2015-2020 Acura TLX Rear Toe Control Module: P-AWS Failures, Warnings, and Replacement Guide
This guide covers the common failures, diagnostic codes, compatibility warnings, and essential programming steps for the Rear Toe Control Module in 2015-2020 Acura TLX models with the 2.4L engine.
- This module is ONLY for 2015-2020 Acura TLX models with the 2.4L engine and Front-Wheel Drive (FWD).
- A replacement module, whether new or used, will require programming/initialization by a dealer or a qualified shop with Honda-specific software.
- Failure often triggers a cascade of other warning lights, including VSA, collision mitigation, and lane departure systems.
- Before replacing the module, have the related P-AWS actuators and wiring checked, as TSB 15-050 points to actuator connector issues.
Compatibility Warning: 2.4L FWD Models Only
Crucial: This Rear Toe Control Module (part numbers 39300-TZ4-A01, 39300-TZ4-A02) is only compatible with 2015-2020 Acura TLX models equipped with the 2.4L four-cylinder engine and Front-Wheel Drive (FWD). It will NOT work on V6 models or any model with Super Handling All-Wheel Drive (SH-AWD), as they use a completely different rear suspension and drivetrain setup.
Known Issues, TSBs, and Warranty Extensions
Acura has acknowledged several issues related to the P-AWS system in the 2015 TLX. While no formal recalls have been issued for the control module itself, several Technical Service Bulletins (TSBs) and a warranty extension address related components.
- TSB 15-050: Released in November 2015, this bulletin addresses an issue where multiple warning lights appear on the dash along with Diagnostic Trouble Code (DTC) U129D (F-CAN malfunction). The cause was identified as a bad wire crimp in the rear toe control actuator connector. The corrective action is to replace both rear toe control actuators.
- Warranty Extension for RTC Actuators: Acura extended the warranty on the rear toe control (RTC) actuators to 10 years with no mileage limit for certain TLX and RLX models. This was in response to manufacturing errors causing abnormal noise from the rear and/or DTCs C1600-94, C1611-13, or C1621-13. While this doesn't cover the module, it's important to know if you are diagnosing a P-AWS system failure.
Symptoms of a Failing Rear Toe Control Module
Failure of the P-AWS control module or its related components will typically trigger a cascade of warning lights on the instrument panel, as various safety systems rely on its input.
- P-AWS System Warning Light: The most direct symptom is an amber warning light or message on the dash indicating a problem with the Precision All-Wheel Steer system. 🎬 Watch: How Acura's P-AWS system works
- Multiple Warning Lights: Owners report that a P-AWS failure often triggers lights for Vehicle Stability Assist (VSA), Forward Collision Warning, and Lane Departure Warning simultaneously.
- Limp Mode: In some cases, the vehicle may enter a "limp mode," limiting the top speed to around 50 mph as a safety precaution.
- Changes in Handling: While the system is designed to default to a safe, fixed rear toe angle, some drivers may notice less stability at highway speeds or a wider turning circle at low speeds.
- Diagnostic Trouble Codes (DTCs): A professional scan tool may reveal specific codes stored in the system. Common codes include U129D (F-CAN malfunction), C1600-94 (PAWS unexpected behavior), and codes related to the actuator circuits like C1621-13. A diagnostic video for a 2015 TLX also pointed to codes 85-15 and 85-12, which led to further investigation of the P-AWS module. 🎬 See: 2015 TLX rear steering diagnostic and fix
Pro Tip: Before condemning the module, check the battery and charging system. Low voltage from a weak battery or failing alternator can cause multiple, seemingly unrelated electronic modules to throw error codes on modern Acura vehicles.
Buying a Used Rear Toe Control Module
A used OEM module is an excellent, cost-effective alternative to a brand-new unit. Because this is a complex electronic part, a recycled original part is often more reliable than a new, unproven aftermarket version. Here’s what to look for:
- Verify the Part Number: Match the part number on your original module to the replacement. The primary numbers are 39300-TZ4-A01 and 39300-TZ4-A02. The '-A02' version is a later revision and replaces the '-A01' part.
- Check for Physical Damage: The module is located in the cabin, typically in the driver's side kick panel area, protecting it from the elements. However, inspect the replacement unit's casing for any cracks and ensure all connector pins are straight and free of corrosion.
- Source from a Reputable Seller: Purchase from a seller who offers a warranty and has good reviews. This provides protection in case the part is faulty. Some sellers may offer a 1-year warranty on used units.
Programming and Initialization
Warning: After installation, this module will likely require initialization or programming to function correctly with your vehicle. While many Honda/Acura modules come pre-programmed, system-critical modules like this often need to be initialized to the vehicle's other control units.
This is not a simple plug-and-play part. The procedure synchronizes the module with the vehicle's main computer and sensor inputs. While some high-end independent shops with professional scan tools (like Autel or Snap-on) may be able to perform the initialization, it often requires the dealer-specific Honda Diagnostic System (HDS) software. It is best to confirm with your chosen technician that they have the capability to initialize an Acura P-AWS module before purchasing the part.
Cost Breakdown
Prices can vary based on location, supplier, and part condition. Here is a general cost estimate:
| Part Type | Estimated Cost |
|---|---|
| New OEM | $635 - $1,100 |
| Used OEM | $40 - $210 |
| Shop Labor (Replacement & Programming) | $100 - $250 |
Frequently Asked Questions (FAQ)
Do I have to go to an Acura dealer to program a replacement module?
Not necessarily, but it's the safest bet. An Acura dealer will have the guaranteed correct software (Honda HDS) to initialize the module. Some well-equipped independent repair shops may also have this capability, but you must confirm with them first. A general mechanic or locksmith likely cannot perform this specific procedure.
Can I drive my TLX with a bad Rear Toe Control Module?
Yes, but with limitations. When the P-AWS system fails, it is designed to default to a neutral, fixed rear toe position, making the car safe to drive. However, you will lose the advanced handling benefits, and other safety systems like VSA may be disabled. If the car enters a "limp mode," your speed will be restricted, so you should drive directly to a repair facility.
Will a module from a TLX V6 or AWD model work?
No, absolutely not. This module is specifically for the 2.4L FWD model, which is the only TLX variant with the P-AWS system. V6 and SH-AWD models use different hardware and control systems.
Is the Rear Toe Control Module the same as the actuator?
No. The Rear Toe Control Module is the electronic computer that controls the system. The actuators are the mechanical/electrical parts mounted to the rear suspension that physically move the wheels. It is possible for the actuators to fail while the module is still good, and vice-versa.
Helpful Videos
Technical Specifications
OEM Part Numbers: 39300-TZ4-A0 39300-TZ4-A01 39300-TZ4-A02
Controls the Precision All-Wheel Steer (P-AWS) system on 2.4L FWD models. Located in the driver's side interior kick panel area.
We Have This Part in Stock
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Acura TLX: