2018-2024 Hyundai Tucson Transaxle Solenoid DTCs

Hyundai has released Technical Service Bulletin (TSB) 23-AT-003H-1 to address issues with the automatic transaxle solenoids in several 2018-2024 Hyundai models. This bulletin specifically targets vehicles equipped with an 8-speed automatic transaxle that exhibit a "Check Engine" light and store one or more specific Diagnostic Trouble Codes (DTCs) related to the transaxle solenoids. This TSB supersedes the previous bulletin, 23-AT-003H, to include the Tucson (NX4) model and update parts information.

Symptoms

Owners of affected vehicles may experience a "Check Engine" light illuminating on the dashboard. This warning light indicates that the vehicle's onboard diagnostic system has detected a fault within the automatic transaxle system.

Fault Codes / DTCs

The presence of specific DTCs is key to diagnosing this issue. Technicians will find one or more of the following codes stored in the vehicle's system:

• P074100: Torque converter clutch system
• P074300: Torque converter clutch circuit
• P074800: Pressure control solenoid (PC)
• P075300: Shift solenoid (UD)
• P075800: Shift solenoid (46)
• P076300: Shift solenoid (37R)
• P076800: Shift solenoid (OD&LR)
• P077300: Shift solenoid (28)
• P270900: Shift control solenoid valve (SSA)

Diagnosis / Trigger Conditions

Diagnosis begins with connecting a Global Diagnostic System (GDS) tool to the vehicle and selecting the "DTC Analysis" and "A/T" menu. Technicians will then monitor the solenoid parameters. If the solenoids show continuous and changing output while driving, the wiring is likely free of open/short circuits. However, if there is no continuous and changing output, a wiring issue is suspected.

Further diagnosis involves visually inspecting the wiring harness between the Powertrain Control Module (PCM) or Transmission Control Unit (TCU) and the transmission for any damage, open circuits, short circuits, or improperly inserted pins. If wiring damage is found, the ECM control harness may need repair or replacement. It's important to note that most listed vehicles have an integrated PCM/TCU, except for the Sonata (DN8a) 1.6T and Palisade (LX2), which utilize separate ECU and TCU units.

Repair Procedure Summary

The repair procedure outlined in TSB 23-AT-003H-1 involves several steps to replace the faulty solenoid(s) and potentially the valve body internal harness. The process includes:

1. Preparation: Record preset radio stations, disconnect the battery, remove the battery tray, and remove the undercover below the transmission. The vehicle is then lifted on a hoist.
2. Fluid Drainage and Access: If necessary to access the solenoids, the radiator is drained, and the lower radiator hose is removed. The Automatic Transmission Fluid (ATF) is drained.
3. Transmission Disassembly: The harness is disconnected from the transmission, and the vent hose is disconnected from the oil pan. The oil pan is then removed by unbolting it and gently tapping it loose with a rubber hammer.
4. Harness and Valve Body Removal: Six bolts securing the harness and one bolt for the oil temperature sensor are removed, allowing the harness to be moved out of position. The detent spring bolt is removed (torque: 8-11 lb.ft / 10-13 N.m). Nine valve body bolts are removed in a specific order (outermost to innermost), and the valve body is carefully removed and placed on a clean paper towel to prevent lint contamination.
5. Solenoid and Harness Replacement: The input speed sensor harness is disconnected and replaced with a new one. The 8-digit code on the existing solenoid is recorded. Based on the specific DTC, the related solenoid(s) are replaced. For solenoids 28, 46, 37R, UD, OD&LR, a magnet is used to remove the pin, the old solenoid is removed, and a new one is installed. For SSA, TC, and PC solenoids, a 5mm hex socket is used to remove three Allen bolts securing the solenoid support, allowing for replacement. Solenoid support bolts are torqued to 7-9 lb.ft (10-12 N.m).
6. Reassembly and Fluid Refill: Confirmed O-rings are correctly installed, and the manual shaft is aligned before reinstalling the valve body (torque: 7-9 lb.ft / 10-12 N.m). The detent spring bolt is reinstalled (torque: 8-11 lb.ft / 10-13 N.m). The harness and oil temperature sensor are reconnected (torque: 7-9 lb.ft / 10-12 N.m). A new oil pan gasket (P/N 45283-4G***) is installed, and the oil pan is reinstalled with 14 bolts (torque: 8-10 lb.ft / 12-13 N.m).
7. Final Steps: The lower radiator hose is reinstalled, ethylene glycol engine coolant is added, and the battery is reconnected. The transaxle is refilled with approximately 5-6 quarts of SP4-M ATF through the fill plug. The fluid level is checked using the GDS tool when the ATF temperature is between 122-140°F (50-60°C) with the engine running and the shift lever in "P".
8. Post-Repair Calibration and Test Drive: DTCs are cleared. For UD, 37R, OD&LR, 28, and 46 solenoids, a specific "Solenoid Oil Pressure Data Characteristics Input" procedure is performed using the GDS, inputting the 8-digit code recorded earlier. Finally, the vehicle is test-driven for two key-on/key-off driving cycles, including a full range of upshifts and downshifts, to confirm proper transmission operation and ensure no DTCs return. If DTC P074100 returns after initial repair, the transaxle may need replacement. If other solenoid DTCs return after a wiring harness replacement, the PCM or TCU may need replacement.

Required Tools or Parts

To perform this repair, specific parts and tools are necessary:

• Solenoids: Specific solenoids are required based on the DTC, with PNCs such as 46202A, 46313A, 46313C, 46313B, and 46313D.
• Valve body internal harness: Part Number 46307-4G***
• Oil pan gasket: Part Number 45283-4G***
• SP4-M ATF: Automatic Transmission Fluid.
• GDS (Global Diagnostic System): For diagnosis, data analysis, and solenoid calibration.

Important Warnings

• If the 8-digit code on the solenoid does not contain letters A-F and 0-9, do not enter any pressure data. Instead, follow TSB 16-AT-001-2 to reset the ATM adaptive values.
• If a part is found to need replacement during this TSB procedure and is still under warranty, a separate claim should be submitted using the same repair order. If the part is out of warranty, a Prior Approval request for goodwill consideration is required before proceeding with the work.
• The "Solenoid Oil Pressure Data Characteristics Input" procedure is only necessary for UD, 37R, OD&LR, 28, and 46 solenoids.

Owner Action

If your 2018-2024 Hyundai, such as a Hyundai Tucson, is displaying a "Check Engine" light and you suspect an issue with the automatic transaxle solenoids, it is recommended to schedule an appointment with an authorized Hyundai dealership. They have the necessary diagnostic tools and training to properly identify the specific DTCs and perform the repair according to TSB 23-AT-003H-1.

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NHTSA ID: 10241885