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
-
Multimeter.
-
Wiring diagram.
Test requirement
-
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.
Test procedure
-
Perform a preliminary check to verify the customers complaint. See: Testing and Inspection/Scan Tool Testing and Procedures/Preliminary Check
Start diagnosis
Function
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.
Procedure
-
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: