S4 V8-4.2L (BHF) (2004)
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Information Bus: Component Tests and General Diagnostics
Terminal Resistance For CAN-Bus, Checking
Terminal Resistance For CAN-Bus, Checking
The Engine Control Module (ECM) communicates with all databus-capable control modules via a CAN databus.
These databus-capable control modules are connected via two data bus wires which are twisted together (CAN_High and CAN_Low), and exchange
information (messages). Missing information on the databus is recognized as a malfunction and stored.
Trouble-free operation of the CAN-bus requires that it have a terminal resistance. This central terminal resistor is located in the Engine Control Module
(ECM).
Recommended special tools and equipment
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V.A.G 1526A multimeter
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V.A.G 1594A connector test kit
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V.A.G 1598/31 test box
Test requirement:
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Ignition switched off.
Test sequence
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Connect test box to the Engine Control Module (ECM); wiring harness is not connected. See: Testing and Inspection/Reading and Clearing
Diagnostic Trouble Codes/Scan Tool Connecting/Test Box, Connecting For Wiring and Component Test
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Check the central termination resistor in the Engine Control Module (ECM):
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Connect multimeter between terminal 58 and 60 of test box for resistance measurement.
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Specified value: 60 to 72 Ohms
If specification is exceeded or not met:
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Replace Engine Control Module (ECM).