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VACUUM FITTINGS. ALSO TUNE OR REPAIR
REPLACE OR REPAIR VACUUM HOSE AND
IF VACUUM SUPPLY IS BELOW 12 INCHES-
SPEED CONTROL VACUUM PORT ON POWER UNIT. WITH ENGINE
IF PEDAL DOES NOT DROP, CONNECT VACUUM GAUGE TO
ENGINE OFF. DEPRESS AND RELEASE BRAKE PEDAL SEVERAL
DEPRESS PEDAL AND HOLD WITH LIGHT EFFORT OF 15 TO 25
IF POWER UNIT IS OPERATING, PEDAL WILL FALL SLIGHTLY AND
THEN HOLD. LESS EFFORT WILL BE NEEDED TO APPLY PEDAL.
WHEN ADEQUATE VACUUM SUPPLY IS OBTAINED, REPEAT BASIC
LOW VACUUM CAUSES EARLY BOOSTER RUNOUT WHICH CAN BE
AT WARM IDLE CHECK FOR PROPER VACUUM.
ENGINE AS REQUIRED.
TIMES TO REMOVE VACUUM FROM POWER UNIT.
MISTAKEN FOR PEDAL GOES TO FLOOR CONDITION.
NO
JX
DIAGNOSIS AND TESTING (Continued)
NO
BASIC TEST
LBS., AND START ENGINE.
YES
YES
UNIT IS DEFECTIVE AND
INCHES OR MORE-POWER
IF VACUUM SUPPLY IS 12
SHOULD BE REPLACED.
CHART 3 POWER BRAKES
POWER BRAKE SYSTEM DIAGNOSTICS
TEST.
REMOVE THE A/C VACUUM CONTROL LINE (IF SO EQUIPPED) FROM THE BOOSTER
START THE ENGINE. ALLOW A WARM-UP PERIOD SO THAT THE ENGINE REACHES
ATTACH A VACUUM GAUGE TO THE SPEED CONTROL NIPPLE ON THE BOOSTER
MINUTE, REPEAT PROCEDURE TO CONFIRM READINGS. LEAKAGE SHOULD BE LESS
PLY HOSE TO THE BOOSTER. IF VACUUM DROP EXCEEDS 1.0 INCH Hg IN ONE
WITH VACUUM LINE PLIERS (TOOL NUMBER C4390), CLOSE OFF THE VACUUM SUP-
APPLY LIGHT EFFORT (APPROXIMATELY 15 POUNDS OF PEDAL FORCE) TO THE
BRAKE PEDAL AND HOLD STEADY IN THIS POSITION. DO NOT MOVE THE PEDAL
LEAK
BOOSTER IS NOT DEFEC-
TEST-BRAKES
15 SECONDS, REPEAT PROCEDURE TO CONFIRM READINGS. LEAK-
THE VACUUM GAUGE. IF VACUUM DROP EXCEEDS 3.0 INCHES Hg IN
BOOSTER. ALLOW FIVE SECONDS FOR STABILIZATION AND OBSERVE
TANT CLOSE OFF THE VACUUM SUPPLY HOSE TO THE BRAKE
USING VACUUM LINE PLIERS (TOOL NUMBER C4390), HAVE AN ASSIS-
FROM THIS POSITION AS IT WILL AFFECT THE LEAKAGE READING.
APPLIED
LEAK
REMOVE THE VACUUM HOSE OR RUBBER CAP FROM THE SPEED CONTROL OUTLET NIPPLE ON THE
AGE SHOULD BE LESS THAN 3.0 INCHES Hg IN 15 SECONDS.
YES
VACUUM LEAK TEST
YES
CHECK VALVE. PLUG ANY REMAINING OPEN NIPPLES.
TIVE.
TEST-BRAKES
BOOSTER IS DEFECTIVE AND SHOULD BE
BOOSTER IS DEFECTIVE AND SHOULD
APPLIED
NO
CHECK VALVE. CAP OFF THE NIPPLE.
THAN 1.0 INCH Hg IN ONE MINUTE.
NOT
NO
BRAKES
NORMAL IDLE SPEED.
BE REPLACED.
REPLACED.
BOOSTER CHECK VALVE.
5 - 11
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