2015 Toyota Highlander Transmission & Axle Gear Ratios

If you are researching the drivetrain specifications for a 2015 Toyota Highlander, understanding its transmission and axle gear ratios is crucial. Whether you are looking to tow a small boat, optimize your daily commute for better fuel economy, or diagnose a driveline whine, knowing exactly how your SUV translates engine power to the wheels can help you make informed decisions. Below is the comprehensive guide to the 2015 Toyota Highlander transmission and axle gear ratios.

Transmission gear ratios

The 2015 Toyota Highlander was offered with three main powertrains: a 2.7L 4-cylinder, a 3.5L V6, and a 3.5L V6 Hybrid. The traditional gas engines utilize 6-speed automatic transmissions, while the Hybrid utilizes an Electronically Controlled Continuously Variable Transmission (eCVT).

6-Speed Automatic (U760E) - 2.7L 4-Cylinder

Used exclusively in the base LE trim with the 2.7L 4-cylinder engine (FWD only).

6-Speed Automatic (U660E FWD / U660F AWD) - 3.5L V6

This is the most common transmission found in the 2015 Highlander, paired with the 3.5-liter V6 engine across LE Plus, XLE, Limited, and Limited Platinum trims.

Note: The Hybrid model utilizes an eCVT which does not have fixed, stepped forward gears.

Available axle ratios

Unlike trucks that offer multiple axle ratio options for the same engine to customize towing capacity, the 2015 Toyota Highlander's axle (final drive) ratios are strictly tied to the engine and drivetrain configuration from the factory.

How to identify your axle ratio

Identifying your specific axle ratio on a 2015 Toyota Highlander is relatively straightforward, though it differs slightly from domestic trucks that use RPO stickers or metal axle tags.

1. The Door-Jamb Sticker: Open the driver’s side door and look for the federal compliance sticker (often black and white or tire pressure placard area). Look for a string of text at the bottom that starts with C/TR/A/TM.
2. Decoding the String: The "A" stands for Axle. You will see a code like A/TM: -01A/U760E. The first part is the axle code, and the second part is the transmission code.
3. Using a VIN Decoder: Because the Highlander’s axle ratio is hard-coded to its engine, simply knowing whether you have the 2.7L, 3.5L, or Hybrid (which is tied to your VIN) will definitively tell you your final drive ratio. Simply inputting your VIN into a reliable Toyota VIN decoder will give you the exact factory specifications.

Towing vs MPG impact

The relationship between axle ratios, towing capacity, and fuel economy is a delicate balancing act. While the Highlander doesn't allow you to mix and match ratios, understanding how they work explains why Toyota engineered them this way.

Numerically higher ratios (e.g., 4.356, 4.154): A higher numeric ratio means the engine turns more times for every revolution of the tires. This multiplies engine torque, making it much easier to accelerate from a dead stop and vastly improving towing performance. The V6's 4.154 ratio combined with its power output allows the Highlander to tow up to 5,000 lbs properly equipped. The downside is that at highway speeds, the engine sits at a higher RPM, which can consume more fuel.

Numerically lower ratios (e.g., 3.542): A lower numeric ratio reduces engine RPM at cruising speeds, thereby saving fuel. The Hybrid model uses a 3.542 final drive ratio to maximize MPG, though it relies heavily on instant electric torque from the hybrid motors to maintain acceptable acceleration. Lower ratios generally reduce maximum towing capacity, which is why the Hybrid is rated to tow less (3,500 lbs) than the standard V6.

Common issues

The drivelines in the 2015 Toyota Highlander are generally considered highly reliable, but as mileage increases, a few common issues can emerge:

• AWD Viscous Coupling / Transfer Case Whine: On AWD models, a low-pitched whine or hum from the front transfer case or rear differential can indicate worn carrier bearings or fluid degradation. It is highly recommended to change the differential fluid every 30,000 to 60,000 miles, especially if you tow frequently.
• Transmission Shudder (U660E/F): Some owners report a mild shudder or delayed engagement in the 6-speed transmission at lower speeds. This is often rectified by a software update to the Transmission Control Module (TCM) or a fluid flush.
• Axle Seal Leaks: High-mileage Highlanders can develop weeping at the axle seals where the CV axles enter the transmission or rear differential. Keep an eye out for oily residue on the underside of the vehicle.

If you suspect your gear ratios are compromised by differential wear, or you need a routine fluid service to keep your SUV towing smoothly, professional help is just a click away.

Find a driveline shop on Repairius.