ASE A6 Electrical Electronics Practice Test

Voltage drop test

6. An engine's starter is cranking slowly. The battery has passed all testing, and the ignition has been disabled for a starter voltage drop test. While cranking the engine, the voltage readings at the battery and starter both indicate 10.03 volts. Technician A says these test results indicate a bad starter. Technician B says there is too much resistance in the positive battery cable. Who is correct?

  • A. Technician A
  • B. Technician B
  • C. Both A and B
  • D. Neither A or B

6.

Answer A is correct. Though the starter (the load) consumes all the voltage, internal problems like resistance, worn brushes, and bad bushings are causing it to turn slowly.

Answer B is wrong. If the battery and starter voltage readings differ, check the terminals, cables, and connections for resistance.

Answer C is wrong. Technician A is correct.

Answer D is wrong. Technician A is correct.

Click to Enlarge.

7. The engine's electric radiator cooling fan motor illustrated above does not operate unless commanded ON with a bidirectional scan tool. Technician A says the vehicle most likely has a faulty fan relay. Technician B says a faulty engine coolant temperature sensor or circuit would result in this condition. Who is correct?

  • A. Technician A
  • B. Technician B
  • C. Both A and B
  • D. Neither A or B

7.

Answer A is wrong. The relay and the circuit work when commanded ON by the scan tool.

Answer B is correct. Use the scan tool's bi-directional control to eliminate the controller's output, the fan motor, and the circuit as the cause. A problem with the engine coolant temperature circuit would result in this condition.

Answer C is wrong. Technician B is correct.

Answer D is wrong. Technician B is correct.

Click to Enlarge.

8. The right-side backup light in the diagram above is dim. The other light is normal. Which of the following is causing this condition?

  • A. Resistance at point A.
  • B. An open at point B.
  • C. An open at point C.
  • D. Resistance at point D.
Backup light circuit.

8.

Answer A is wrong. Resistance in the connection at point A results in dim (both) backup lights.

Answer B is wrong. An open circuit in the neutral safety switch results in inoperative backup lights.

Answer C is wrong. An open at point C results in an inoperative left-side backup light.

Answer D is correct. Excessive resistance in the connection at point D results in a dim right-side backup light.

Click to Enlarge.

9. The resistance between pins 6 and 14 of the OBD II connector above measures 60 ohms. Technician A says this is correct. Technician B says the modules must be powered down or the battery disconnected to test resistance in the CAN bus. Who is correct?

  • A. Technician A
  • B. Technician B
  • C. Both A and B
  • D. Neither A or B

9.

Answer A is wrong. CAN buses use twisted pair wires that reduce noise and interference. Twisted pair wire has an impedance of around 120 ohms.

Answer B is wrong. All modules must be powered down, or the vehicle's battery disconnected to measure resistance in the CAN bus circuit. Testing a powered circuit can damage the ohmmeter.

Answer C is correct. To prevent reflection, the CAN bus has two 120 Ohm resistors placed in parallel. They are often inside a control module like the ECM. This configuration results in 60 Ohms of resistance on the bus.

Answer D is wrong. Learn more about the CAN bus by clicking the Read more button.

10. A vehicle's air conditioner blower motor only works at high speed. Technician A says to check the blower motor resistor. Technician B says this is most likely caused by a loose ground connection. Who is correct?

  • A. Technician A
  • B. Technician B
  • C. Both A and B
  • D. Neither A or B

10.

Answer A is correct. A blower motor resistor uses resistance to control blower motor speeds.

Answer B is wrong. Typically, a loose connection causes an inoperative or intermittent condition.

Answer C is wrong. Technician A is correct.

Answer D is wrong. Technician A is correct.