ASE Diesel Practice Test Questions and Answers well Explained Latest 2024/2025 Update 100% Correct.

The tandem rear axle air suspension ride height rises above normal as the vehicle is unloaded. Which of these could be the cause? (A) A kinked air spring (bag) supply line (B) A leaking height control valve (C) A plugged height control valve exhaust port (D) A leaking pressure protection valve - C The parking brakes fail to apply on a truck with air brakes. Technician A says that low air pressure in the spring brake chamber could be the cause. Technician B says that a ruptured spring brake diaphragm could be the cause. Who is right? (A) A only (B) B only (C) Both A and B (D) Neither A nor B - D A diesel engine has excessive black smoke when started in the morning. Which of these could be the cause? (A) A bad fuel injection nozzle (B) A restricted fuel filter (C) A blocked fuel tank vent (D) A leaking fuel return line - A Which of these can cause a no-start condition on a HEUI engine? (A) High fuel pressure (B) Low injection control pressure (C) High boost pressure (D) Low boost pressure - B A diesel engine is hard to start, but runs good after it has been primed and run for a few minutes. The most likely cause is a:(A) leaking injector line. (B) leaking fuel return line. (C) plugged fuel tank vent. (D) bad transfer pump check valve. - D A diesel engine with wet liners has been running too hot, and there is coolant in the crankcase. The most likely cause is: (A) a cracked block. (B) cracked liners. (C) leaking liner seals. (D) a leaking injector seal. - C Diesel engine cylinder liner protrusion (height) can be adjusted by selecting the correct size: (A) cylinder liner. (B) head gasket. (C) liner shim. (D) fire ring. - C An electronically-controlled diesel engine will not start. Any of these could be the cause EXCEPT a failed: (A) camshaft position sensor. (B) engine control module (ECM). (C) ECM ground circuit. (D) throttle position sensor (TPS). - D When a diesel engine is operated under a load, coolant continually comes out of the radiator overflow and there are bubbles in the radiator. Which of these is the most likely cause? (A) Too much coolant in the cooling system (B) A clogged radiator (C) A stuck-open thermostat (D) Compression leakage into the cooling system - DThe cause of a logged fault code in an electronic diesel engine has just been repaired. Technician A says that the codes should be cleared before releasing the vehicle. Technician B says that the customer's password should be reset before releasing the vehicle. Who is right? (A) A only (C) Both A and B (B) B only (D) Neither A nor B - A A diesel engine has low power and low turbocharger boost pressure is found. Technician A says that a leaking exhaust manifold could be the cause. Technician B says that a plugged turbocharger oil return line could be the cause. Who is right? (A) A only (B) B only (C) Both A and B (D) Neither A nor B - A A truck equipped with air brakes has an uneven braking problem. Which of these could be the cause? (A) A binding treadle (foot) valve (B) Low brake line air pressure (C) A bad brake drum (D) A bad governor - C A service brake on a truck with an air brake system releases too slowly. Technician A says that low air pressure could be the cause. Technician B says that a kinked air line could be the cause. Who is right? (A) A only (C) Both A and B (B) B only (D) Neither A nor B - B A service brake chamber leaks when the brakes are applied. Which of these could be the cause? (A) Excessive push rod travel (B) A bad chamber diaphragm(C) A broken chamber return spring (D) A misaligned push rod - B All the wheels on a truck with air brakes lock up when a small amount of pressure is applied to the treadle (foot) valve. Which of these could be the cause? (A) The application valve is bad. (B) The limiting valve is leaking. (C) The compressor regulator is set too high. (D) The brakes are adjusted too high. - A When an air reservoir tank is drained, there is an excessive amount of moisture. This could be caused by a: (A) cracked air compressor bracket. (B) clogged air compressor intake. (C) failed one way check valve. (D) failed air dryer purge valve. - D