On a vehicle with CAN partial networking, supported controllers can remain asleep while other parts of the network are active. A suitable wake-up frame can target a controller or group. The presence of traffic therefore does not prove that every connected unit should be awake.
Sleep behaviour belongs to the system design
NXP’s partial-networking documentation describes selective wake-up using matching message information. This capability requires compatible hardware and configuration. It should not be assumed on every CAN-equipped vehicle.
When investigating a controller that seems unavailable, establish the expected operating state and wake-up conditions. A missing response while parked can mean something different from a missing response when the required function is active.
Battery-drain reports need a timeline
Record when the car was locked, which accessories were connected and when the symptom occurred. Diagnostic activity itself may affect sleep behaviour, so the test conditions should be documented. A capture made with a tool connected is not automatically representative of an untouched parked vehicle.
AXION can review a sleep or wake-up enquiry with the vehicle specification and previous measurements. The repair should address an established fault, not disable normal energy-management functions. Avoid adding wake-up devices or altering network configuration solely to keep a reluctant controller online.
Arrange an assessment
For complex electrical and network diagnostics, send the vehicle details and fault report to AXION. We support enquiries from drivers and garages. Workshop, postal and remote options depend on the job and are confirmed before booking.
Technical reference
Read the supporting technical documentation. The referenced design or vehicle application defines its scope; it is not a universal repair procedure.
Related reading
LIN classic and enhanced checksums in a diagnostic trace. Browse the automotive electronics repair library for other systems and symptoms.