Transmission Control Module J217 Can-Bus Terminal Resistance, Checking

The Motronic Engine Control Module (ECM) -J623- 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) -J623-.

Special tools and workshop equipment required 

• Multimeter.
• Wiring diagram.

Test requirement 

• A CAN-Bus malfunction was recognized.
• The Transmission Control Module (TCM) -J217- fuses OK.
• The Motronic Engine Control Module (ECM) -J623- fuses OK.
• Battery voltage at least 12.5 V.
• Ignition switched off.

Test procedure 

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

Procedure 

-- Disconnect the Data Bus On Board Diagnostic Interface -J533- electrical harness connector.

-- Using a Multimeter, check the Data Bus On Board Diagnostic Interface -J533- electrical harness connector terminals 6 to 16 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, loose 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 J217, REPLACING .

If the specified value was obtained:

Checking wiring 

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

-- Install the Adapter F/VAG1598 VAG1598/22.

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

-- Remove the Transmission Control Module (TCM) -J217-. Refer to MOTRONIC ENGINE CONTROL MODULE J623, REPLACING .

-- Using a Multimeter, check the Data Bus On Board Diagnostic Interface -J533- electrical harness connector to the Transmission Control Module (TCM) -J217- electrical harness connector T52 for resistance.

Data Bus On Board Diagnostic Interface -J533- electrical harness connector terminals	Transmission Control Module (TCM) -J217- electrical harness connector T52 terminals or test box sockets
6 (Can_Bus Low)	34
16 (Can_Bus High)	46

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, loose or broken terminals.

-- If necessary, repair the faulty wiring connection.

If no malfunction is found in the wiring:

-- Replace the Data Bus On Board Diagnostic Interface -J533- .

-- Assembly is performed in the reverse of the removal.

Final Procedures 

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

1. Check the DTC memory. Refer to DIAGNOSTIC MODE 03 - READ DTC MEMORY .
2. If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
3. If the DTC memory was erased, generate readiness code. Refer to READINESS CODE .

End of diagnosis.