Transmission Control Systems: Testing and Inspection

TCM to ECM CAN Bus Terminal Resistance, Checking

Observe all safety precautions: => [ Safety Precautions ] Generic Scan Tool

View clean working conditions: => [ Clean Working Conditions ] Clean Working Conditions

Prior to repair work, perform a preliminary check to verify the condition. Refer to => [ Preliminary Check ] Preliminary Check.

Use only gold-plated terminals when servicing any component with gold-plated electrical harness connector terminals.

For wiring diagrams, component locations, and connector views, Refer to the applicable wiring diagram.

Special tools, testers and auxiliary items required

• Multimeter

• Wiring diagram

Test requirement

• A CAN malfunction was recognized

• Battery voltage at least 12.5 volts

• Engine control module fuses OK

• Ignition switched off

Test procedure

- Remove the transmission control module.

- Disconnect the transmission control module electrical harness connector.

- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

- Repair as necessary.

• The ECM must remain connected for the following step. The central terminal resistor is located in the ECM.

- Using a multimeter, check the Direct Shift Gearbox (DSG) Mechatronic (J743) electrical harness connector terminals 10 to 15 for resistance.

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

If the specified value was not obtained:

Checking wiring

- Remove the engine control module.

- Using a multimeter, check each of the CAN bus circuits between the transmission control module and the engine control module. Refer to the applicable wiring diagram.

- Check each CAN circuit for a short to ground, short to voltage, open circuit or high resistance.

- Repair as necessary.

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

- Replace the engine control module.

If the specified resistance value was obtained:

- Remove the engine control module.

- Check each CAN circuit for a short to ground, short to voltage, open circuit or high resistance.

- Repair as necessary.

If no malfunction is found in the wiring:

- Replace the transmission control module.

Final procedures

After 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 ] Diagnostic Modes 01 - 09.

2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Modes 01 - 09.

3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code ] Programming and Relearning.