ASE A6 Electrical Electronics Practice Test
36. The #1 and #4 cylinders of a four-cylinder engine are misfiring. According to the schematic diagram above, which of the following is causing these misfires?
- A. There is an open at point A in the system.
- B. There is an open at point B in the system.
- C. There is an open at point C in the system.
- D. There is excessive resistance at point D of the system.
Answer A is wrong. Point A is a common ground for both drivers. Drivers are transistors. The computer uses them to control different actuators, like the coils shown above, usually by grounding the control circuit.
Answer B is correct. An open at point B results in no voltage input to the coil and a misfire code at both the number 1 and 4 cylinders.
Answer C is wrong. An open in the 2-3 coil’s power circuit will result in a no-spark problem with that coil only.
Answer D is wrong. Resistance in the crankshaft position sensor’s circuit will result in a corrupt signal and most likely a no-spark condition at both coils.
37. A windshield wiper motor operates intermittently and weak. Which of the following is MOST likely causing this condition?
- A. Loose mounting bolts.
- B. An open in the power circuit.
- C. Loose wiper arms.
- D. A seized windshield wiper motor.
Answer A is correct. Electrical components that use the chassis ground suffer high resistance in the ground circuit if the mounting bolts are loose. Many horns, windshield wiper motors, and aftermarket parts use the chassis/body ground.
Answer B is wrong. An open in the power circuit prevents motor operation at all times.
Answer C is wrong. Loose wiper arms are easily diagnosed during a visual inspection and result in scratches on the windshield's surface.
Answer D is wrong. A seized wiper motor prevents motor operation at all times.
38. View the electrical diagram above. The engine's cooling fan motor operates whenever the ignition is switched ON, even when the engine is cold. Which of the following would cause this continuous fan motor operation?
- A. Excessive resistance at point A of the system.
- B. An open at point B in the system.
- C. A short to ground at point C in the system.
- D. An open at point D of the system.
Answer A is wrong. Resistance in the (ECT) engine coolant temperature sensor's circuit alters and weakens the signal from the sensor.
Answer B is wrong. An open at point B results in no fan operation. The control module is unable to control (ground) the open circuit.
Answer C is correct. A short to ground at point C activates the relay causing the fan to run when the ignition is switched on, even when the engine is cold.
Answer D is wrong. An open at point D prevents fan motor operation.
39. The electrical symbol above represents a:
- A. Switch
- B. Connector
- C. Splice
- D. Circuit Breaker
Answer A is wrong. This is the standard symbol for a connector.
Answer B is correct. It's a universal symbol used in automotive schematics.
Answer C is wrong. Check for excessive resistance in a problem connector by performing a voltage drop test.
Answer D is wrong. Answer B is correct.
40. A technician uses an ohmmeter to test the four-pin brake light switch in the illustration for continuity. When the plunger is depressed, two connector pins have continuity, and two are open. Technician A says this is normal. Technician B says this is a brake switch with one (NO) normally open connection and one (NC) normally closed. Who is correct?
- A. Technician A
- B. Technician B
- C. Both A and B
- D. Neither A or B
Answer A is wrong. Modern switches also have circuits for the ECM, BCM, or EBCM controller.
Answer B is wrong. A faulty brake switch affects more than the stop lights. A failed switch also affects the shift interlock, torque converter clutch, ABS, traction control, and cruise control systems.
Answer C is correct. The manufacturer's manual will provide a diagram to identify these pins. Some switches have larger, normally open pins for the brake lights and smaller, normally closed pins for the ECM.
Answer D is wrong. Read the illustrated article by clicking the Read more... button.