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Connecting to the vehicle's internal CAN network (DB25 cable)

Mercedes Interface Classic Appendix Advanced ⏱ varies 5 steps

Working on some Mercedes components calls for direct access to the internal CAN and LIN networks: on ELV units a direct connection is essential to take them to virgin state, while everything else is done over OBD.

Required licences

  • —

Hardware / cables

  • AVDI
  • DB25 Connector Cable
⚠ WarningWhen connecting modules on the bench watch out for the terminating resistors and where they sit, always work with a stable supply of at least 12V, respect the correct pinouts and follow the wiring diagram exactly.

Procedure

  1. Use the recommended cable for connecting to the internal CAN network: it plugs straight into the AVDI's DB25 port.
  2. Follow the DB25 connector layout: PIN 5 and 6 = Ground, PIN 7 = CAN H, PIN 15 = CAN L.
  3. To identify the wires in the car, remember the rule of thumb for Mercedes colours: on CAN C the green wire is usually CAN LOW and green/white is CAN HIGH; on CAN B brown is normally LOW and brown/red is HIGH.
  4. On the bench, set up a steady supply of at least 12V and check where the resistors are before applying power.
  5. Example pinout for the dual clutch TCM on W117/W176/W246 (EDC15C6): T1-7,8 -> B+; T1-5 -> GND; T2-11 -> CAN-H; T2-12 -> CAN-L; T3-28 -> K-line.

Reference screenshots

Connecting to the vehicle's internal CAN network (DB25 cable) — 1Connecting to the vehicle's internal CAN network (DB25 cable) — 2Connecting to the vehicle's internal CAN network (DB25 cable) — 3Connecting to the vehicle's internal CAN network (DB25 cable) — 4Connecting to the vehicle's internal CAN network (DB25 cable) — 5Connecting to the vehicle's internal CAN network (DB25 cable) — 6
Source: Manuale Mercedes (Offline), cap. 5.17.5.1 (p.122-127) · ⏱ estimated time varies
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