2007-2017 Lexus LS460 Power Steering Converter Failure: Diagnosis and Replacement Guide

Symptoms of a Failing LS460 Power Steering Converter

When the power steering converter begins to fail, the symptoms are often distinct and can appear intermittently. Recognizing them early can help you pinpoint the problem before it becomes a constant issue.

• "P/S" Warning Light: The most common sign is the illumination of the red or yellow "P/S" (Power Steering) warning light on your instrument cluster. This is often accompanied by a message on the multi-information display that reads, "Check Power Steering System – Take to Dealer Immediately."
• Sudden Loss of Power Steering: The steering wheel will become extremely heavy and difficult to turn, especially at low speeds or when parking. This failure can be abrupt, happening without any prior warning.
• Intermittent Operation: Many owners report that the problem is intermittent. The power steering might fail upon starting the car, only to begin working again minutes later or on the next drive cycle. Restarting the vehicle can sometimes temporarily restore function.
• Issues After Rain or Washing: Some failures are linked to moisture. The power steering may act up after driving through heavy rain, puddles, or after a car wash, suggesting water may be getting into a sensitive electrical connector in the system.
• Diagnostic Trouble Code U0131: A professional scan tool may reveal the code U0131, which means "Lost Communication with Power Steering Control Module." This indicates an electrical fault within the EPS system, which can be caused by a faulty converter.

Diagnosing the Power Steering System

Because the EPS system has multiple components (the rack motor, the main ECU, and the converter), diagnosis can be tricky. A failure in one part can present symptoms similar to another.

1. Check the Battery: As mentioned, always start with the simplest solution. Ensure your battery is fully charged and in good health.
2. Inspect Connectors: If you are comfortable doing so, inspect the electrical connectors on the steering rack and the power steering modules for corrosion or moisture. A poor connection is a known cause of intermittent faults.
3. Scan for Codes: Use an OBD-II scanner capable of reading manufacturer-specific codes to check for any stored trouble codes in the EPS module. Code U0131 points towards a communication breakdown that could be caused by the converter.
4. Component Isolation: For a professional technician, the next step is to test for power at the converter and from the converter to the main EPS module. If 12V is going into the converter but the correct output voltage is not coming out, the converter is the likely culprit.

Buying a Used Power Converter

Since new aftermarket options are not readily available for this specific part, a used OEM converter is a cost-effective and reliable choice. Here’s what to look for when buying a recycled part.

• Verify the Part Number: The correct OEM part number for the 2007-2017 Lexus LS460 is G9250-50010. This number should be clearly visible on the part's label. This single part number covers the entire 2007-2017 model year range.
• Inspect the Connectors: This is the most critical inspection point. Look closely at the electrical connector sockets and pins. Avoid any unit that shows signs of green or white corrosion, bent pins, or melted plastic. A clean connector is essential for proper function.
• Check the Casing: Examine the aluminum housing for any signs of physical damage, such as cracks or heavy corrosion. While some surface corrosion on the steel mounting bracket is common and acceptable, the main housing should be intact.
• Buy from a Reputable Source: Purchase from an auto recycler that offers a warranty. A 60-day or longer warranty gives you peace of mind and protection against receiving a defective part.

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

While there are no specific recalls or TSBs for the G9250-50010 power converter itself, there is a relevant recall for the broader EPS system.

• NHTSA Recall 10V218000: This safety recall was issued for certain 2009-2010 Lexus LS460 models equipped with Variable Gear Ratio Steering (VGRS). The issue was with the main Steering Control ECU, which could cause the steering wheel to become off-center. The fix was to replace the ECU, not the converter. You can check if a vehicle was part of this recall by entering its VIN on the NHTSA website.

Replacement Guide

Replacing the power steering converter is a moderately difficult job that a skilled DIY mechanic can perform. It does not require any special programming after installation.

• Location: The power steering converter is located in the engine bay, underneath the battery and battery tray.
• Estimated Time: 1.5 - 2.5 hours.
• Difficulty: 3 out of 5.

General Steps:

1. Disconnect the Battery: Always disconnect the negative battery terminal first.
2. Remove Cowl and Covers: Remove the plastic engine covers and the cowl top ventilator louver to gain access to the battery area.
3. Remove Battery and Tray: Remove the battery hold-down, terminals, and the battery itself. Then, unbolt and remove the battery tray to expose the converter underneath.
4. Disconnect and Remove Converter: The converter is held in by a few bolts. Disconnect the two large electrical connectors and remove the bolts. The unit can then be lifted out.
5. Installation: Installation is the reverse of removal. Ensure the electrical connectors click securely into place. Reconnect the battery (positive terminal first, then negative).

Cost Comparison

The cost to replace a power steering converter can vary significantly depending on whether you use new or used parts and who performs the labor.

Frequently Asked Questions (FAQ)