Five ASE A5 Brakes practice test questions, answers included.

1. Recall · Hydraulic, Power Assist, and Parking Brake Systems Diagnosis and Repair

   In a tandem master cylinder, the circuit fed by the primary (rear) piston has lost its fluid through a leak. What happens when the driver applies the brake pedal?

   1. The primary piston contacts the secondary piston and pushes it mechanically.
   2. The secondary piston cannot move without primary-circuit pressure, so neither circuit applies.
   3. The pedal stays high and firm because the secondary circuit takes the full load.
   4. The secondary circuit applies only after the pedal is pumped several times.
   Show the answer

   A. Correct. With no fluid to pressurize, the primary piston travels forward until it contacts the secondary piston and moves it directly, so the secondary circuit still develops pressure. The driver feels a much lower pedal and a longer stop, but half the system still brakes.

   Why not the others

   B. A tandem master cylinder is built so that a failed primary circuit does not disable the other one. The primary piston closes the gap and pushes the secondary piston mechanically, so the secondary circuit still applies.

   C. The pedal cannot stay high, because the primary piston must first travel through its empty chamber until it reaches the secondary piston. The secondary circuit does apply, but only after that extra pedal travel.

   D. Pumping is not needed: the secondary circuit applies on the first stroke once the primary piston has traveled far enough to push the secondary piston. A low pedal that must be pumped up points to air or excessive lining clearance instead.

2. Spec reading · Hydraulic, Power Assist, and Parking Brake Systems Diagnosis and Repair

   Both stop lamps are dim. With the pedal applied, a DMM connected between a stop lamp socket's ground terminal and the battery negative post reads 1.4 volts. The manufacturer allows no more than 0.1 volt on the ground side. What does this reading show?

   1. A ground-side voltage drop within its limit
   2. Excess resistance across the stop lamp switch contacts
   3. Excess resistance in the stop lamp fuse
   4. Excess resistance in the ground side of the circuit
   Show the answer

   D. Correct. The meter reads the voltage lost between the lamp's ground terminal and the battery while current flows, and 1.4 volts is fourteen times the 0.1-volt limit. That lost voltage is taken from the bulbs, so they glow dim; the ground connection or wire is cleaned or repaired and the drop rechecked.

   Why not the others

   A. The limit is 0.1 volt, and 1.4 volts is far over it. A reading this high shows excess resistance in the ground side.

   B. The stop lamp switch is on the feed side of the bulbs, and this meter is connected only across the ground side, from the socket ground to the battery negative post. The 1.4-volt reading is lost in the ground path.

   C. The fuse is on the feed side, ahead of the switch, and is not part of the path this meter is measuring. The reading shows a drop on the ground side of the circuit.

3. Recall · Drum Brake Diagnosis and Repair

   In a duo-servo drum brake, what carries the primary shoe's force to the secondary shoe during a forward stop?

   1. The adjuster screw at the lower shoe ends
   2. The parking brake strut between the shoe webs
   3. The anchor pin above the wheel cylinder
   4. The wheel cylinder pistons and shoe links
   Show the answer

   A. Correct. The turning drum drags the primary shoe with it, and the primary shoe pushes through the adjuster screw at the bottom into the secondary shoe. That force adds to the secondary shoe's own hydraulic push and drives its upper end against the anchor pin, which is why the secondary shoe does most of the braking in a forward stop.

   Why not the others

   B. The parking brake strut spreads the shoes when the parking brake lever is pulled; it is spring-loaded and is not the link that passes servo force between the shoes. That link is the adjuster screw at the bottom of the shoes.

   C. The anchor pin stops the secondary shoe in a forward stop and passes the braking torque into the backing plate; it does not connect one shoe to the other. The primary shoe's force reaches the secondary shoe through the adjuster screw at the bottom.

   D. The wheel cylinder pistons push both shoe tops outward with hydraulic force, but they do not pass force from one shoe to the other. The servo force travels from the primary shoe through the adjuster screw into the secondary shoe.

4. Recall · Disc Brake Diagnosis and Repair

   What does the square-cut piston seal in a disc brake caliper do when the driver releases the brake pedal?

   1. It flexes back and draws the piston slightly away from the pad.
   2. It holds residual pressure to keep the pads against the rotor.
   3. It acts as a spring that returns the piston to the bottom of its bore.
   4. It opens a passage that returns fluid to the master cylinder.
   Show the answer

   A. Correct. As pressure builds, the seal deflects with the piston; on release it springs back to its square shape and pulls the piston back a small amount, giving the pads running clearance. As the pads wear, the piston slides through the seal, so the caliper adjusts itself.

   Why not the others

   B. Disc brake calipers do not hold residual pressure; pressure left in the bore would keep the pads dragging. The square-cut seal relaxes on release and draws the piston back slightly for running clearance.

   C. The seal pulls the piston back only slightly and leaves it close to the pad; a piston returned to the bottom of its bore would make the first pedal stroke very long.

   D. Fluid returns to the reservoir through the master cylinder's own ports when its pistons return, not through a passage at the caliper. The caliper seal seals the piston and flexes back to retract it slightly.

5. Recall · Electronic Brake Control Systems: Antilock Brake System (ABS), Traction Control System (TCS), and Electronic Stability Control System (ESC) Diagnosis and Repair

   As wheel speed increases, the signal from a passive (magnetic, variable-reluctance) wheel speed sensor:

   1. rises in both frequency and AC voltage.
   2. rises in frequency while its voltage stays the same.
   3. changes to a DC voltage that climbs with speed.
   4. rises in AC voltage while its frequency stays the same.
   Show the answer

   A. Correct. A passive sensor is a coil around a magnet, and each passing tone-ring tooth induces one AC cycle. Faster teeth mean more cycles per second and a faster change in magnetic flux, so frequency and voltage both climb; this is why a weak sensor or wide air gap shows up first at low speed.

   Why not the others

   B. A signal whose frequency rises at a constant voltage is the digital square wave of an active sensor. A passive coil's output voltage grows with speed because the flux changes faster as the teeth pass more quickly.

   C. A passive sensor never produces a DC level: each tooth passing the magnet induces one AC cycle. The module reads speed from how many cycles arrive per second, so frequency rises along with the AC voltage.

   D. The voltage does rise, but the frequency cannot stay the same: each tooth makes one cycle, so more teeth per second means a higher frequency. Frequency is the value the module actually uses to calculate wheel speed.

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