T4 BRAKES ASE QUESTIONS AND
ANSWERS
Which09of09the09following09could09cause09the09brakes09on09a09truck09to09wear09too09f
ast?
A.09glazed09drums
B.09wrong09linings09installed
C.09Low09air09pressure09
D.09governor09cut09out09pressure09-09ans--✔✔B.09wrong09linings09installed
which09of09the09following09could09cause09one09brake09on09a09truck09to09wear09faster09
than09the09others?
A.09mismatched09service09brake09chambers
B.09mismatched09parking09chambers
C.09low09air09pressure09in09service09tanks
D.09governor09cut09out09too09low09-09ans--✔✔A.09mismatched09service09chambers
what09force09is09used09to09apply09the09foundation09brake09wheel09cylinders?09
A.09hydraulic09from09the09steering09reservoir09
B.09mechanical09
C.09electrical09
D.09hydraulic09from09the09master09cylinder09-09ans--✔✔D.
there's09an09audible09air09leak09from09under09the09dash09when09the09foot09valve09is09
applied.09technician09A09says09the09double09check09valve09may09be09faulty.09Tech09B
09says09the09single09check09valve09may09be09faulty.09who's09correct?09-09ans--
✔✔Tech09A09only
on09a09straight09truck09equipped09with09air09brake,09the09secondary09tank09pressure09
gauge09falls09to09zero09when09the09wet09tank09air09is09drained.09Tech09A09says09the09
one09way09check09valve09is09faulty,09Tech09B09says09the09foot09valve09may09be09fault
y.09Who's09correct?09-09ans--
✔✔Tech09A09only.09one09way09check09valve09protects09secondary09tank
A09loose09wheel09bearing09adjustment09can09cause09a09faulty09wheel09speed09sensor
09and09a09wheel09speed09sensor09code09-09ans--✔✔
, Air09dryer09purges09too09often.09Tech09A09says09the09air09dryer09delivery09check09Val
ve09may09be09faulty.09Tech09B09says09a09leaking09wet09tank09could09be09the09cause.0
9Who's09correct?09-09ans--✔✔C.09Both09Techs.
The09safety09valve09releases09on09the09air09tank.09Which09is09the09most09likely09caus
e?09
A.09plugged09line09from09the09supply09tank09to09governor.09
B.09faulty09tractor09protection09valve09
C.09stuck09spitter09on09the09air09drier
D.09faulty09secondary09tank09-09ans--
✔✔A.09if09the09line09was09plugged,09the09governor09would09not09unload09the09compre
ssor
A09truck09with09hydraulic09disc/
drum09brakes09has09a09high09firm09pedal09with09poor09stopping.09what09could09be09th
e09cause?09-09ans--✔✔The09brake09linings09are09glazed!
09Glazed09brake09linings09will09allow09the09pedal09to09feel09high09and09firm09with09no0
9stopping09power
Air09builds09on09a09truck09in091.509minutes.09The09specs.09manual09says09it09should09t
ake093.509min.09Tech09A09says09the09air09tanks09could09have09water09build09up.09Tec
h09B09says09the09air09tanks09could09have09oil09built09up.09Whos09correct?09-09ans--
✔✔C.09Both09technicians.09Any09Build09up09reduces09volume09for09stored09air
Brake09fluid09is09leaking09from09the09rear09of09a09master09cylinder09on09a09hydro09boo
st09brake09system.09What09is09the09likely09cause?09-09ans--✔✔Primary09seal09leaking.
Air09pressure09build09up09time09on09a09gear09driven09compressor09is09greater09than09
specifications.09What09is09the09cause?09
A.09a09slipping09drive
B.09a09leaking09service09relay
C.09leaking09primary09tank
D.09leaking09parking09brake09chamber09-09ans--
✔✔C.09A09leaking09primary09air09tank09causes09extended09air09build09up09time
air09leaks09from09the09left09front09modulator09valve09during09service09operation.09Ther
e09are09no09ABS09codes.09What09is09the09cause?09-09ans--✔✔Modulator09Valve09seat
air09is09leaking09from09a09quick09release09valve09mounted09on09the09front09axle09durin
g09service09application.09What09is09the09cause?09-09ans--✔✔Quick09release
The09three09ports09on09a09governor09are:09-09ans--
✔✔Reservoir,09Unloaded09and09exhaust
Pressure09valves09open09at09:09-09ans--✔✔150PSI
ANSWERS
Which09of09the09following09could09cause09the09brakes09on09a09truck09to09wear09too09f
ast?
A.09glazed09drums
B.09wrong09linings09installed
C.09Low09air09pressure09
D.09governor09cut09out09pressure09-09ans--✔✔B.09wrong09linings09installed
which09of09the09following09could09cause09one09brake09on09a09truck09to09wear09faster09
than09the09others?
A.09mismatched09service09brake09chambers
B.09mismatched09parking09chambers
C.09low09air09pressure09in09service09tanks
D.09governor09cut09out09too09low09-09ans--✔✔A.09mismatched09service09chambers
what09force09is09used09to09apply09the09foundation09brake09wheel09cylinders?09
A.09hydraulic09from09the09steering09reservoir09
B.09mechanical09
C.09electrical09
D.09hydraulic09from09the09master09cylinder09-09ans--✔✔D.
there's09an09audible09air09leak09from09under09the09dash09when09the09foot09valve09is09
applied.09technician09A09says09the09double09check09valve09may09be09faulty.09Tech09B
09says09the09single09check09valve09may09be09faulty.09who's09correct?09-09ans--
✔✔Tech09A09only
on09a09straight09truck09equipped09with09air09brake,09the09secondary09tank09pressure09
gauge09falls09to09zero09when09the09wet09tank09air09is09drained.09Tech09A09says09the09
one09way09check09valve09is09faulty,09Tech09B09says09the09foot09valve09may09be09fault
y.09Who's09correct?09-09ans--
✔✔Tech09A09only.09one09way09check09valve09protects09secondary09tank
A09loose09wheel09bearing09adjustment09can09cause09a09faulty09wheel09speed09sensor
09and09a09wheel09speed09sensor09code09-09ans--✔✔
, Air09dryer09purges09too09often.09Tech09A09says09the09air09dryer09delivery09check09Val
ve09may09be09faulty.09Tech09B09says09a09leaking09wet09tank09could09be09the09cause.0
9Who's09correct?09-09ans--✔✔C.09Both09Techs.
The09safety09valve09releases09on09the09air09tank.09Which09is09the09most09likely09caus
e?09
A.09plugged09line09from09the09supply09tank09to09governor.09
B.09faulty09tractor09protection09valve09
C.09stuck09spitter09on09the09air09drier
D.09faulty09secondary09tank09-09ans--
✔✔A.09if09the09line09was09plugged,09the09governor09would09not09unload09the09compre
ssor
A09truck09with09hydraulic09disc/
drum09brakes09has09a09high09firm09pedal09with09poor09stopping.09what09could09be09th
e09cause?09-09ans--✔✔The09brake09linings09are09glazed!
09Glazed09brake09linings09will09allow09the09pedal09to09feel09high09and09firm09with09no0
9stopping09power
Air09builds09on09a09truck09in091.509minutes.09The09specs.09manual09says09it09should09t
ake093.509min.09Tech09A09says09the09air09tanks09could09have09water09build09up.09Tec
h09B09says09the09air09tanks09could09have09oil09built09up.09Whos09correct?09-09ans--
✔✔C.09Both09technicians.09Any09Build09up09reduces09volume09for09stored09air
Brake09fluid09is09leaking09from09the09rear09of09a09master09cylinder09on09a09hydro09boo
st09brake09system.09What09is09the09likely09cause?09-09ans--✔✔Primary09seal09leaking.
Air09pressure09build09up09time09on09a09gear09driven09compressor09is09greater09than09
specifications.09What09is09the09cause?09
A.09a09slipping09drive
B.09a09leaking09service09relay
C.09leaking09primary09tank
D.09leaking09parking09brake09chamber09-09ans--
✔✔C.09A09leaking09primary09air09tank09causes09extended09air09build09up09time
air09leaks09from09the09left09front09modulator09valve09during09service09operation.09Ther
e09are09no09ABS09codes.09What09is09the09cause?09-09ans--✔✔Modulator09Valve09seat
air09is09leaking09from09a09quick09release09valve09mounted09on09the09front09axle09durin
g09service09application.09What09is09the09cause?09-09ans--✔✔Quick09release
The09three09ports09on09a09governor09are:09-09ans--
✔✔Reservoir,09Unloaded09and09exhaust
Pressure09valves09open09at09:09-09ans--✔✔150PSI
