Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
MMI Overview From June 2009
Information Electronics Control Module 1 MMI Overview
The information electronics control module 1 -J794- is a 3rd generation MMI. Depending on the equipment level, the information electronics control module 1 contains the following known control modules from the 2nd generation:
- Front Information Display Control Head Control Module -J523-
- CD player -R89-
- Navigation System with CD Drive Control Module -J401-
- SD Memory Card Reader
- Speech Input Control Module -J507-
- Bluetooth Hands-Free Equipment
- Not Installed
- Internal Hard Drive Disc Storage
- Information Electronics Control Module 1 -J794-
Radio MMI overview
Depending on the equipment level, the radio contain the following known control modules from the 2nd generation:
- Digital Sound System Control Module -J525-
- Radio -R-
- Radio AM/FM Tuner
- Satellite Radio -R146-
- Not Installed
MOST Bus MMI
- Front Information Display Control Head -J685-
- Information Electronics Control Module 1 -J794-
- MOST Bus
- CD Changer -R41-
- Not Installed
- Radio
- Digital Sound System Control Module -J525-
- Data Bus On Board Diagnostic Interface -J533-
- Multimedia Control Head -E380-
Notes on MOST Bus
In addition to the CAN bus systems, the optical data bus system MOST bus is used.
A fiber optic cable is utilized as the connecting cable. Fiber optic cables are routed inside corrugated tubes for protection.
Replace complete fiber optic cable if possible.
Make sure that the face surfaces of the connectors do not become soiled.
If the connectors are disconnected: Attach protective cap for cable connector VAS 6223/9.
Observe the minimum bending radius of 25 mm when routing fiber optic cables. Fiber optic cables must not be pinched or bent.
Repairing fiber optic cables. Refer to FIBER OPTIC CABLE .
Additional information, refer to self study program 286, New data bus systems - LIN, MOST Bluetooth.
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.