ADT Vehicle Electrical Systems & Diagnostics 2

Question 1

When diagnosing an Audi's CAN bus network, you notice intermittent communication faults across multiple control modules. What is the FIRST test to perform?

Accepted Answer

Measure CAN bus termination resistance between the CAN-H and CAN-L wires

Answer

CAN bus termination resistance should measure approximately 60 ohms (two 120-ohm resistors in parallel); deviations indicate wiring or termination faults.

Question 2

An Audi A6 C8 battery management system shows a fault for 'battery sensor communication.' Which component contains the battery sensor on most modern Audi vehicles?

Accepted Answer

Negative terminal clamp (IBS sensor)

Answer

The Intelligent Battery Sensor (IBS) is integrated into the negative battery terminal clamp and communicates battery state-of-charge data via LIN bus.

Question 3

While testing an Audi alternator output with ODIS, the load response controller (LRC) function shows a delayed voltage reduction when electrical load increases. This indicates:

Accepted Answer

Normal alternator operation designed to reduce engine load spikes

Answer

The load response controller deliberately delays full charging voltage application to reduce sudden engine load from the alternator, which is normal Audi energy management behavior.

Question 4

An Audi Q7 4M has a fault code for 'terminal 30 undervoltage.' Terminal 30 in Audi's wiring convention refers to:

Accepted Answer

Permanent battery positive supply

Answer

Terminal 30 is the standard DIN 72552 designation for a permanent, unswitched battery positive supply always live regardless of ignition state.

Question 5

When using an oscilloscope to test an Audi wheel speed sensor (active Hall-effect type), what is the expected output signal?

Accepted Answer

Square wave that switches between approximately 0V and supply voltage

Answer

Active Hall-effect wheel speed sensors produce a digital square wave output, switching between low and high voltage as the magnetic encoder ring passes the sensor.

(ADT) Audi Diagnostic Technician Practice Test

(ADT) Audi Diagnostic Technician Practice Test

ADT Vehicle Electrical Systems & Diagnostics 2