Diagnostic - ISO11898

The Haldex Can bus uses 4 wires, 2 are for power supply, 2 for the communication (CAN High and CAN Low)

It can be used for ECU extensions, diagnostic or telematic.

Before to start the checking's, be sure you know the CAN bus layout of the vehicle. Depending on the ECUs mounted, you could find splitters and extension cables to link all the network together.

In practice, always start to check the CAN bus from one end to main ECU (EB+ or U-ABS), then check again the different cable or splitters separately.

Test points

Condition

Required value

Measured value

Comments

1 / 4

Power ON

B+

If the measured value is below B+, it can indicate a resistance in the wiring

Next steps :

check for oxidation marks in the connectors
check the continuity of the wires with ohmmeter (R<5Ω for correct operation)

2 / 4

Power ON

0V < V < 5V

The average voltage of CAN High wire is around 2.5V

Next steps :

check for oxidation marks in the connectors
check the continuity of the wires with ohmmeter (R<5Ω for correct operation)

3 / 4

Power ON

0V < V < 5V

The average voltage of CAN Low wire is around 2.5V

Next steps :

check for oxidation marks in the connectors
check the continuity of the wires with ohmmeter (R<5Ω for correct operation)

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