Changes

=== Mode 8 ===

=== Mode 8 ===

Periodically, the BCM sends polling requests amongst other data on the bus. These requests poll the ECM for sensor data and operational parameters used by the instrument cluster. A Mode 8 request is used to temporarily disable these messages from being sent. This essentially silences the BCM and quietens the bus, allowing for another device such as a computer or scan tool to transmit with a lower chance of a [https://en.wikipedia.org/wiki/Collision_domain#:~:text=A%20network%20collision%20occurs%20when%20more%20than%20one%20device%20attempts%20to%20send%20a%20packet%20on%20a%20network%20segment%20at%20the%20same%20time packet collision]. Unless another Mode 8 request is sent within a predetermined amount of time{{When}}, the BCM will automatically resume normal bus operation. The below table illustrates the full structure of a Mode 8 request.

Periodically, the BCM sends polling requests amongst other data on the bus. These requests poll the PCM for sensor data and operational parameters used by the instrument cluster. A Mode 8 request is used to temporarily disable these messages from being sent. This essentially silences the BCM and quietens the bus, allowing for another device such as a computer or scan tool to transmit with a lower chance of a [https://en.wikipedia.org/wiki/Collision_domain#:~:text=A%20network%20collision%20occurs%20when%20more%20than%20one%20device%20attempts%20to%20send%20a%20packet%20on%20a%20network%20segment%20at%20the%20same%20time packet collision]. Unless another Mode 8 request is sent within a predetermined amount of time{{When}}, the BCM will automatically resume normal bus operation. The BCM will respond with a frame containing a single data byte <code>08</code> with an ID of <code>F1</code> (a frame identical to the request). The below table illustrates the full structure of a Mode 8 request.

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=== Mode 9 ===

=== Mode 9 ===

Similar to [[#Mode 8|Mode 8]], a Mode 9 request will re-enable BCM chatter. A Mode 9 request can be sent to enable bus chatter earlier, rather than waiting for the original Mode 8 request to time out. This may be useful (and potentially good practice) if a device only requires bus silence for a short period of time, as bus silence for longer periods of time can lead to Check Engine warnings on the cluster{{Cn}}. The below table illustrates the full structure of a Mode 9 request.

Similar to [[#Mode 8|Mode 8]], a Mode 9 request will re-enable BCM chatter. A Mode 9 request can be sent to enable bus chatter earlier, rather than waiting for the original Mode 8 request to time out. This may be useful (and potentially good practice) if a device only requires bus silence for a short period of time, as bus silence for longer periods of time can lead to Check Engine warnings on the cluster{{Cn}}. The BCM will respond with a frame containing a single data byte <code>09</code> with an ID of <code>F1</code> (a frame identical to the request). The below table illustrates the full structure of a Mode 9 request.

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