TECHNICAL SERVICE BULLETIN: 8AT (A8LR1-SBW) SOLENOID VALVE REPLACEMENT AND TCU LOGIC IMPROVEMENT - This bulletin provides the procedure to replace two (2) solenoid valves (35R and 4&OD) and improve the gear shift logic of the Transmission Control Unit (TCU) on some 2015-2016MY K900 (KH) vehicles, equipped with Tau 5.0L engine and 8-speed automatic transmission w/Shift-By-Wire (A8LR1-SBW), which may exhibit symptoms of abnormal shift shock during an upshift (2nd-->3rd, 3rd-->4th, 4th-->5th). This condition occurs on vehicles with mileage over 12,000 miles and may be due to possible premature wear of the solenoid valve. To correct this concern, replace the 35R and 4&O/D solenoid valves with added “H†ventilation port, perform TCU relearn, and, if applicable, apply the improved logic to the Transmission system using the KDS ECU Upgrade function as described in this bulletin.
