Replace a single shift solenoid in the U660E automatic transmission by removing the transmission pan, valve body cover, and accessing the internal solenoid assembly.

Warnings

Tools required

Parts

• Transmission pan gasket × 1 — OEM recommended (35168-42020 or equivalent)
• Valve body cover gasket × 1 — OEM recommended
• Shift solenoid (specify S1/S2/SL/SR based on diagnosis) × 1 — Use OEM specification
• Transmission drain plug washer × 1 — 90430-12031 or equivalent
• O-rings for solenoid (if not included with solenoid) × 1 — Usually included with solenoid

Fluids

• Toyota WS ATF — 6 qt

Preparation

1. Verify which specific solenoid needs replacement (S1, S2, SL, SR, SLT) using scan tool data
2. Ensure engine and transmission are completely cool
3. Park vehicle on level surface and engage parking brake
4. Raise front of vehicle and support securely on jack stands at manufacturer frame lift points
5. Remove engine undercover and front splash shields to access transmission pan
6. Place large drain pan beneath transmission pan area

Procedure

1. 1

   Drain transmission fluid
   Locate the transmission drain plug on the bottom of the transmission pan. Using a 14mm socket, loosen the drain plug slowly and allow fluid to drain completely into the drain pan. This will take 5-10 minutes. Remove and discard the old crush washer from the drain plug. Clean the drain plug threads and magnet thoroughly.
   ⚠Fluid may still be warm. Wear gloves and be prepared for initial fluid rush when plug is removed.
2. 2

   Remove transmission pan
   Remove all transmission pan bolts in a criss-cross pattern using a 10mm socket. There are approximately 19 bolts around the perimeter. Carefully lower the pan, being aware that residual fluid (approximately 1-2 quarts) will remain in the pan. Clean the pan thoroughly and inspect the magnet for excessive debris. Remove and discard the old pan gasket from both the pan and transmission case.
   ℹ️Excessive metal debris on magnet may indicate internal transmission damage beyond just a solenoid issue.
3. 3

   Inspect and clean transmission filter
   The internal filter screen is visible inside the transmission case. Inspect for debris or damage. On this transmission, the filter is typically not serviceable separately. Clean the exposed valve body surface with brake cleaner and lint-free rags. Ensure no debris or old gasket material remains.
4. 4

   Remove valve body cover
   Locate the valve body cover (lower valve body plate) secured by multiple 10mm bolts. Remove all cover screws in a systematic pattern, keeping track of bolt locations as some may be different lengths. Carefully remove the cover and gasket. You will now see the solenoid assembly and valve body.
   ⚠Some residual ATF will drain from valve body area. Have rags ready.
   Torque spec

   Cover Screws11 Nm (8 lb-ft)
5. 5

   Locate and identify target solenoid
   Identify the specific solenoid that requires replacement. The U660E transmission has multiple solenoids: S1, S2, SL, SR, and SLT. Take multiple photos of the solenoid locations and wiring harness routing. Note the color coding or markings on your target solenoid to ensure exact replacement match.
   ⚠Solenoids are position-specific. Installing the wrong solenoid in a position will cause transmission malfunction.
6. 6

   Disconnect solenoid electrical connector
   Carefully disconnect the electrical connector from the target solenoid. These connectors have locking tabs that must be pressed or lifted before pulling. Do not pull on wires, only on the connector body. Note the connector orientation for reassembly.
7. 7

   Remove faulty solenoid
   Remove the solenoid mounting bolt(s) using a 10mm socket. Depending on solenoid type, there may be 1-2 mounting bolts. Carefully pull the solenoid straight out from the valve body bore. Inspect the O-rings on the solenoid body and the bore in the valve body for damage or debris. Clean the valve body bore with brake cleaner if needed.
   ⚠Do not drop any bolts or debris into the valve body. Use magnetic tools if possible.
   Torque spec

   Sensor Bolts11 Nm (8 lb-ft)
8. 8

   Install new solenoid
   Verify the replacement solenoid matches the original exactly (part number, connector type, and physical dimensions). Lightly lubricate the new O-rings with clean ATF. Carefully insert the new solenoid straight into the valve body bore, ensuring it seats fully. Install and hand-tighten the mounting bolt(s), then torque to specification.
   ⚠Do not cross-thread solenoid mounting bolts. Start bolts by hand to ensure proper threading.
   Torque spec

   Sensor Bolts11 Nm (8 lb-ft)
9. 9

   Reconnect electrical connector
   Reconnect the electrical connector to the new solenoid, ensuring it clicks or locks fully into place. Verify the connector is secure by gently pulling on it. Double-check that no other connectors were disturbed during the procedure.
10. 10

    Reinstall valve body cover
    Install a new valve body cover gasket. Carefully position the cover and install all cover screws hand-tight first. Tighten the screws in a criss-cross pattern to the specified torque. Ensure even seating of the gasket.
    ⚠Overtightening can warp the cover and cause leaks. Use torque wrench.
    Torque spec

    Cover Screws11 Nm (8 lb-ft)
11. 11

    Reinstall transmission pan
    Clean all gasket surfaces on the transmission case and pan thoroughly with gasket scraper and brake cleaner. Install new pan gasket (verify correct orientation if gasket is directional). Position the pan carefully and install all pan bolts hand-tight. Tighten in a criss-cross pattern to specification.
    ⚠Ensure gasket is properly seated before tightening bolts to prevent leaks.
    Torque spec

    Pan Bolts16 Nm (12 lb-ft)
12. 12

    Install drain plug
    Install a new crush washer on the drain plug. Thread the drain plug in by hand to avoid cross-threading, then torque to specification using a 14mm socket and torque wrench.
    Torque spec

    Transmission Drain Plug30 Nm (22 lb-ft)
13. 13

    Refill transmission fluid
    Access the transmission fill port (located on driver side of transmission case, requires removing a plug or accessing through overflow tube). Using a transmission fluid pump, add approximately 5.5-6 quarts of Toyota WS ATF. Start the engine and allow it to reach operating temperature while cycling through all gear positions (5 seconds each). With engine running in Park, check fluid level and add as needed to bring to proper level on dipstick or until fluid drips slowly from overflow when plug is removed.
    ⚠Do not overfill transmission. Overfilling can cause shifting problems and fluid aeration.
    ℹ️Final fluid level must be checked with transmission at operating temperature (160-180°F).
14. 14

    Clear diagnostic codes and test
    Using a scan tool, clear any stored transmission diagnostic trouble codes. Reinstall engine undercovers. Test drive the vehicle through multiple shift cycles, including upshifts, downshifts, and kickdown. Monitor transmission behavior for proper shift timing and quality. Re-scan for any new diagnostic codes.

Reassembly

1. Ensure all electrical connectors are properly seated and locked
2. Verify no tools or rags were left in transmission pan area
3. Check all bolts were torqued to proper specification
4. Ensure engine undercovers and splash shields are reinstalled securely

Verification

• Check for transmission fluid leaks around pan and drain plug with engine running
• Verify transmission shifts smoothly through all gears with no harsh engagements or slipping
• Confirm no diagnostic trouble codes are present after test drive
• Verify proper transmission fluid level at operating temperature
• Test drive vehicle for at least 15-20 minutes to ensure solenoid operates correctly under various conditions

More procedures for this vehicle