Can Bus Instrument Cluster To Data Bus OBD Interface, Checking: Function

WARNING: This page is about a different car, the 2014 Volkswagen Passat, 2013 Volkswagen Passat, and 2012 Volkswagen Passat. However, it is still accessible from the selected car via links, so may be relevant.

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 -.

Test procedure

-- Perform a preliminary check to verify the customers complaint. Refer to PRELIMINARY CHECK

Start diagnosis

-- Disconnect the Instrument Cluster Control Module -J285- electrical harness connector.

NOTE:

The Engine Control Module - J623 - must remain connected for the following step.

-- Using a multimeter, Check the Instrument Cluster Control Module -J285- electrical harness connector terminals T32/29 to T32/30 for resistance.

Specified value: 60 to 72 Ω (at approx. 20° C)

If the specified value was not obtained:

-- Check the wiring for a short circuit to Battery (+), or an open circuit.

-- 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:

-- Replace the Engine Control Module - J623 -. Refer to the appropriate service information.

If the specified value was obtained: