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.
General information
On vehicles with Telematics, activate Telephone/Telematics Control Module J526 service mode before disconnecting Battery A → Service mode, activating/deactivating .
If the Battery A is reconnected, follow the procedure for disconnecting and connecting the Battery A → - 27 BATTERY, STARTER, GENERATOR, CRUISE CONTROL . Deactivate Telephone/Telematics Control Module J526 service mode → Service mode, activating/deactivating .
Description
BNS 4.0 (Nav IV) navigation system is an enhancement of the established navigation system III.
Important improvements are, e.g. connection to CAN BUS (Infotainment) and dynamic route guidance.
The navigation system receives the information for dynamic route guidance from the Radio R TMC function or via the Telephone Transceiver R36.
The system consists of:
- Function Selector Switch II E272
- Instrument cluster (display unit)
- Navigation System with CD Drive Control Module J401
- Navigation System Antenna R50
Diagnosis is performed using "Guided Fault-Finding".
Repairs on antenna wires → - 97 WIRING .
Repair to CAN bus lines → - 97 WIRING .
NO RELATED
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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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.