ASE B5

Correct answer: B. The correct answer is B, the stabilizer bar. The stabilizer bar, also called a sway bar, resists body roll but does not locate the wheel or set camber, caster, or toe, so replacing it does not disturb alignment angles. Answer A is incorrect because replacing a MacPherson strut affects camber and often requires an alignment. Answer C is incorrect because a leaf spring locates the axle and affects ride height and angles, so replacing it typically requires an alignment check. Only the stabilizer bar can be replaced without altering wheel alignment. Answer D is incorrect because a control arm holds alignment-critical pivot points, so replacing it changes angles and requires an alignment.

Correct answer: C. A heated mirror is quickly checked by turning on the rear defrost, which powers the mirror's heating element, and then touching the mirror surface to feel for warmth. If the mirror warms, the grid is working, and if the heating grid element is damaged the entire mirror assembly must be replaced, because the grid is bonded into the glass and is not a separately serviceable part. Answer A is incorrect because a visual inspection for cracks does not confirm the heating grid actually operates. Answer B is incorrect because checking only the fuse skips the functional warmth test, and the grid cannot simply be repaired since it is not serviceable on its own. Answer D is incorrect because heated mirrors can in fact be functionally tested with the defrost-and-touch method.

Correct answer: A. A system with a wheel speed sensor at each of the four wheels and independent hydraulic control at each wheel is classified as a four channel system, because each wheel can be modulated on its own, reducing, holding, or increasing brake pressure at that wheel alone for the best possible control. Answer B is incorrect because a one channel system modulates the whole system through a single channel, far less independent control than four separate channels. Answer C is incorrect because a three channel system combines the two rear wheels onto a single shared channel rather than controlling all four independently. Answer D is incorrect because a two channel system controls wheels in pairs and does not provide four independent channels.

Correct answer: B. Pressurizing coolant raises its boiling point, which lets the cooling system run hotter without the coolant boiling over, while it does not change the coolant's freezing point, since freeze protection comes strictly from the antifreeze-to-water ratio and not from system pressure. Answer A is incorrect because pressure raises the boiling point instead of raising the freezing point and has no effect on freezing point. Answer C is incorrect because pressurization does not lower the freezing point and it raises rather than lowers the boiling point. Answer D is incorrect because pressure clearly does affect the boiling point by raising it, so saying it has no effect on either point is wrong.

Correct answer: D. An electric cooling fan wired to spin backwards moves air in the wrong direction and fails to pull sufficient air through the radiator, reducing heat rejection and causing the engine to overheat. Answer A is incorrect because a radiator cap rated at the correct pressure is operating as designed and does not cause overheating. Answer B is incorrect because a drive belt tensioned to specification is functioning normally and would not cause overheating. Answer C is incorrect because a thermostat that opens at the specified temperature is working correctly and would not cause the engine to overheat.

Correct answer: D. Answer D is correct because the proper procedure is to match-mark the U-joint cap to the differential yoke position, then disconnect the driveshaft from the yoke. Match-marking preserves the original rotational orientation so the driveshaft goes back exactly as it came off, maintaining balance and preventing vibration. Answer A is incorrect because a solid-axle driveshaft uses U-joints at the yoke, not a CV joint to the axle shaft, so the described marking point does not apply. Answer B is incorrect because it names the wrong connection point, the axle housing, and omits the critical match-mark that keeps the phasing correct. Answer C is incorrect because removing the U-joint caps risks losing the needle bearings, and it again skips match-marking the yoke position.

Correct answer: B. A valve clearance check is not easily performed to check a no-start condition, because it is an involved internal engine measurement rather than a quick diagnostic step. A battery voltage check, spark test, and fuel pressure test are all quick and direct checks that address the common causes of a no-start. Answer A is incorrect because a spark test is easily performed to check for spark during a no-start. Answer C is incorrect because a battery voltage check is easily performed and is a routine no-start diagnostic step. Answer D is incorrect because a fuel pressure test is easily performed to confirm fuel delivery during a no-start.

Correct answer: B. Door panel airbags may be inflated using sodium azide, a chemical compound used in some inflator designs to rapidly generate the gas needed for deployment. Answer A is incorrect because the inflator is not limited to compressed nitrogen only in this design. Answer C is incorrect because sodium hydroxide is a deployment byproduct rather than the inflation agent. Answer D is incorrect because hydraulic fluid is not used to inflate an airbag.

Correct answer: D. Torque steer is the condition that appears only while driving torque is applied, which is exactly what the description gives: a tug during hard acceleration that disappears at steady cruise and under braking. Answer A is incorrect because memory steer is a pull toward the direction of the last turn and is not tied to acceleration. Answer B is incorrect because drift is a mild constant pull that is present regardless of throttle position. Answer C is incorrect because wander is a straight-line tracking problem in which the vehicle requires constant correction at any steady speed, not only under power.

Correct answer: C. Nickel-metal hydride batteries used in hybrid electric vehicles should not be allowed to fully discharge, because a full discharge can damage the battery pack. Answer A is incorrect because these batteries should not be fully discharged before every recharge, since doing so risks damage. Answer B is incorrect because the batteries are affected by full discharge cycles, which can harm the pack. Answer D is incorrect because they should not be fully discharged before storage.

Correct answer: A. The lateral accelerometer supplies the cornering force signal input to the traction control ECM, allowing the system to measure the side-to-side force acting on the vehicle during cornering. Answer B is incorrect because the brake pressure sensor measures hydraulic pressure and does not supply cornering force data. Answer C is incorrect because the wheel speed sensor provides rotational speed data rather than cornering force. Answer D is incorrect because the steering angle sensor reports steering wheel position, not cornering force.

Correct answer: B. A duct that is disconnected or blocked reduces airflow to the cabin vents. A disconnected duct lets the blower output escape into the dash cavity or door area before it reaches the vent outlets, while a blocked duct that is collapsed, kinked, or plugged with debris prevents air from passing through. Both defects lower airflow at the affected vent through opposite mechanisms. Answer A is incorrect because a duct with a smooth, unobstructed interior allows air to flow freely to the vents. Answer C is incorrect because a duct properly sealed at every joint keeps the airflow contained and delivers it to the vents. Answer D is incorrect because a correctly routed duct directs air where it belongs and supports normal vent airflow.

Correct answer: C. The correct answer is C. The primary job of engine coolant is to maintain the engine at its proper operating temperature by absorbing heat from the block and carrying it to the radiator to be released. Answer A is incorrect because coolant heats the heater core to warm the cabin only as a secondary use; regulating engine temperature is its primary function. Heat management of the engine is the core role. Answer B is incorrect because coolant is not a general lubricant; while it may contain additives that protect the pump seal, its main purpose is heat transfer, not lubrication. Answer D is incorrect because coolant is not part of the air conditioning refrigerant loop; the Air Conditioning (A/C) system uses refrigerant, not engine coolant.

Correct answer: B. The battery should always be disconnected before working on the electrical system because working with it connected risks short circuits, sparks, and potential fire or personal injury from accidental current flow through the circuit being serviced. Answer A is incorrect because testing the circuit with the battery connected before disconnecting is unsafe and creates those hazards. Answer C is incorrect because taping a wire without disconnecting power does not remove the risk of short circuits or sparks during the repair. Answer D is incorrect because leaving the battery connected creates those exact hazards.

Correct answer: D. Using the collision advantage may help find the cause of a driveability problem, because the technician can apply knowledge of exactly what was damaged in the collision to focus the diagnosis on affected components rather than performing random checks. Answer A is incorrect because a tire alignment issue is diagnosed with alignment measurements, not by the collision advantage described here. Answer B is incorrect because a paint color mismatch is a refinishing concern, not a driveability issue addressed by the collision advantage. Answer C is incorrect because an upholstery tear is an interior trim problem unrelated to driveability diagnosis.

Correct answer: D. Answer D is correct because the clock spring holds a coiled ribbon wire with a limited amount of travel; if it is off center, turning the wheel runs it out of travel and breaks it. Answer A is incorrect because steering lock is a function of the ignition lock cylinder, not the clock spring. Answer B is incorrect because a continuously sounding horn indicates a shorted horn circuit, not an off-center coil. Answer C is incorrect because deployment threshold is set by the sensors and diagnostic module, not by clock spring centering.

Correct answer: B. A bolt-on structural component such as a front crossmember is typically not designed to be pulled or straightened with conventional frame straightening equipment. This type of part should never be sectioned and should rarely, if ever, be worked at all; because it is a bolt-on component rather than a welded structural member, the vehicle manufacturer's recommended repair is replacement with a new part. Answer A is incorrect because this type of part should never be sectioned. Answer C is incorrect because traditional frame straightening methods are not appropriate for a bolt-on component that does not lend itself to that repair. Answer D is incorrect because heating and reshaping by hand is a form of working the part, which should rarely if ever be done, and it is not the manufacturer-recommended repair for a bolt-on structural part.

Correct answer: B. The negative, or ground, battery cable is always disconnected first before electrical repair work. That cable ties the battery negative terminal to the vehicle chassis, which serves as the ground return path for the entire electrical system, so removing it first opens that path. With the ground open, a tool or wire that later touches the body while the technician works on the positive side cannot complete a circuit back to the battery, so no short or spark occurs. Answer A is incorrect because the alternator output wire is not part of the battery disconnect sequence and is not the first cable removed. Answer C is incorrect because the positive cable is disconnected last, not first, and removing it first would leave the ground path intact and defeat the safety purpose. Answer D is incorrect because the main fusible link is not the cable removed first, the procedure specifies disconnecting the negative cable.

Correct answer: D. A weakened hose only swells when it is loaded, so the fault is made visible by pressurizing the circuit and watching the hose while the pedal is held down. Answer A is incorrect because a hose at rest is unloaded and has returned to its normal size, so the measurement that matters is never taken. Answer B is incorrect because a grinding noise points to friction material worn down to its backing, not to a hose. Answer C is incorrect because pedal free play measures slack in the pushrod and linkage and says nothing about hose condition.

Correct answer: D. An R-12 air conditioning system uses Schrader valves at its service ports. R-134a systems, by contrast, use metric quick-connect service fittings, which is one of the ways the two systems are kept from being cross connected. Knowing which fitting belongs to which refrigerant helps a technician verify system type before service. Answer A is incorrect because an R-12 system does have dedicated service ports, they are the Schrader valve type. Answer B is incorrect because metric quick-connect fittings belong to R-134a systems, not R-12 systems. Answer C is incorrect because an R-12 system uses only Schrader valves, not both fitting types equally.