Safety Systems

Hybrid Safety Systems
The Sierra/Silverado hybrid truck has safety systems designed to shut down and prevent vehicle operation should and unsafe situation occur. First responders should be aware of the following safety systems on the hybrid truck option:

- Automatic operation of the battery cut off switch for 42-volt system

- APO System
High voltage interlock look
Hood ajar switch
Door ajar switch
Ground fault detection circuit

- OnStar




Battery cut-off (BCO) Switch
Automatically triggered when:

- An airbag is deployed from a frontal impact.

- An impact to the passenger door is detected.

Note
A passenger side impact will not deploy the front airbags.

Side impact sensor
- Activates the battery cut-off switch to disable energy flow and terminate the operation of the SGCM, which will terminate the APO circuit.

- Enables the detection of an impact to the passenger door.

- Located in the passenger door due to the location of:
- The SGCM power cables
- A 120-volt wiring harness located in the body sill plate.
- The Service Disconnect Switch.




High Voltage Interlock Loop
- Provides a means for the SGCM to determine and monitor the integrity of the 120-volt wiring harness.

- The interlock signal creates a continuous electrical loop starting from the SGCM, going through both power outlets, and ending back at the SGCM.

- Should a 120-volt harness connector be disconnected, the SGCM:
- Issues an auxiliary power outlet fault.
- Terminates electrical operation of the 120-volt circuit.




Hood ajar switch
The hood ajar switch communicates whether the hood is open of closed. The engine cannot auto-start if the hood is either ajar or open. This ensures that the engine does not start unexpectedly when someone is servicing the vehicle. Note that the hood can be opened after the engine is running and the engine will remain running, as with other vehicles.

Note:
If the engine is off, it can still be started by turning the ignition key to the crank position, just as you would normally do.




Door ajar switch
If the vehicle is in the automatic engine start-stop mode and in Park with the engine off, the engine will start if either vehicle door is opened.







Ground Fault Detection Circuit
- Contained within the SGCM.

- monitors current flowing between the neutral and hot wire.

- When a circuit imbalance of more than several milliamps is detected:
- Operation of the 120-volt auxiliary power outlet circuit is terminated.
- The APO indicator flashes.




OnStar
Either airbag deployment or a side impact will cause OnStar to send a signal to the OnStar Center.