The diagnostic tool shows "Ring open-circuit on O-bus detected".

Read the instructions below then start the fault diagnostic procedure.

Symptom: The diagnostic tool shows "Ring open-circuit on O-bus detected".

Ring open-circuit on O-bus detected

Fault symptom

The diagnostic tool shows "Ring open-circuit on O-bus detected".

Diagnostic help

To localise the ring open-circuit, run diagnostics "Ring open-circuit position, O-bus" under the All/Bus menu and follow the instructions in the diagnostic tool.

Communication with CIM is necessary for Tech 2 to be able to communicate with all systems.

The Diagnostic instrument main menu "All systems/Read configuration" shows a list of those systems with which the vehicle in question was equipped before the fault was detected.

The current status of each system is shown to the right.

"OK" if control module communicates correctly.

"MISSING" if control module is not on the bus.

"ADDED" if the control module has not yet been added.

"NOT EQUIPPED" indicates that the control module is not fitted to the vehicle.

NOTE: applies before reset of bus configuration.

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Functions in the diagnostic tool related to the fault

•	Read / Reset Bus Configuration

•	Read / Clear Bus Off Counter

•	Response Test

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WARNING!

The visible red light is of laser class 1. Do not look directly into the optical fibre or the control module connector at a close distance. If there is less than 20 mm distance between the eye and the light source, the eye may be injured.

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Checking the wiring harness

IMPORTANT

Move the wiring harness at several spots and in several directions to reveal intermittent breaks and short-circuits. Check switches, connectors and crimp connections for oxidation, retracted pins and pin clamping force.