lillybrown87
GS Hybrid brake pedal feedback
Summary of the thread
The initial concern was unusual feedback from the brake pedal in a 2006 Lexus GS hybrid. The issue was suspected to be related to the brake booster or possibly the hybrid system's regenerative braking. It was suggested that undervoltage could affect the brake-by-wire system, particularly if the 12V battery was old or failing. Testing the battery voltage with a multimeter confirmed the problem, and replacing the battery resolved the issue, restoring normal brake function.
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4 comment(s)
lillybrown87 (community.author)
Hmm, undervoltage is interesting. I did have to jump it a few weeks ago, now that you mention it. So, what exactly happens with the brake system when there's undervoltage? And is there a way to test for that?
ella_schulz7
Undervoltage can really throw off the ECU and cause unpredictable behavior in the brake actuator assembly. This system blends regenerative and hydraulic braking. If the voltage is low, the actuator might not function correctly, causing the strange pedal feel you're experiencing. A multimeter will easily show you the battery's voltage. If it's consistently below 12.6V when the car is off, you need a new battery. It's worth a trip to a workshop, just to be sure.
lillybrown87 (community.author)
Thanks a ton for the insight! Took it to a shop, and it turned out to be exactly what you said – undervoltage causing issues with the brake actuator. New battery and a system reset fixed it! Cost me 240€. Appreciate the help!
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LEXUS
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GS
ella_schulz7
Strange brake pedal feel on a GS hybrid could point to a few things. The hybrid system uses regenerative braking, so undervoltage can mess with the whole brake-by-wire setup. Have you noticed any other electrical issues, like flickering lights or slow starting? How old is your 12V battery?