Can-Bus Terminal Resistance, Checking: Notes

• Models: A6, A7, A8 use Test Procedure A. Refer to TEST PROCEDURE A (A6, A7, A8) .
• Models A4 / S4, A5 / S5, Q5 use Test Procedure B. Refer to TEST PROCEDURE B (A4 / S4, A5 / S5, Q5) .

General Description 

The Engine Control Module -J623- communicates with other CAN-Bus capable control modules.

The control modules are connected by two data bus wires which are twisted together (CAN_High and CAN_Low), and exchange information (messages). Missing information on the CAN-bus is recognized as a malfunction by the Engine Control Module -J623- and the other control modules connected to the CAN-bus.

Trouble-free operation of the CAN-Bus requires that it have a terminal resistance. This central terminal resistance is located in the Engine Control Module -J623-.

Special tools and workshop equipment required 

• Multimeter.
• Wiring Diagram.

Test requirements 

• Fuses OK.
• Battery voltage OK.
• Switch OFF all electrical and electronic accessories.
• Vehicles with Auto. Transmission, ensure Selector Lever position is in "P".
• Vehicles with Man. Transmission, ensure Shifter Lever position is in "N" with Parking Brake applied.
• Coolant Temperature: ≥ 80° C.
• Observe all safety precautions: SAFETY PRECAUTIONS .
• View clean working conditions: CLEAN WORKING CONDITIONS .
• For Hybrid vehicles refer to: HIGH VOLTAGE SYSTEM GENERAL WARNINGS .