Cummins X12 CM2350 X119B (2018 & Newer) Fault Code: 8156 PID: SPN: 521209 FMI: 9/9 Connectivity Module – Abnormal Update Rate

Lamp:
None

Reason:
Loss of communication with the connectivity module.

Effect:
None on performance.

Circuit Description:
The connectivity module is the data logging device. The connectivity module system collects data from the ECM via the vehicle J1939 network.
The connectivity module is also the predictive cruise control system. The predictive cruise control system sends commands to the ECM via the vehicle J1939 network. Predictive cruise control dynamically adjust the vehicle speed profile while the vehicle is operating in cruise control. The vehicle speed profile is optimized for fuel economy based on the upcoming road grade.

Component Location:
The connectivity module is either located on the engine or in the vehicle cabin.

Conditions for Running the Diagnostic:
This diagnostic runs continuously when the keyswitch is in the ON position or when the engine is running.

Conditions for Setting the Fault Codes:
The Engine Control Module (ECM) did not receive an expected message from the connectivity module.

Action Taken When the Fault Code is Active:
1. The ECM logs the fault code immediately when the diagnostic runs and fails.
2. The connectivity module may not operate.

Conditions for Clearing the Fault Code:
1. To validate the repair, perform a key cycle, start the engine and let it idle for 2 minute.
2. The fault code status displayed by the recommended diagnostic tool or equivalent will change to INACTIVE immediately after the diagnostic runs and passes.
3. The “reset all faults” command in the recommended diagnostic tool or equivalent can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

Shop Talk:
Possible causes of this fault code include:
1. The connectivity module is not receiving power. This can be caused by an open circuit in the power supply wire.
2. Rapid cycling of the keyswitch.
3. An open or short circuit on the J1939 data link circuit between the ECM and connectivity module.
4. Intermittent communications between the connectivity module and the primary engine ECM on the J1939 data link.
5. A damaged termination resistor in the J1939 data link.
6. A malfunctioning connectivity module.