2005 Honda Accord Hybrid

I STARTED TO NOTICE THIS ISSUE MONTHS AFTER PURCHASING IT USED FROM A PRIVATE PARTY. DURING THE WINTER TIME WHEN IT WAS PARTICULARLY COLD OUTSIDE, I NOTICED THAT MY POWER BRAKES WOULD START WORKING WHEN I FIRST START UP THE CAR. EVENTUALLY, I WOULD DISCOVER THAT THE BRAKE BOOSTER CHECK VALVE WAS STICKING AND PREVENTING THE POWER BRAKES FROM BEING ACTIVE WHEN STARTING A VEHICLE IN THE COLD WEATHER. IT WAS VERY CONFUSING AT FIRST BECAUSE THERE WOULD BE STORED POWER BRAKES IN THE VACUUM BOOSTER FROM THE DAY BEFORE THAT WOULD BE USED UP WHEN BACKING OUT OF MY PARKING SPOT. HOWEVER, AS I WAS MOVING FORWARD AND SUBSEQUENTLY WANTING TO APPLY THE BRAKES, I FOUND THAT THE POWER BRAKES WERE NOT WORKING. THE BRAKE PEDAL BECAME HARD AND WOULD NOT GO DOWN AND I HAD TO JAM ON THE BRAKE PEDAL AS HARD AS I COULD TO GET IT TO SLOW DOWN. HOWEVER, ONCE THE CAR ENGINE HAD BEEN ON FOR A WHILE, I WOULD HEAR A CLICK NOISE (PROBABLY THE CHECK VALVE UNSTICKING) AND THEN POWER BRAKES WERE RESTORED FOR THE REST OF THE COMMUTE. I EVENTUALLY HAD THE BRAKE BOOSTER VACUUM HOSE REPLACED (WHICH ALSO CONTAINED THE CHECK VALVE) AND NO LONGER HAD THIS ISSUE. THE MECHANIC WHO REPLACED THE HOSE CONFIRMED THAT THE CHECK VALVE WAS FAULTY BECAUSE THE OLD HOSE WOULD NOT ALLOW AIR THROUGH WHEN THEY TRIED TO BLOW THROUGH IT FROM EITHER DIRECTION.

HAVE NOTED ON A FEW OCCASIONS THAT THE BRAKE BOOSTER IS NOT ACTIVATED WHEN A CAR HAS BEEN SITTING OVERNIGHT OR FOR EXTENDED DURATION OF TIME. WHAT TYPICALLY HAPPENS IS THAT I START THE VEHICLE AND SHIFT IT INTO GEAR AND PROCEED. HOWEVER, IF I HAVE TO BRAKE WITHIN 1-2 MINUTES OF STARTING THE CAR, THE BRAKE BOOSTER APPEARS TO NOT BE WORKING AND I AM LEFT USING MANUAL BRAKES ESSENTIALLY SINCE THE VACUUM BOOST IS NOT WORKING. ONCE THE CAR HAS BEEN RUNNING FOR A FEW MINUTES, THE BRAKE BOOSTER STARTS WORKING NORMALLY. BECAUSE OF THIS INTERMITTENT BEHAVIOR, I HAVE ALMOST CRASHED INTO THINGS WHILE BACKING UP OR DRIVING FORWARD SINCE THE POWER BRAKES WERE ESSENTIALLY NOT WORKING IN THOSE SCENARIOS. I HAVE CHECKED THE BRAKE BOOSTER SYSTEM AND EVERYTHING APPEARS TO BE NORMAL. BRAKE PEDAL DOES NOT SINK DURING NORMAL OPERATION, NOR DOES THERE APPEAR TO BE A LEAK IN THE BRAKE SYSTEM WHEN I PRIME/PUMP THE BRAKE WHILE THE CAR IS TURNED OFF. AFTER INVESTIGATING THE ISSUE, I HAVE FOUND A TEMPORARY SOLUTION IS TO START THE CAR AND PUMP THE BRAKES FIRST BEFORE GOING. THE BRAKES WILL LOSE THE VACUUM BOOST IN THE INITIAL 2-3 PUMPS AND THEN AFTER A FEW MORE PUMPS WILL GET THE NORMAL VACUUM ASSIST BACK. I HAVE GONE TO MY LOCAL HONDA DEALERSHIP AND ASKED THEM IF THERE ARE ANY TECHNICAL SERVICE BULLETINS ASSOCIATED WITH THE ISSUE AND THEY HAVE TOLD ME THAT THERE ARE NONE. I KNOW THAT BECAUSE OF THE HONDA INTEGRATED MOTOR ASSIST IN THEIR HYBRID VEHICLES, THERE IS AN EXTRA VACUUM SWITCH MODULE THAT CONTROLS THE BRAKE BOOSTER SO THAT IT CAN TURN THE ENGINE BACK ON DURING IDLE-STOP TO RESTORE BRAKE BOOSTING. I SUSPECT THAT THERE IS AN ISSUE ASSOCIATED WITH THAT 3-WAY JOINT THAT IS CAUSING INITIAL LOSS OF VACUUM. ONLINE FORUMS HAVE INDICATED POTENTIAL PREMATURE FAILURE IN THE BRAKE VACUUM HOSES. HTTP://REPAIRPAL.COM/FAILED-VACUUM-BRAKE-BOOSTER-HOSE-MAY-CAUSE-BRAKE-TO-FEEL-HARD-148

IT ALWAYS HAPPENS IN THE WINTER TIME, I GET IN MY CAR TO LEAVE AND I HAVE NO BRAKES. THE PEDAL IS VERY HARD/STIFF AND YOU HAVE TO PULL THE EMERGENCY BRAKE IN ORDER TO ACTUALLY STOP. IN FACT I ALMOST HIT A CAR TODAY AND THE CAR HAD ACTUALLY ALREADY BEEN WARM AND WENT INTO A PLACE FOR ABOUT 30 MIN AND I ASSUMED THEY WOULD STILL BE WARM, WRONG THAT'S WHEN I ABOUT HIT A VEHICLE BECAUSE I COULDN'T STOP! *TR