, 1998
Model: ALL
Subject
HARSH 4-3 DOWNSHIFT WHEN DECELERATING TO A STOP
DESCRIPTION:
Some vehicles may have a harsh 4-3 downshift when decelerating to a stop. The condition occurs when decelerating at speeds below 5-10 mph and is likely to be more pronounced when the automatic transaxle fluid (ATF) temperature is cold. If a vehicle experiences this condition, please follow the diagnostic procedures shown.
DIAGNOSTIC PROCEDURE:
1. Inspect the ATF level in "NEUTRAL" with the ATF at normal operating temperature (70-90°C, 158-194°F).
A. If the fluid level is low, add ATF to bring the level to the top of the "Full" mark.
B. Inspect the ATF color and smell. If the ATF is black and smells burned, remove the transaxle oil pan. If metal particles and clutch material are found in the oil pan, replace the transaxle.
2. Check that the idle speed is within specification. Adjust, if necessary. (Refer to appropriate Shop Manual, under "Fuel System Section", "Service Adjustment Procedures".)
3. Attach the scan tool to the data link connector (DLC) and select the "Transaxle" menu.
A. Select "Codes" and check for diagnostic codes (DTC). If DTCs are present, repair the condition.
B. Select "Data" and "Idle Switch". Check that the idle switch reads as shown. If not, adjust or replace the idle switch. (For adjustment procedures, see TSB # 97-40-029 for 1995-97 Sonata or TSB # 97-40-031 for all other vehicles)
- Engine idling-Idle switch reads "On" or "Closed"
- Engine rpm increased 100-200 rpm above idle-Idle switch reads "Off" or "Open"
C. Select Accelerator Switch" (refer to TSB # 97-40-031 for applicable vehicles). Check that the accelerator switch reads as shown. If not, adjust or replace the accelerator switch according to TSB # 97-40-031.
- Engine idling Accelerator switch reads "Off" or "Open"
- Engine rpm increased 100-200 rpm above idle-Accelerator switch reads "On" or "Closed"
4. Adjust the kickdown servo to the specification shown in the appropriate Shop Manual, under "Automatic Transaxle" section. Refer to TSB # 96-40-016 for 1990-94 Excels and Sonatas, 1992-95 Elantras or 1991-92 for Scoupes.
5. Note:
Proceed with step 5 for vehicles listed in the table. For all other vehicles, replace the transaxle.
If Steps 1-4 indicate that all components are within specification and no DTCs are found, proceed as follows:
- For the vehicles produced PRIOR to the effective date shown, replace the TCM with the part number shown.
- For vehicles produced AFTER the effective date, replace the transaxle.
PARTS INFORMATION:
WARRANTY INFORMATION:
Normal warranty operation codes and times apply.
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.