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Inconsistent Brake Pedal Feel on 2019 RLX Sport Hybrid - Regenerative Braking Issues?

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Mike T. · rep 0 · May 26, 3:57 AM · 1 replies · solved · Question

Vehicle: 2019 Acura RLX Sport Hybrid Advance

Hello everyone,

I've been noticing some really inconsistent brake pedal feel in my 2019 Acura RLX Sport Hybrid Advance. Sometimes the pedal feels soft and requires a lot of travel to get good stopping power, while other times it's overly grabby, even with light pressure. It's making smooth stops difficult.

I suspect it might be related to the regenerative braking system, as the car transitions from regenerative to friction braking. It's particularly noticeable in stop-and-go traffic. There are no warning lights on the dash, and the fluid level looks fine. The car has about 45,000 miles.

Has anyone with a Sport Hybrid RLX experienced this kind of inconsistent brake pedal feel? Is this a known characteristic, or could something be wrong with the braking system or the hybrid's regenerative braking integration?

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 26, 3:57 AM

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ClearTheCode admin answer:

Inconsistent brake pedal feel on a hybrid vehicle like your 2019 Acura RLX Sport Hybrid Advance is often attributed to the complex interplay between the regenerative braking system and the conventional friction brakes. However, significant or sudden changes in pedal feel warrant investigation.

Common Causes & Diagnostics:

  1. Regenerative Braking System Calibration: The transition from regenerative braking (using the electric motors to slow the car and recharge the battery) to friction braking (using pads and rotors) needs to be seamless. Any glitch in this transition can lead to an inconsistent pedal feel. This could be a software issue or a sensor malfunction.
  2. Brake Fluid Contamination/Air: Even with a proper fluid level, contaminated fluid or air in the brake lines can cause a spongy or inconsistent pedal.
  3. Brake Pedal Position Sensor: This sensor tells the car how much brake pedal input you're applying. A faulty sensor could send incorrect signals, leading to erratic braking. This might trigger codes like C1880 (Brake Pedal Stroke Sensor Malfunction).
  4. ABS/VSA Modulator Issues: The ABS/VSA system manages brake pressure. A fault in this complex unit, or its associated sensors, can affect pedal feel. Codes such as C1860 (Brake Fluid Pressure Sensor Malfunction) could indicate an issue here.
  5. Worn Brake Components (Less Likely): While less likely to cause inconsistent feel without other symptoms (like grinding or pulsation), worn pads, rotors, or sticky calipers can contribute.

What to Do:

  1. Scan for Codes: Even without a dash light, have the vehicle scanned for pending or historical codes, particularly C-codes (Chassis codes) related to the braking system.
  2. Brake Fluid Flush: If the fluid hasn't been changed recently, consider a brake fluid flush with genuine Acura fluid. This can remove moisture and contaminants.
  3. Professional Diagnosis: Due to the integrated nature of the hybrid braking system, it's highly recommended to have an Acura dealership or a specialist shop diagnose the issue. They have the advanced diagnostic tools to check the regenerative braking system, brake pedal sensors, and ABS/VSA modulator. This is not a system to DIY troubleshoot, as brake system integrity is paramount for safety. Describe the specific conditions when the inconsistency occurs to aid in diagnosis.
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