Service-Information: Modular Control System (MCS)

 An increasing number of Modular Control System (MCS) units with digital data bus (D2B) and related components -- sound system amplifier, E-Call, CD Changer -- are found to be fault-free when returned for warranty assessment.

For complaints such as:

 Intermittent - Loss of sound (only with Code 810)

 CDC Icon flashes on screen

 CD not recognized,

special attention should be given to the condition of D2B wiring to eliminate it as a cause.

Potential Causes:

Loss of optical signal which result in intermittent D2B ring malfunctions due to:

 Routing conditions (sharp bends, misalignment)

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 Physical damage to the cable(s) (kinks, pinched)

Once compromised, signal attenuation may occasionally exceed allowable limits, thus causing intermittent failures. D2B fibers are very fragile and easily damaged when mishandled or stressed by poor routing conditions. The most damage-prone areas are:

 Directly behind the MCS unit

 At the E-Call unit

 At telephone installations (PSE)

Extra caution must always be exercised during removal and installation of these components.

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 Always ensure D2B cables are not:

 Trapped/Pinched

 Too sharply bent

 Wrapped around wire harnesses or other objects that could cause undue tension, stress, or damage.

Remedial Measures:

 Minimum radius allowed for cable bends is 25 mm.

 Connectors must be firmly attached, with fibers remaining relaxed and tension-free.

 Physical damage (kinks, sharp bends, pinched fibers) will cause permanent loss of safe operating margin.

 DAS contains complete step-by-step diagnostic procedures for D2B-related complaints and fault codes.

 WIS contains complete descriptions on D2B system, components, functions, and test equipment.

 As of 05/01: D2B cables are no longer integrated with the main wire harness. D2B cables are now contained in separate harness assemblies with modified routing for added protection and improved performance.

 Up to 05/01 (D2B fibers integrated with main harness): For major repair cases, installation of a new, self-contained D2B harness is recommended. It should be installed in its entirety, following new routing scheme. Cut off all unused fibers where they exit from original main wire harness to prevent later confusion.