🔧 Highlander - Automatic Transmission Fluid Drain & Refill

This repair replaces part of the automatic transmission fluid by draining the pan and refilling with the correct Toyota WS fluid. Your Highlander uses a level-check procedure, so the final fluid level must be checked at the correct transmission temperature.

Assumption: This is a drain-and-refill service, not a full flush.

Difficulty Level: Intermediate | Estimated Time: 1.5-2.5 hours

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⚠️ Safety & Precautions

• ⚠️ Work on a level surface only. Fluid level is inaccurate if the vehicle is tilted.
• ⚠️ Support your Highlander with jack stands before going underneath. Never rely on a floor jack alone.
• ⚠️ Transmission fluid can be hot enough to burn skin. Let the vehicle cool before opening the drain plug.
• ⚠️ Toyota WS automatic transmission fluid is required. Do not mix universal fluid unless it specifically meets Toyota WS requirements.
• ⚠️ This transmission is level-checked by fluid temperature. A scan tool that reads transmission fluid temperature is strongly recommended.
• ⚠️ Battery disconnect is not required for this service.

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🔧 Required Tools

You'll need the following tools for this repair:

• Floor jack (rated 3-ton minimum)
• Jack stands (rated 3-ton minimum)
• Wheel chocks
• Safety glasses
• Nitrile gloves
• 10mm socket
• 14mm socket
• 24mm socket
• 6mm hex socket
• 3/8-inch drive ratchet
• 3/8-inch drive torque wrench
• Fluid drain pan (8-quart minimum)
• Fluid transfer pump (specialty)
• OBD-II scan tool with transmission temperature data (specialty)
• Infrared thermometer (optional)
• Funnel with long flexible hose
• Shop towels

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• Toyota WS automatic transmission fluid - Qty: 4 quarts
• Transmission drain plug gasket - Qty: 1
• Transmission fill plug gasket - Qty: 1
• Transmission overflow/check plug gasket - Qty: 1

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📋 Before You Begin

• 🅿️ Park your Highlander on a flat, level surface.
• 🧱 Place wheel chocks behind the rear wheels.
• 📏 Keep the vehicle level if you raise it. Raise the front and rear evenly using a floor jack and jack stands.
• 🌡️ A scan tool is used to read transmission fluid temperature. This tells you when the fluid is warm enough for the final level check.
• 🔁 A drain-and-refill usually replaces about 3-4 quarts, not all the fluid inside the transmission.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Raise and Secure the Vehicle

• Use the floor jack to lift your Highlander at the approved front and rear lift points.
• Place jack stands under the proper support points and lower the vehicle onto them.
• Use wheel chocks to keep the vehicle from rolling.
• Check that the vehicle sits level front-to-back and side-to-side.

Step 2: Remove the Lower Engine Cover

• Use a 10mm socket and 3/8-inch drive ratchet to remove the lower splash shield fasteners.
• Set the shield and fasteners aside in order.
• Tip: Take a photo first.

Step 3: Locate the Transmission Plugs

• Find the transmission drain plug at the bottom of the transmission pan.
• Find the overflow/check plug inside or near the drain area, depending on pan design.
• Find the fill plug on the side of the transmission case.
• The overflow/check plug sets the correct fluid height. Extra fluid drains out when the level is correct.

Step 4: Loosen the Fill Plug First

• Use a 24mm socket and 3/8-inch drive ratchet to loosen the transmission fill plug.
• Do not drain the transmission until you confirm the fill plug can be removed.
• Remove the old fill plug gasket.
• Tip: Fill plug first, always.

Step 5: Drain the Old Fluid

• Place the fluid drain pan under the transmission drain plug.
• Use a 14mm socket and 3/8-inch drive ratchet to remove the drain plug.
• Let the fluid drain until it slows to a drip.
• Use shop towels to clean the drain plug area.
• Install a new transmission drain plug gasket.
• Reinstall the drain plug using the 14mm socket.
• Tighten with the 3/8-inch drive torque wrench: Torque to 49 Nm (36 ft-lbs).

Step 6: Add New Transmission Fluid

• Insert the hose from the fluid transfer pump into the fill opening.
• Pump in about the same amount of Toyota WS automatic transmission fluid that drained out.
• If you cannot measure the old fluid, start with about 3 quarts.
• Install the fill plug loosely by hand for now using a new transmission fill plug gasket.

Step 7: Warm the Transmission Fluid

• Connect the OBD-II scan tool with transmission temperature data to the diagnostic port under the driver side dash.
• Start the engine and keep your foot firmly on the brake pedal.
• Move the shifter slowly through P, R, N, D, and back to P, pausing 3 seconds in each position.
• Watch transmission fluid temperature on the scan tool.
• The level check should be performed when the fluid is roughly 39-45°C (102-113°F).

Step 8: Check the Fluid Level

• Keep the engine running with the shifter in Park.
• Place the fluid drain pan under the overflow/check plug.
• Use a 6mm hex socket and 3/8-inch drive ratchet to remove the overflow/check plug.
• If fluid comes out in a thin stream, let it drain until it becomes a slow drip.
• If no fluid comes out, add Toyota WS automatic transmission fluid through the fill hole using the fluid transfer pump until fluid begins to drain from the overflow/check opening.
• Install a new transmission overflow/check plug gasket.
• Reinstall the overflow/check plug using the 6mm hex socket.
• Tighten with the 3/8-inch drive torque wrench: Torque to 20 Nm (15 ft-lbs).

Step 9: Tighten the Fill Plug

• Use a 24mm socket to install the fill plug with a new gasket.
• Tighten with the 3/8-inch drive torque wrench: Torque to 49 Nm (36 ft-lbs).
• Wipe the fill plug and drain area clean with shop towels.

Step 10: Reinstall the Lower Cover

• Lift the lower splash shield into place by hand.
• Use a 10mm socket and 3/8-inch drive ratchet to reinstall the fasteners.
• Snug the fasteners evenly. Do not overtighten plastic underbody fasteners.

Step 11: Lower the Vehicle

• Use the floor jack to raise the vehicle slightly off the jack stands.
• Remove the jack stands.
• Lower your Highlander slowly to the ground with the floor jack.

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✅ After Repair

• ✅ With the engine running, check under the vehicle for leaks.
• ✅ Test drive gently for 10-15 minutes. Confirm smooth shifting from stop-and-go and light acceleration.
• ✅ Recheck for leaks after the test drive.
• ✅ Dispose of old transmission fluid at a recycling center or auto parts store that accepts used oil and ATF.
• ✅ If shifting feels harsh, delayed, or abnormal, stop driving and recheck the fluid level procedure.

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💰 DIY vs Shop Cost

Shop Cost: $180-$320 (parts + labor)

DIY Cost: $45-$90 (parts only)

You Save: $135-$230 by doing it yourself!

Shop labor rates vary but typically run $100-$150/hour. This repair takes a shop approximately 1.0-1.5 hours.

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