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HOMESERVICE MANUALSAUDI1996A4 BASE, STANDARDREPAIR AND DIAGNOSIS (SINGLE PAGE)EXTERNAL PAGESDIFFERENT CARSECTION 61 (ON BOARD DIAGNOSTIC (OBD) - A/T 01L)CAN-BUS, FUNCTIONTWO-WIRE BUS SYSTEM, CHECKINGTWO CONTROL MODULES COMMUNICATE THROUGH A "TWO-WIRE BUS SYSTEM"
1996 Audi A4 Base, Standard

Two control modules communicate through a "two-wire Bus system"

1996 Audi A4 Base, StandardSECTION Two control modules communicate through a "two-wire Bus system"
WARNING: This page does not describe the selected car, but rather 12 other vehicles, including the 2005 Audi allroad, 2004 Audi allroad, 2004 Audi A6, 2003 Audi allroad, and 2003 Audi RS 6. However, it is still accessible from the selected car via links, so may be relevant.
  • Switch off ignition.
  • Disconnect both control modules.
  • Check for open circuit in one of the Bus wires.
    • Fig 1: Schematic - Checking For Open Circuit In One Of The Bus Wires
    G02722652Courtesy of AUDI OF AMERICA, INC.
  • Check for short circuit in Bus wires one against the other.
Fig 2: Schematic - Checking For Short Circuit In Bus Wires One Against Other
G02722653Courtesy of AUDI OF AMERICA, INC.
  • Check for open or short circuit to plus (B+) or to Ground (GND).

    If Bus-wiring is OK:

  • Replace on a trail basis the least expensive control module and the one easiest to get to.
  • If the communication is still not OK, replace the second control module.
Fig 3: Schematic - Checking For Open Or Short Circuit To Plus (B+) Or To Ground (GND)
G02722654Courtesy of AUDI OF AMERICA, INC.
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