2004-2006 Scion xA Front Knee & Knuckle: A Guide to Production Dates and ABS Variants

Symptoms of a Failing Front Knee Assembly

Problems with the front knee assembly typically originate from one of its core components: the wheel bearing, the ball joint, or the knuckle itself. Each has distinct warning signs.

1. Humming, Roaring, or Grinding Noises

This is the classic sign of a worn-out wheel bearing. The noise is often described as a hum or roar that starts faint and gets progressively louder. It is directly related to vehicle speed — the faster you go, the louder it gets. A key diagnostic clue is that the sound may change in pitch or intensity when you turn the steering wheel slightly left or right on the highway; typically, the noise will get louder when turning away from the bad bearing (e.g., turning left loads the right wheel bearing).

2. Clunking or Knocking Over Bumps

A sharp clunking or popping sound when driving over bumps, dips, or uneven pavement often points to a worn lower ball joint, which connects the bottom of the steering knuckle to the lower control arm. This indicates excessive play in the joint, which can affect steering stability. Similar noises can also be caused by worn sway bar links or strut mounts, so a full front-end inspection is necessary.

3. Steering Wheel Vibration or Pulling

A vibration felt in the steering wheel that changes with speed can be another symptom of a bad wheel bearing. More severe, however, is a bent steering knuckle. This typically only happens after a significant impact, such as hitting a curb, a deep pothole, or being in an accident. A bent knuckle can cause the vehicle to pull to one side and may make a proper wheel alignment impossible, leading to rapid and uneven tire wear.

4. ABS Warning Light

On models equipped with an Anti-lock Braking System (ABS), the wheel speed sensor is mounted on the steering knuckle. A failing wheel bearing can sometimes damage this sensor or the tone ring it reads, triggering the ABS light on your dashboard.

Known Issues, Recalls, and Part Variants

The Scion xA shares its platform with the Toyota Echo and first-generation Scion xB, so many suspension parts are interchangeable. However, several mid-generation changes create compatibility challenges for the 2004-2006 xA.

Production Date Splits

Toyota made changes to the front suspension during the xA's production run. The two most important dates to be aware of are May 2003 and October 2004. Parts like the lower control arms are different for vehicles built before and after these dates. You can find your vehicle's specific production month and year on the sticker inside the driver's side door jamb.

• Early 2004 Models (Built before 05/2003): These very early production models may use different lower control arms. For example, the right-side lower control arm for this period is part number 48068-59035.
• Mid-Production Models (Built 05/2003 - 09/2004): These vehicles use a different set of parts.
• Late Production Models (Built from 10/2004 - 2006): Another part change occurred for the 2005 model year refresh.

ABS vs. Non-ABS Knuckles

The steering knuckles are different for cars with and without an Anti-lock Braking System (ABS). The ABS-equipped knuckle has a mounting hole for the wheel speed sensor. A non-ABS knuckle lacks this provision. It is physically impossible to install an ABS sensor on a non-ABS knuckle. The easiest way to check is to look behind your current wheel assembly; if you see an electrical wire running to the knuckle, your car has ABS.

Buying a Used Knee, Front: What to Inspect

A used OEM knee assembly can be an excellent value, often saving you hundreds in parts and labor compared to replacing individual components. Because the wheel bearing is already pressed into the knuckle, it turns a difficult job requiring a shop press into a much simpler bolt-on replacement. Here’s what to look for:

1. Verify the Source Vehicle: Get the VIN or, at minimum, the production date (month/year) and ABS status of the car the part came from. This is the single most important step.
2. Check for an ABS Port: If your car has ABS, ensure the used knuckle has the threaded hole for the wheel speed sensor. If buying online, confirm this with the seller and look for it in photos.
3. Inspect the Wheel Bearing: With the assembly on the ground, try to spin the wheel hub by hand. It should rotate smoothly and silently. If you hear any grinding or feel any roughness, the bearing is bad. Grab the hub and try to wiggle it; there should be zero play or looseness.
4. Examine the Ball Joint: If the assembly includes the lower control arm, inspect the rubber boot on the ball joint. It should be intact with no rips or tears. Squeeze it to feel for grease inside. A torn boot means the joint is contaminated and will fail soon.
5. Look for Impact Damage: Carefully inspect the entire knuckle for any cracks, bends, or signs of heavy impact. Check the mounting points for the strut, caliper, and tie rod to ensure they are not warped or damaged.

Cost of Replacement

Replacing the entire knee assembly is often more cost-effective than just replacing a pressed-in wheel bearing, especially when factoring in labor.

Related Parts to Consider Replacing

When replacing the front knee assembly, several other components are disconnected. It's a good time to inspect and, if necessary, replace them.

• Outer Tie Rod End: Connects the knuckle to the steering rack. Check for play.
• Lower Control Arm: If not replacing it with the assembly, inspect the bushings for cracks or wear.
• CV Axle Nut: This is a one-time use nut and should always be replaced with a new one.
• Sway Bar Link: These are often removed for access and can have worn bushings causing clunking noises.

Frequently Asked Questions (FAQ)

Technical Specifications & Procedures

Key Torque Specifications

Using a calibrated torque wrench is critical for safety and performance. Do not guess or use an impact wrench on these components.

Verified OEM Part Numbers

This list is a starting point. Always verify fitment using the vehicle's VIN and production date.

• Steering Knuckle, Front Right (w/ ABS): 43211-52020
• Steering Knuckle, Front Left (w/ ABS): 43212-52020
• Lower Control Arm, Front Right (from 05/2003): 48068-59035
• Lower Control Arm, Front Left (from 05/2003): 48069-59065
• Front Wheel Hub: 43502-52010