2018 INFINITI Q50 Direct Adaptive Steering (DAS) Module: A Deep Dive

Understanding the 2018 Q50's Unique Steering System

The 2018 INFINITI Q50 equipped with Direct Adaptive Steering (DAS) does not use a conventional power steering system. It is a fully electronic, 'steer-by-wire' system. This is a critical point for anyone diagnosing issues or replacing parts. The system relies on a network of three separate control modules that constantly cross-check each other for safety and accuracy.

• DAST 1 - Steering Angle Main Control Module: This is the primary module discussed in this guide, typically located under the hood.
• DAST 2 - Steering Angle Sub Control Module: A secondary, redundant module.
• EPS/DAST 3 - Steering Force Control Module: A third module that helps manage steering effort and feedback.

When one of these modules fails, or if the system loses power, a clutch engages a mechanical steering shaft as a fail-safe. This results in very heavy, unassisted steering and is a primary indicator of a system fault.

Symptoms of a Failing DAS Control Module

Failure in the DAS system can present in several ways, not always as a complete loss of assistance.

• Heavy or Stiff Steering: This is the most common symptom. It occurs when the system enters its fail-safe mode, engaging the manual steering linkage. This can happen due to a module failure, sensor issue, or even a low battery at startup.
• Power Steering Warning Light: A dedicated warning light or message will appear on the dashboard indicating a fault in the steering system.
• Steering Wheel Pulls to One Side: Some owners report the steering wheel pulling hard to one side on its own, particularly after starting the car.
• Lack of Steering Responsiveness: The vehicle may not respond as expected to steering inputs, or the turning radius might feel different than usual. This was the subject of earlier model year recalls.
• "Charging System Malfunction" Warning: On Q50s with the 3.0L twin-turbo V6, a sudden loss of power steering accompanied by a charging system warning often points to a shredded serpentine belt, not a module failure. A misaligned A/C compressor pulley is a known issue that destroys the belt, which runs both the alternator and power steering.

Known Issues, Recalls, and Technical Service Bulletins (TSBs)

While most steering-related recalls targeted earlier 2014-2016 models for software issues, the technology shares common traits. For the 2018 model year and similar vehicles, these are the most relevant issues:

• TSB ITB17-040: Addresses the 3.0L V6 engine shredding its serpentine belt due to a misaligned A/C compressor. This causes an immediate loss of power steering and alternator function. The fix requires installing a special shim kit to realign the compressor pulley.
• TSB ITB20-043: For 2017-2020 Q50s, some owners complained of steering that felt overly light or sensitive. This is addressed by reprogramming the power steering control module with updated software.
• Early Model Recalls (e.g., 16V-430): Recalls on 2014-2016 models involved reprogramming the DAS electronic control unit to fix a software bug that could cause a lack of steering responsiveness right after starting the vehicle. This highlights the system's reliance on correct software.

Buying a Used Power Steering Control Module

Purchasing a used DAS module can offer significant savings, but it requires careful attention to detail. Given that a new OEM module costs over $1,600, a used part for a few hundred dollars is an attractive option.

1. Verify the Part Number EXACTLY

The most critical step is to match the part number on your original module to the letter. Remove the old unit first to confirm the number. Part numbers like 28505-4HK1C and 28505-4HK5C may look similar but are not interchangeable. Using the wrong module will prevent the system from being programmed correctly.

2. Factor in Programming Costs

This is not a plug-and-play part. A used module is essentially a blank slate that must be configured to your car. This procedure requires the INFINITI CONSULT III plus diagnostic tool and software subscription. You must have a budget for this service, which can only be performed by an INFINITI dealer or a high-level independent specialist shop with the proper equipment. Expect to pay several hundred dollars for programming and calibration.

3. Physical Inspection

When your used module arrives, inspect it carefully before installation:

• Check for Corrosion: Look at the pins in the electrical connectors. Any green or white crust is a sign of water damage, and the module should be returned.
• Inspect the Case: Check for cracks, deep gouges, or signs that the case has been pried open. This could indicate a failed repair attempt.
• Verify Connectors: Ensure none of the plastic connector housings are cracked or broken.

Replacement Cost Comparison

The cost of replacing the main DAS module varies dramatically based on the part source.

Note: Labor costs are an estimate. The complex programming and calibration procedure is the primary labor expense, often exceeding the cost of a simple mechanical replacement.

Programming and Calibration Requirements

Replacing any of the three DAS control modules is a two-part process: physical installation and electronic configuration. This is not a DIY-friendly job for the home mechanic.

1. Installation: The main module is located under the hood and is mechanically straightforward to replace for a technician.
2. Programming/Configuration: A technician must connect the INFINITI CONSULT III plus tool to the vehicle.
3. Configuration: The new module's software must be configured to match the vehicle's VIN and options.
4. Synchronization: All three DAS modules (DAST 1, DAST 2, and EPS/DAST 3) must be synchronized to communicate with each other.
5. Calibration: Finally, procedures like steering angle sensor neutral position adjustment must be performed.

Frequently Asked Questions (FAQ)