D35tr0y312

Hi everyone, I have a 99 GS400 with 200k mile on it. Recently i have been getting a BRAKE, VSC, ABS,VSC OFF, and loud buzzing noise. So the brake booster pump sound good when it runs but sometimes it will run for 5 mins and then the alarms. While the alarms are in Im still able to brake and the car coast to a stop just fine. I don't have soft pedal or pedal to the floor. the codes i have seen are C1252, C1223, several times along with other codes that were self generated during troubleshooting.
> previous owner says its the oil level. I ohmed it out and it is open when full and close when empty. i even disconnected the wire connection and still got the alarms during a drive test
> There are two pressure switches on the ASIN black box and they were opening and closing when I tested it. low pressure switch was 1000ohm= close and 4700ohm=open. the hi pressure switch 1ohm=close and 1000ohm=open.
>the only thing i have not tested is the accumulator. My questions on that are, what is the precharge pressure and can it be recharge, can i unscrew it out without removing the entire assembly, what are the pressure set points on the two pressure switches?
Any other info and resources would be much appreciated. thank you