2016 Lexus RX350
Hello Scotty
Mechanic replaced rear rotors and pads. Said that Lexus procedures were followed. The car now shows the error “EPB activation stopped incompletely” when putting the car in park. It was originally diagnosed that the left side actuator is bad because you could hear it attempting to engage. To confirm the EPB actuators were switched from left to right . The left side was still not engaging properly. Therefore , it was recommended replacing the left caliper even though nothing was leaking and no apparent damage. I approved the new caliper and there was no change. The left actuator will not fully engage , causing the fault message in the cluster. The scan tool shows live data and shows that the left side is showing about 4-5 amps and the right side is “0”. Performing a complete scan there are 0 codes stored.
in an attempt to find out the problem it was discovered that when the brake pedal is applied it does not fault and works fine when putting it in park, but here is the rub , I have owned the car for 5+ years and have always applied the brake but now I have to press the Barbie peddle harder/more pressure. The mechanic connected a live scan tool to check the hydraulic PSI and discovered that in order for the EPB to work (not error) it requires a minimum of 110 PSI. Any thing less and it errors , more pressure works ok. I drove the car for about an hour with the scan tool connected and discovered that my normal driving habits when parking I applied around 65-75 PSI.
having said this , I believe that putting the car in park shouldn’t require applying the brake pedal for the auto EPB to function. Never gave it any thought in the past , I kept my foot on the brake pedal only because that’s how I use all manual parking brakes in attempt to not put a strain on the transmission. It’s a habit that I have done for 50 years ..
I asked if it could be the brake actuator in the engine bay but he said no because it’s not throwing codes. I asked about the master cylinder but he said no. I know it’s not the brake booster. the brakes otherwise work fine. Foot pedal feel is good, no pulling , etc..
An OEM actuator is 1200.00 each side and I have looked for aftermarket , which I never use, but even some of those are in the same price range, regardless, I don’t think that is the issue anyway.
Any guidance/info is appreciated. Almost 4 weeks and it still isn’t working properly.
Thank you
tim
Realize the rub with all that complex modern electronic nonsense when it breaks across the fortune to fix. Seems to me that the actuator itself is broken and no one's going to fix it. If it did happen right after the brake job then the brake job was done incorrectly. You have to have special tools to turn that system off and to retract the Pistons when you do the brake job and if you don't have that, something as dumb as even squeezing the Pistons back in can destroy the actuator.
