ASE A6 Electrical Electronics Practice Test

A simple automotive CAN bus.

60. With the engine running the voltage between the DLC's pin 6 and ground measures 3.00 Vdc and the voltage between pin 14 and ground measures 2.00 Vdc. Technician A says this is normal. Technician B says these readings indicate crossed wires or shorted connector pins. Who is correct?

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

60.

A simple automotive CAN bus.

Answer A is correct. The reading changes with the activity on the bus. Typically the measurement is taken from the OBD II DLC of a system without a gateway or by back-probing the CAN HI and CAN LO pins of an easy-to-access control module's connector on a system with a gateway. The signal should be above 2.5 Vdc on the CAN HI wire and below 2.5 Vdc on the CAN LO wire.

Answer B is wrong. When CAN HI shorts to CAN LO, the voltage will remain around 2.5 Vdc on both wires.

Answer C is wrong. Technician A is correct.

Answer D is wrong. Technician A is correct.

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