Communication occurs between two control modules via a "Two-wire bus system"

• Switch the ignition off.
• Disconnect both control modules
• Check whether there is a breakage in one of the bus lines.

Fig 1: Circuit Schematic - Checking For Breakage In One Of The Bus Lines, Two-Wire Bus System

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• Check whether there is a short between the bus lines.

Fig 2: Circuit Schematic - Checking For Short Between Bus Lines, Two-Wire Bus System

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• Check whether one of the bus lines is short-circuiting to positive or to Ground (GND)

Fig 3: ircuit Schematic - Checking For Short To Positive Or Ground, Two-Wire Bus System

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No malfunctions in the bus lines:

• Try changing the control module which can be changed with the shortest time input or cost
• If control module communication via the bus remains disrupted, change the second control module.