ASE A5 Cheat Sheet 2026

The 25 highest-yield ASE A5 facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. A technician needs to loosen a corroded brake line fitting at a wheel cylinder. Which tool is the best choice to reduce the risk of rounding the fitting? → Flare-nut (line) wrench
2. When bench bleeding a master cylinder, why are the bleed tubes or fittings routed back into the reservoir with their ends below the fluid level? → To prevent air from being drawn back into the bore on the piston's return stroke
3. In a duo-servo drum brake with a primary and a secondary shoe, why is the secondary shoe lining typically longer or thicker than the primary shoe lining? → The secondary shoe does most of the braking, so it wears more
4. Before adjusting a rear parking brake cable on a vehicle with rear drum brakes, what should the technician verify first? → The rear service brakes are in good condition and properly adjusted
5. A technician uses a brake fluid tester and finds that the fluid's boiling point is well below the minimum for its DOT rating. What does this indicate? → The fluid contains too much moisture and should be replaced
6. A technician measures a brake drum and finds the friction surface is larger than the maximum diameter cast into the drum. What is the correct action? → Replace the drum
7. When checking the air gap of an adjustable wheel speed sensor, which tool should the technician use? → A nonmagnetic (brass or plastic) feeler gauge or paper shim
8. After replacing an ABS hydraulic control unit (modulator), what is the recommended way to remove air trapped inside the unit? → Use a scan tool automated bleed procedure to cycle the valves and pump
9. A brake pushrod gauge is used when installing a master cylinder on a power booster. What does the technician compare with this tool? → Booster pushrod protrusion against the depth of the master cylinder piston recess
10. A technician finds a brake hose that appears swollen along part of its length when the brake pedal is firmly applied. What action is correct? → Replace the hose
11. Why do many diesel-powered vehicles use an engine-driven or electric vacuum pump for the power brake booster? → Diesel engines produce too little intake manifold vacuum
12. On a vehicle with traction control that shares the ABS hydraulic unit, what can the system do when a drive wheel starts to spin on a slippery surface? → Apply the brake at the spinning wheel and/or reduce engine torque
13. Which of the following is a safe fluid to use for cleaning hydraulic brake components such as a master cylinder bore or caliper pistons during service? → Denatured alcohol or clean brake fluid
14. When a Hall-effect (active) wheel speed sensor is viewed on a lab scope while the wheel turns faster, what change should be seen in the waveform? → A square wave of constant amplitude whose frequency increases
15. Before measuring lateral runout of a front disc brake rotor with a dial indicator, what should the technician do first? → Make sure the wheel bearing has no excess play and the rotor is mounted correctly
16. Before disconnecting a brake line on an integral ABS with a high-pressure accumulator, what must be done first to relieve stored pressure? → Disconnect the wheel speed sensors and drive the vehicle
17. Which is the main purpose of the metering valve in a front disc/rear drum brake system? → To delay front brake application until the rear shoes have overcome their return springs
18. A booster check valve is removed from a vacuum booster and tested with a hand-held vacuum pump. Which result indicates a good valve? → It passes air only toward the engine side
19. A rotor measures 0.980 in. thick. The discard thickness marked on the rotor is 1.000 in. What should the technician do? → Replace the rotor
20. After the parking brake lever is released, the rear wheels still drag and the rear brakes overheat. Which is the most likely cause? → A seized or corroded parking brake cable
21. Why should brake fluid from a container that has been left open for a long time not be used when refilling the reservoir? → It absorbs moisture, which lowers its boiling point and promotes corrosion
22. Why must a brake fluid container be kept tightly capped when it is not in use? → Glycol-based brake fluid absorbs moisture from the air, which lowers its boiling point
23. A technician has just installed a new master cylinder. What should be done before it is connected to the brake lines? → Bench bleed the master cylinder to remove air from its bores and outlet ports
24. A vehicle pulls to the right whenever the brakes are applied. The brake pedal feels normal and there is no noise. Which condition is the most likely cause? → A seized caliper piston on the left front brake
25. Which is the main purpose of a proportioning valve in a brake system? → To reduce the rate of pressure increase to the rear brakes during heavy braking