CAN-Bus terminal resistance, Transmission Control Module (TCM) J217 to Engine Control Module (ECM) J220 checking, 5 Spd. Automatic Transmission 09A

The Motronic Engine Control Module (ECM) J220 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. The central terminal resistor is located in the Engine Control Module (ECM) J220.

Special tools, testers and auxiliary items required 

• Multimeter.
• Wiring diagram.

Test requirement 

• A CAN-Bus malfunction was recognized.
• The Engine Control Module (ECM) J220 fuses OK.
• Battery voltage at least 12.5 V.
• Ignition switched off.

Removal 

• Remove the wiper arms and wind cowl.

• Disconnect the electrical harness connector in the direction of the arrow.

• Remove the mounting bolts - arrows  -

• Using a Multimeter , check the Transmission Control Module (TCM) J217 electrical harness connector T68a terminals 16 to 15 for resistance.

Specified value: 60 to 72 Ω (at approx. 20 ° 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, lose or broken terminals.
• If necessary, repair the faulty wiring connection.

If no malfunction is found in the wiring:

• Replace the Engine Control Module (ECM) J220. Refer to → Motronic Engine Control Module (ECM) J220 , replacing  .

If the specified value was obtained:

Checking wiring 

If the manufacturers test box is being used. Perform the following step.

• Install the test box Test Box 105 Pin VAG1598/31. Refer to 24 MULTIPORT FUEL INJECTION (MFI) for Engine Code AWD and 24 MULTIPORT FUEL INJECTION (MFI) for Engine Codes AWP and AWW .

If the manufacturers test box is not being used. Perform the following step.

• Remove the Motronic Engine Control Module (ECM) J220. Refer to → Motronic Engine Control Module (ECM) J220 , replacing  .
• Using a Multimeter , check the Transmission Control Module (TCM) J217 electrical harness connector to the Engine Control Module (ECM) J220 electrical harness connector T94 for resistance.

Transmission Control Module (TCM) J217 electrical harness connector terminals	Engine Control Module (ECM) J220 electrical harness connector T121 terminals or test box sockets
16 (Can_Bus Low)	58
15 (Can_Bus High)	60

Specified value: 1.5 Ω Max.

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, lose or broken terminals.
• If necessary, repair the faulty wiring connection.

If no malfunction is found in the wiring:

• Replace the Transmission Control Module (TCM) J217. Refer to → Transmission Control Module (TCM) J217 replacing, 4 Spd. Automatic Transmission 01M  .

Final procedures 

After the repair work, the following work steps must be performed in the following sequence:

1. Check the DTC memory.
2. If necessary, erase DTC memory of the Transmission Control Module (TCM) J217..
3. If the DTC memory was erased, generate readiness code.

End diagnosis