Advanced Vehicle Electrical and Electronic Systems
Advanced Vehicle Electrical and Electronic Systems
This domain tests multiplexed networks, electronic control modules, sensors, driver-assistance systems and high-voltage safety. Expect questions on CAN, LIN, module programming, calibration and electrical measurement.
Network and measurement essentials
A CAN bus is a twisted pair with two 120-ohm terminating resistors, giving about 60 ohms across the pair when isolated. With the bus live, expect differential signaling around 2.5 V, switching between roughly 3.5 V and 1.5 V. LIN is a single-wire local network. Communication faults often set U-codes. Use an oscilloscope for waveform shape and a multimeter for resistance and voltage drop, but never measure resistance on a live network. Module programming requires a stable voltage supply and correct software. ADAS calibration requires correct tyre pressures, ride height, fuel level, clean targets and a suitable space; some systems need a dynamic road calibration.
High-voltage safety
Treat orange cables as live. Isolate, lock out and tag, wait the specified time, then prove dead with a suitable tester before work.
Worked example
Multiple U-codes and a no-start. Reasoning: check battery and grounds first; measure CAN resistance at the diagnostic connector, expecting about 60 ohms. A reading of 120 ohms suggests one terminator or an open leg; 0 ohms suggests a short. Disconnect modules in turn to isolate the section. Do not replace the body control module first.
Traps
- Using an ohmmeter on a live CAN bus.
- Probing airbag or high-voltage circuits with a standard multimeter.
- Skipping ADAS calibration after suspension or windscreen work.
- Programming without a stable power supply.