Power Good (Troubleshooting) Lights - HP ZBook 17 G4 Mobile Workstation Maintenance And Service Manual

Table 7-5 System diagnostics failure codes and user actions (continued)
Test description
Chassis Fan Not
Detected (Front)
Fan
System Temperature
Fan Speed Failure

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
These lights should be visible after removing the service door or bottom
cover. Consult with support for platform-specific locations of the lights.
Example: System board is good. Lights that turn on briefly (< 1 second) and immediately turn off indicate
●
normal function. In this case, system (3.3V), power good (3.3V), and system reset (3.3V) are all good and
troubleshooting lights should not be lit. However, other external lights should be lit as normal
afterward.
Error
Failure description code
Fan not operating correctly 90B
Thermal shutdown has 90D
occurred.
The system has detected 90F
that a cooling fan may not
be working properly.
Suggested user actions
The system fan may be malfunctioning. Replace the fan.
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 specifications. The machine should return to normal
operation once the situation is resolved.
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 Off.
● Check for a BIOS update.
Troubleshooting lights diagram
General troubleshooting steps 89