Identify the pins responsible for screen backlight power (usually 19V) and backlight enable signals (3.3V).
What is the on your specific board?
Identify the current sensing resistor (often labeled R010 or PRxx ). This is the main highway for the 19V rail. hp probook 4540s boardview
: Click on the pin of that component to see every other spot on the motherboard that shares that electrical connection. This saves hours of manual probing with a multimeter. Conclusion Identify the pins responsible for screen backlight power