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lexpert, Lexus Master tech
Category: Lexus
Satisfied Customers: 2100
Experience:  Master Certified with lexus, 8 years experience with Lexus
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I have an es 300 and the brake peddle is soft only when the

Customer Question

i have an es 300 and the brake peddle is soft only when the car is running. When i bleed the brakes the peddle is perfect after doing so. i start it and it is immediately soft again. this was after i replaced the master cylinder
Submitted: 1 year ago.
Category: Lexus
Expert:  Victor replied 1 year ago.

Hello and welcome to JustAnswer.

Did you bench bleed the master cylinder before installing it on the car?

Customer: replied 1 year ago.
we bench bleed the master. the brake peddle works perfect when the car is off and the brakes have been bleed. As soon as we start the car there is no brake peddle it will go to the floor. We checked all the fuses. Unrelated to this problem we did replace the battery because the battery had 2 dead cells.
Expert:  Victor replied 1 year ago.

If all air is out of the master cylinder and still have a soft pedal, then you have air trapped in the abs unit. Did you used a scan tool to activate each solenoid inside the abs pump?

Customer: replied 1 year ago.
I do not have a lexus / toyota scan tool. i do have a snapon GM/Chrisler/ GMC one... Does this can tool connect through the OBD or directly into the ABS unit? Can i rent one from the auto parts store?
Expert:  Victor replied 1 year ago.

Yes, the connection is direct to the OBD diagnostic connector. I am not 100% sure the auto parts scan tool will work as I have never used them. I always had access to the dealers scan tool when I work there. Some scan tools they use are just code reading only with no active testing. You will have to ask them if the scan tool they use have access to active test the abs system.