Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Power Up Sequence
The TCM conducts a power up sequence every time the ignition is turned from the OFF to the START position, if the gear selector is in PARK or NEUTRAL. During the power up sequence the TCM:
- initializes and begins controller area network (CAN) communications with the PCM and the BECM.
- requests the BECM to close the high voltage contactors.
- illuminates the green ready indicator indicating the vehicle is ready to drive in electric, gasoline, or a combination of electric and gasoline modes.
- if required, requests the PCM to start the internal combustion engine. The internal combustion engine will not start if the gear selector is in NEUTRAL. The internal combustion engine starts if it is required for cabin heating, windshield defrost or the outside temperatures are low. The internal combustion engine also starts if the high voltage battery charge is low.
If a concern is detected during the power up sequence, the TCM may initiate LOS mode and store a DTC.
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.