Signal and Power Integrity
Why a signal can be “present” yet wrong, and how reference, ground and noise corrupt measurements.
Loading…
What you will learn
- Explain reference and ground integrity
- Recognise noise and voltage-drop effects on signals
- Test the reference and ground before the signal
Advertisement
A sensor signal is a voltage or current measured relative to a reference and a ground. If the reference is low or the ground has resistance, the ECU reads a plausible-looking but wrong value. Many “sensor faults” are actually integrity faults.
Advanced diagnosis means measuring the reference voltage and the ground voltage drop under load, and looking for noise from ignition, actuators or poor shielding. A correct number with a bad reference is still a wrong number.
Loading…
Key points
- Check reference and ground before the signal.
- Voltage drop on a shared ground corrupts many readings at once.
- Noise points to ignition, actuators or shielding.
Loading…
Key points
- A signal is only as good as its reference and ground
- Voltage drop corrupts sensor readings
- Noise and bad grounds cause implausible data
All values shown are training examples. Real thresholds depend on the manufacturer, engine, temperature and system — always confirm with the vehicle service documentation.
Advertisement