🔧 Highlander - Transmission Fluid Drain & Fill

You’ll be doing a drain-and-fill on the automatic transmission, not a full flush. This replaces a good portion of the old fluid and restores shift quality while being safe for your transmission.

This transmission is “sealed,” so you’ll set the fluid level through a check/overflow plug at a specific temperature, not with a dipstick.

Difficulty Level: Advanced (for a beginner) | Estimated Time: 2–3 hours

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⚠️ Safety & Precautions

• ⚠️ Work only on a solid, level surface. The fluid level procedure requires the SUV to be perfectly level.
• ⚠️ Use a floor jack and jack stands correctly. Never rely on the jack alone to support the vehicle.
• ⚠️ Transmission fluid and the exhaust can get very hot. Let the vehicle cool enough so you won’t burn your hands.
• ⚠️ Keep the engine area clear when the engine is running in gear-check mode. Feet and tools away from the wheels and belts.
• ⚠️ Automatic transmission fluid is slippery. Immediately wipe spills from the floor and from the underside of the SUV.
• ⚠️ Avoid skin contact with used fluid. It’s harmful; use gloves and wash up afterward.
• ⚠️ This is a late-model SUV still likely under warranty. Using correct Toyota WS fluid and proper procedure is important to avoid warranty issues.
• ⚠️ Battery disconnect is not required for this job.

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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, set of 4)
• 🧰 Wheel chocks
• 🧰 Metric socket set (8mm–19mm)
• 🧰 10mm socket
• 🧰 14mm socket
• 🧰 3/8" drive ratchet
• 🧰 3/8" drive torque wrench (5–80 ft-lb range)
• 🧰 Hex/Allen bit set (4mm–8mm)
• 🧰 6mm hex bit socket
• 🧰 Trim clip removal tool
• 🧰 Flathead screwdriver (medium size)
• 🧰 Oil drain pan (at least 10-liter capacity)
• 🧰 Fluid transfer pump or hand pump (for ATF)
• 🧰 Long plastic hose (to fit pump outlet)
• 🧰 OBD2 scan tool with live data and transmission fluid temperature (specialty)
• 🧰 Shop rags
• 🧰 Parts cleaning brush
• 🧰 Safety glasses
• 🧰 Nitrile or mechanic’s gloves
• 🧰 Funnel (for ATF, if you choose to gravity-feed)
• 🧰 Small torque bit set for underbody shield fasteners (if equipped)

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🔩 Required Parts

HowToo sells all the parts you need for this repair:

• 🔩 Toyota WS automatic transmission fluid - Qty: 6–7 liters (for one drain-and-fill)
• 🔩 Transmission drain plug crush washer - Qty: 1
• 🔩 Transmission overflow tube plug crush washer - Qty: 1
• 🔩 Transmission refill plug crush washer - Qty: 1
• 🔩 Brake cleaner spray - Qty: 1–2 cans
• 🔩 Disposable shop towels - Qty: 1 pack
• 🔩 Replacement underbody splash shield clips - Qty: 4–6 (optional, in case some break)

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📋 Before You Begin

• Park the Highlander on a perfectly level surface. Engage the parking brake and place wheel chocks behind the rear wheels.
• Gather all tools and parts before lifting the vehicle. Prepping saves frustration later.
• Check that your scan tool can read Transmission Fluid Temperature (TFT). This is needed to set the final fluid level accurately.
• Plan disposal for old ATF. Use a sealed container and take it to a recycling center or shop that accepts used oil/ATF.
• Do this job with the transmission initially at room temperature, not fully hot. It’s safer and reduces burn risk.

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🔨 Step-by-Step Instructions

Follow these steps in order:

Step 1: Lift and Support the Highlander

• Use the floor jack to lift the front of the Highlander at the front central jack point (behind the front bumper, on the subframe area).
• Place jack stands under the left and right front pinch welds or frame points and lower the vehicle onto them.
• Lift the rear slightly and support with jack stands so the SUV sits level front-to-back.
• Verify stability by gently rocking the vehicle; it must not move.

Step 2: Remove the Underbody Splash Shield

• Identify the plastic splash shield under the engine and transmission.
• Use a 10mm socket and/or trim clip removal tool to remove bolts and plastic clips holding the shield.
• Lower the shield and set it aside.
• Keep bolts and clips in a tray so you don’t lose them.

Step 3: Locate Drain, Overflow, and Refill Plugs

• The drain plug is on the bottom of the transmission pan (center area).
• The overflow/level plug is a smaller plug (often inside or near the drain assembly) that uses a 6mm hex bit socket.
• The refill plug is on the side/front of the transmission case, higher up, usually using a regular hex head (commonly 14mm).
• Confirm each before loosening anything. Wrong plug can cause big problems.

Step 4: Loosen the Refill Plug First

• Position the drain pan under the transmission area just in case.
• Use a 14mm socket and ratchet to crack loose the refill plug on the side of the case, but do not remove it yet.
• This ensures you can refill after draining. If it’s stuck or damaged, you must not proceed with draining.

Step 5: Remove the Drain Plug and Let Fluid Drain

• Place the drain pan directly under the transmission drain plug.
• Use the correct socket (typically 14mm) to remove the main drain plug slowly.
• Allow fluid to drain completely. This may take 10–15 minutes.
• Measure how much drains into a marked container; this gives you a refill ballpark.

Step 6: Remove the Overflow Tube Plug

• With the main drain plug area open and most fluid out, use a 6mm hex bit socket to remove the smaller overflow/level plug (inside the drain assembly or adjacent, depending on exact design).
• Some additional fluid will drain when this tube is removed—let it finish.
• Inspect the overflow plug and its crush washer for damage or deformation.

Step 7: Reinstall Overflow Tube and Drain Plug

• Install a new crush washer on the overflow plug.
• Use the 6mm hex bit socket to reinstall the overflow/level plug and tighten to 20 Nm (15 ft-lb).
• Install a new crush washer on the main drain plug.
• Use the appropriate socket and torque wrench to tighten the drain plug to 49 Nm (36 ft-lb).
• Clean the area with brake cleaner and shop rags so any future leaks are easy to spot.

Step 8: Initial Refill of New Fluid

• Remove the refill plug fully using a 14mm socket.
• Connect the fluid transfer pump hose snugly into the refill opening.
• Pump in fresh Toyota WS ATF. Start by adding approximately the same amount that drained out (usually around 3.5–4.5 liters).
• Do not reinstall the refill plug yet; you will temporarily reinstall it loosely in the next steps.

Step 9: Temporary Reinstall Refill Plug and Start Engine

• Install a new crush washer on the refill plug.
• Use the 14mm socket to snug the refill plug (doesn’t need final torque yet).
• Lower the Highlander just enough so it’s still level but safe to run (you can leave it on stands if it’s rock-solid and level).
• Start the engine with the transmission in P (Park) and foot on the brake.

Step 10: Warm Transmission and Cycle Through Gears

• Connect your OBD2 scan tool to the diagnostic port under the dash.
• On the scan tool, view live data for Transmission Fluid Temperature.
• With your foot on the brake, move the gear selector slowly through R, N, D, S and back to P, pausing 2–3 seconds in each position. Repeat this 2–3 times.
• This fills all the internal passages with new fluid and equalizes levels.

Step 11: Set Correct Fluid Level at Specific Temperature

• Allow the vehicle to idle until the transmission fluid reaches about 40°C–45°C (104°F–113°F) on your scan tool. This is the Toyota level-check range.
• With engine idling in Park, carefully raise the vehicle back up safely on jack stands if needed, making sure it is perfectly level.
• With the engine still idling, place the drain pan under the transmission.
• Use the 6mm hex bit socket to remove the overflow/level plug again.
• Watch the fluid behavior from the overflow port:
  • If a steady stream comes out and then slows to a thin drip, let it drip until it’s just a slow drip, then go to Step 12.
  • If no fluid comes out, immediately reinstall the overflow plug loosely and go to Step 12 to add more fluid.

Step 12: Fine-Tune Fluid Level

• If no fluid came out at 40–45°C:
  • Reinstall the overflow plug loosely with the 6mm hex bit socket.
  • Stop the engine.
  • Remove the refill plug with the 14mm socket and pump in about 0.5 liter of ATF.
  • Reinstall refill plug snugly, restart the engine, and re-check at 40–45°C by opening the overflow plug again.
• Once you achieve a small, steady drip from the overflow port at 40–45°C with engine idling in Park, the fluid level is correct.
• Use the 6mm hex bit socket and torque wrench to tighten the overflow plug to 20 Nm (15 ft-lb) while the engine is still running.

Step 13: Final Tightening of Refill Plug

• Shut off the engine once the overflow plug is torqued.
• Use the 14mm socket to torque the refill plug to 39 Nm (29 ft-lb).
• Clean the entire area around drain, overflow, and refill plugs using brake cleaner and shop rags.

Step 14: Reinstall Underbody Shield

• Lift the splash shield back into place.
• Install all bolts with the 10mm socket and any clips using the trim clip removal tool to press them in if needed.
• Ensure the shield is secure on all sides.

Step 15: Lower Vehicle and Road-Test

• Use the floor jack to raise the SUV slightly and remove all jack stands, then lower it to the ground.
• Start the engine, shift through all gears briefly, then drive gently for 10–15 minutes.
• Check for any warning lights and listen for abnormal noises.

Step 16: Final Leak Check

• After the test drive, park on a level surface, set the parking brake, and let things cool slightly.
• Look under the Highlander for any drips around the transmission area.
• Inspect the drain, overflow, and refill plug areas again with a light to confirm everything is dry.

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✅ After Repair

• Check for transmission warning lights or messages on the dash over the next few drives.
• Pay attention to shift quality. It should feel smooth and consistent; any harsh shifts or slipping should be checked immediately.
• After a few days, look under the Highlander again for any signs of leaks.
• Keep a note of the mileage and date of this service for your maintenance records.
• Dispose of used ATF at a proper recycling facility or service station that accepts waste oil.

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💰 DIY vs Shop Cost

Shop Cost: $250–$450 (parts + labor)

DIY Cost: $80–$150 (fluid, washers, cleaner, small supplies)

You Save: $170–$300 by doing it yourself!

Shop labor rates vary but typically run $100–$150/hour. This repair takes a shop approximately 1.5–2.0 hours.

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