Chrysler 300 Diesel: Spongy Brake Pedal Warning Signs

I had a similar issue with my 2006 Chrysler Sebring diesel last year. Having some experience with basic car maintenance, I initially thought it was related to the brake system too, particularly the brake pads or brake rotors. However, after taking it to the workshop, they diagnosed an undervoltage problem affecting multiple systems, including the brake assist. The main symptoms matched yours exactly, spongy brake pedal, vibrations, and needing more pressure than usual. The workshop found that the alternator wasnt delivering consistent voltage, which affected the brake assist system. The total repair cost was 240€, including diagnostic time and parts replacement. Before jumping to conclusions about your brake system, it would help to know: Are there any warning lights on the dashboard? Have you noticed dimming headlights or other electrical issues? Does the problem occur more when the engine is cold or warm? Are there any unusual sounds when applying the brakes? While brake fluid levels might look normal, its worth checking if the brake rotors and brake pads are within spec, but based on my experience, getting the electrical system checked might save you from unnecessary brake work.

Thanks for sharing your experience. My vehicle has about 20326 KM and shows no warning lights on the dashboard. After reading your response, I checked and noticed the headlights do seem slightly dimmer than usual, especially at idle. The brake pedal feels most spongy when the engine is warm, and there is a slight grinding noise when braking. Given these symptoms and your experience, I will have both the electrical system and brake components checked. While the brake calipers and brake shoes were serviced recently, an electrical issue affecting the brake assist would explain the inconsistent pedal feel. Will update once I get it diagnosed.

Thanks for the update, those additional symptoms definitely align with what I experienced. The grinding noise is a new variable though, which I didnt have with my Sebring. That could indicate we might be dealing with two separate issues here. The dimming headlights combined with the spongy brake pedal strongly points to the electrical system affecting the brake assist, just like in my case. However, that grinding noise when applying the brakes suggests there might also be some wear on your brake components. My mechanic explained that when the brake assist system isnt working properly due to electrical issues, it can actually accelerate wear on the brake pads and disc brakes since youre having to apply more pressure. I ended up having both the alternator replaced and getting new brake pads installed, since the extra pressure I was applying had worn them down faster than normal. The squeaky brakes and grinding completely disappeared after addressing both issues. Would definitely get it checked soon, trying to compensate for reduced brake assist can create a cycle of increased wear on your brake system components. Keep us posted on what the diagnosis reveals.

Thank you for sharing these details. The dimming headlights combined with the brake pedal issues do suggest potential electrical problems. Just had the car checked today at the repair shop. The technician found two issues: a failing alternator causing inconsistent voltage to the brake assist system, and worn brake rotors that needed replacement. The grinding noise was indeed coming from the brake system where one of the brake calipers was sticking slightly due to the inconsistent power supply. Total repair costs came to 780€, which included: New alternator and installation, Brake rotor replacement, One new brake caliper, Fresh brake fluid flush The brake pedal now feels firm and responsive, headlights are back to full brightness, and the grinding noise is completely gone. While it was more expensive than expected, having both issues fixed at once probably prevented further damage to the brake system components. Thanks again for pointing me in the right direction with the electrical system check. It saved time in diagnosing the root cause of the problems.