Example 3:

The codes stored in the DTC memory enable you to establish that transmission and reception are not possible on any of the control modules.

Fig 1: Malfunction Messages In CAN Bus System - Example 3

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Fig 2: CAN Bus System Schematic - Example 3

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• Switch the ignition off.
• Disconnect the control modules linked by the bus lines and examine these for short-circuiting with one another.

• Check the bus lines for a short-circuit to positive and to Ground (GND).

Fig 3: Circuit Schematic - Checking The Bus Lines For A Short-Circuit To Positive And To Ground

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• If you are unable to find any cause for the "Hardware malfunction" malfunction in the bus lines, check whether one of the control modules is responsible for this malfunction.

  All the control modules which communicate via the CAN bus system must still be disconnected at this point. The ignition must be off.

• Connect one of the control modules.
• Connect one of the scan tools. Switch the ignition on and clear the DTC memory of the control module you have just connected. End Output from the scan tool using Function 06, "End Output"
• Switch the ignition off and then on again.
• Leave the ignition switched on for 10 seconds. Then check the DTC memory of the control module that has just been connected, using the scan tool.
• If "Hardware malfunction" is read out, replace the control module you have just connected.
• If "Hardware malfunction" is not read out, connect the next control module and repeat this procedure.