Passat Sedan V6-3.6L (BLV) (2008)
Engine Control Module: Testing and Inspection
CAN-BUS Terminal Resistance, Checking
CAN-Bus Terminal Resistance, Checking
Special tools, testers and auxiliary items required
CAN-Bus malfunction was recognized.
The Motronic Engine Control Module (ECM) J623 fuses OK.
Battery voltage at least 12.5 volts.
All electrical consumers such as, lights and rear window defroster, switched off.
Vehicles with automatic transmission, shift selector lever into position "P" or "N".
A/C switched off.
Ground (GND) connections between engine/transmission/chassis OK.
Ignition switched off.
Perform a preliminary check to verify the customers complaint. See: Testing and Inspection/Scan Tool Testing and Procedures/Preliminary Check
The Motronic Engine Control Module (ECM) 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 Motronic Engine Control Module (ECM) 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 Motronic Engine
Control Module (ECM) J623.
Disconnect the Data Bus On Board Diagnostic Interface T32b electrical harness connector.
NOTE: The Motronic Engine Control Module (ECM) J623 must remain connected for the following step.
Using a Multimeter, check the Data Bus On Board Diagnostic Interface J533 electrical harness connector terminals 19 to 20 for resistance.
Specified value: 60 to 72 Ohms (at approx. 20 degrees C)
If the specified value was not obtained:
Check the wiring connection for an open circuit, short circuit to Battery (+) or Ground (GND).
Check the wiring connection for damage, corrosion, loose or broken terminals.
If necessary, repair the faulty wiring connection.
If no malfunction is found in the wiring: