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.
Communication and Hosted Diagnostics
The HPCM is the host controller for diagnostic trouble code (DTC) information for the following control modules:
- Accessory DC power converter module (APM)
- Battery energy control module (BECM)
- Motor control module (MCM) 1
- Motor control module (MCM) 2
- Auxiliary transmission fluid pump (ATFP) control module
The BECM will diagnose its own systems and determine when a fault condition is present. Diagnostics and system status is communicated from the BECM to the HPCM through the Hybrid LAN communication circuit.
In the event a hosted module communicates a fault condition, the HPCM will determine if hybrid operation is affected and notify the vehicle operator by requesting the MIL illuminate and/or by displaying a hybrid service required message. In addition, the HPCM will store the associated DTC information for retrieval by a scan tool. Some hosted modules may require an ignition cycle to clear certain DTCs from the HPCM.
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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.