Lenovo 90W AC/DC Combo Adapter User Manual page 22

Note: The adapter is designed to shut down and latch off when a fault is detected.
The fault must be removed AND the adapter must be disconnected for at least 10
seconds to reset the adapter.
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90W AC/DC Combo Adapter User's Guide
to your ThinkPad. If the original AC adapter operates correctly, contact
Service and Support for a replacement adapter.
b. If the adapter works for a period of time and then shuts off, check to insure
the adapter has proper ventilation. It is normal for the adapter to get warm
to the touch.
c. If the adapter is used in the Automobile Mode while the engine is off and
the adapter shuts off after a period of time, contact an automotive and
electrical technician to check your vehicle's electrical system for proper
output voltage with the adapter and your ThinkPad connected. Some
automobile manufacturer's designs do not provide sufficient voltage
(minimum 11.5 VDC) to operate the adapter under full load.