Modular Control System (MCS) Malfunctions (82.60/194)

Publication date: 2002-05-06
Reference number: 82.60/194

MODULAR CONTROL SYSTEM (MCS) MALFUNCTIONS

TECHNICAL SERVICE BULLETIN

Reference Number(s): T-B-82.60/194, Date of Issue: May 6, 2002

MERCEDES-BENZ:	Model 163.154/172/174/175, Model Year 2002
GROUP:	82 - Body Electrical System, Telephone (CTEL), Radio/CD Changer, Wiper/Washer System, Anti-Theft Alarm (ATA), Convenience Feature

SUBJECT

Modular Control System (MCS) Malfunctions

SERVICE INFORMATION

If you encounter instances in the above vehicles of intermittent loss of sound, CDC icon flashes on screen or CD not recognized, special attention should be given to the condition of the D2B wiring to eliminate this as a cause of the complaint prior to the replacement of the MCS unit.

The loss of optical signal which results in intermittent D2B ring malfunctions may be due to routing conditions (sharp bends, misalignment) or physical damage to the cable(s) (kinks, pinched). Once the routing conditions have been compromised, signal attenuation may occasionally exceed allowable limits thus causing intermittent failures. The most susceptible areas are:

directly behind the MCS unit,
at the E-call unit and
at the PSE
at the Bose amplifier.

CAUTION: Extra caution must always be exercised during removal and installation of these components or cable may be damaged.

Inspect D2B wiring assuring:

Minimum radius for cable bends does not exceed 25mm.
Connectors are firmly attached and fibers remaining relaxed and tension free
No physical damage (kinks, sharp bends, pinched fibers) exists that will cause permanent loss of signal degradation.

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

As of May 2001 production vehicles, 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. For vehicles produced prior to May 2001, for major repair cases, installation of a new D2B harness is recommended. The harness should be installed in its entirety, following new routing scheme. All unused fibers should be cut off where they exit from the original main wire harness to prevent later confusion.

The following WIS documents should be used:

WIS DOCUMENTS

Document No.	Description
GF82.00-P-4000-01GH	Fiber optic cable position
GF82.00-P-4000-04A	Fiber optic cable function
GF82.00-P-9999A	Digital databus (D2B) survey of system components position/task/design/function