Examples of signals into data bus (used by engine control module)

• Cruise control system
• Ignition timing influences

In addition to the engine control module, other control modules exchange information via the data bus as well, as this example shows.

If the automatic transmission control module detects that signals are missing or faulty, the data bus itself, another system or a component of another system may be faulty.

Therefore, always perform OBD of affected control modules.