TCM CAN-Bus Terminal Resistance, Checking

TCM Can-Bus Terminal Resistance, Checking

Special tools, testers and auxiliary items required

• Multimeter.

• Wiring diagram.

Test requirement

• A CAN-Bus malfunction was recognized.

• The Engine Control Module (ECM) ( J623) fuses OK.

• The Transmission Control Module (TCM) (J217) 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.

Function

The 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 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 Engine Control Module (ECM) (J623).

Test procedure

- Perform a preliminary check to verify the customers complaint. Refer to => [ General Diagnosis ] General Diagnosis.

Start diagnosis

- Disconnect the electrical connector in the - direction of the arrow - and remove it from the Transmission Control Module (TCM) (J217).





• The Engine Control Module (ECM) (J623) must remain connected for the following step.

- Using a Multimeter, check the Transmission Control Module (TCM) (J217) electrical harness connector terminals 2 to 6 for resistance.

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

If the specified value was not obtained:

- Using a Multimeter, check the following wiring connections for resistance.





Specified value: 1.5 ohms Max.

If the specified values were not obtained:

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

- Check the wiring connections for damage, corrosion, loose or broken terminals.

- If necessary, repair the faulty wiring connection.

If no malfunction is found in the wiring and the resistance value was not OK:

- Replace the Engine Control Module (ECM) (J623 ). Refer to => [ Engine Control Module, Replacing ] Service and Repair.

- Erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Mode 04 - Erase DTC Memory.

- Perform a road test to verify repair.

If the DTC does not return:

Repair complete, Generate readiness code. Refer to => [ Readiness Code ] Monitors, Trips, Drive Cycles and Readiness Codes.

- End of diagnosis.

If the DTC returns and no malfunction is found in the wiring and the resistance value was OK:

- Replace the Transmission Control Module (TCM) ( J217). Refer to => [ Transmission Control Module, Replacing ] Service and Repair.

Final procedures

1. Check the DTC memory. => [ Diagnostic Mode 03 - Read DTC Memory ] Diagnostic Mode 03 - Read DTC Memory.

2. If necessary, erase DTC memory of the Transmission Control Module (TCM) (J217). => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Mode 04 - Erase DTC Memory.

3. Generate readiness code. => [ Readiness Code ] Monitors, Trips, Drive Cycles and Readiness Codes.

End of diagnosis