HP ZBook 15 G4 - Power Good (Troubleshooting) Lights

Table 6-5 System diagnostics failure codes and user actions (continued)
Test description Failure description
Error
code Suggested user actions
Chassis Fan Not
Detected (Front)
Fan Fan not operating correctly 90B The system fan may be malfunctioning. Replace the fan.
System Temperature Thermal shutdown has
occurred.
90D The System BIOS has detected your machine was previously shut
down to avoid overheating. Overheating may occur if the cooling
vents are blocked or the operating temperature exceeds the
system specications. The machine should return to normal
operation once the situation is resolved.
Fan Speed Failure The system has detected
that a cooling fan may not
be working properly.
90F Try the following:
●
Press Enter to clear the message and boot to the Windows
desktop.
●
Shut down Windows.
●
Clean the exterior of the vents to remove dust build-up
while the computer is O.
●
Check for a BIOS update.
Power Good (Troubleshooting) lights
HP has added troubleshooting power lights to mobile workstations to help troubleshoot power-on issues. The
lights indicate when the system board power rails are unstable and/or the system needs a hardware reset.
Power good lights
Power good lights, HP ZBook 15 G4 model location
These lights should be visible after removing the service door or bottom
cover. Consult with support for platform-specic locations of the lights.
Troubleshooting lights diagram
●
Example: System board is good. Lights that turn on briey (< 1 second) and immediately turn o indicate
normal function. In this case, system (3.3V), power good (3.3V), and system reset (3.3V) are all good and
88 Chapter 6 Troubleshooting guide