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SH-AWD System Malfunction Light On - 2018 RLX Sport Hybrid

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Mike T. · rep 0 · May 26, 3:33 AM · 1 replies · solved · Question

Vehicle: 2018 Acura RLX Sport Hybrid

I'm having an issue with my 2018 Acura RLX Sport Hybrid. The 'SH-AWD System Malfunction' light recently came on in my dashboard. There's no noticeable change in how the car drives, but the warning is definitely there and it's making me nervous.

I checked the tire pressure, and everything seems fine. I haven't hit any major potholes or had any work done on the car recently that would explain this. It just appeared out of nowhere during my drive home yesterday.

Has anyone encountered this warning on their RLX Sport Hybrid? What could be causing it, and is it safe to drive?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 26, 3:33 AM

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ClearTheCode admin answer:

An 'SH-AWD System Malfunction' warning on your 2018 Acura RLX Sport Hybrid indicates an issue within the Super Handling All-Wheel Drive system. While you might not feel an immediate difference, it's crucial to address it.

Potential Causes:

  1. Wheel Speed Sensors: These sensors monitor the rotation speed of each wheel. If one is dirty, damaged, or faulty, it can send incorrect data to the SH-AWD control unit, triggering a fault. This is a very common cause for AWD/ABS system warnings.
  2. SH-AWD Control Module: The dedicated control module for the SH-AWD system could be experiencing an internal fault or a communication error with other vehicle systems.
  3. Wiring Issues: Damaged or corroded wiring harnesses connected to the SH-AWD components (like the rear differential's electric motors or sensors) can interrupt signals and cause a malfunction.
  4. Rear Differential Actuators/Motors: The Sport Hybrid's SH-AWD system uses electric motors on the rear axle to provide torque vectoring. A fault in one of these motors or its associated components could trigger the warning.
  5. Low Battery Voltage: Sometimes, a weak 12V battery can cause various electronic warnings, including SH-AWD, due to insufficient power to modules.

Common OBD Codes: While an OBD-II scanner might show generic powertrain codes, a more advanced scanner is needed for chassis-specific codes. You might see codes like C1800 (generic SH-AWD fault) or more specific codes related to individual wheel speed sensors or torque vectoring components.

When to See a Shop:

  • Immediately: While the car might seem to drive normally, the SH-AWD system is a critical safety and performance feature. Driving with a malfunction could mean you lose the benefits of torque vectoring and enhanced traction, especially in adverse conditions.
  • A professional diagnosis using Acura-specific diagnostic tools is necessary to pinpoint the exact cause. They can read the specific fault codes from the SH-AWD module and perform tests on the system's components. Do not delay seeking professional help for this warning.
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