Checking for a Short-Circuit in the CAN Bus System, Low Speed Network

Checking for a short-circuit in the CAN bus system, low speed network

Checking for a short-circuit
Disconnect the upper electronic module from the bus cable (disconnect the connector from the control module).
Measure the resistance at the connector between terminals #3 and #5. The resistance must be 120 ohms.

Note! Take care that you measure directly at the connector so that it is not damaged.

If the resistance is 0 ohms between the terminals, there short-circuit somewhere in the bus system.

Other information:
- To connect the breakout box to the upper electronic module, see Connecting the breakout box Connecting the Breakout Box
- For further information about the connectors and bus cable, see the wiring diagram.







ohms

Is the resistance 0?

Yes - permanent

No - Fault-tracing information

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Checking the connectors and bus cable, permanent
Locate the bus cable. Use the wiring diagram. Check the wiring in different stages to localize where in the bus the fault is (the fault may be anywhere in the bus cable).

Hint: It is possible to get an approximate location of the fault by checking which functions are not working in the car and then relating the functions to the relevant control module.

Hint: Remember that the CAN bus is a communication network. There are no fuses, switches or sensors.

Short-circuit between the bus cables: Use an ohmmeter between the cables to find short-circuits between them. If the reading is 0 ohms between the CAN bus cables there is a short-circuit between them. In particular check the pins and terminals in this way. See Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.

Other information:
- To connect the breakout box to the upper electronic module, see Connecting the breakout box Connecting the Breakout Box
- For further information about the connectors and bus cable, see the wiring diagram.








Continue - FAULT FOUND

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Fault-tracing information
No fault detected in this fault-tracing.

Continue - FAULT FOUND

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