TCM To ECM Can Bus Terminal Resistance, Checking

Observe all safety precautions: SAFETY PRECAUTIONS

View clean working conditions: CLEAN WORKING CONDITIONS

Prior to repair work, perform a preliminary check to verify the condition. Refer to 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 And Workshop Equipment 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. Refer to the appropriate service information for removal and installation procedures.

-- Disconnect the transmission control module electrical harness connector.

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

-- Repair as necessary.

-- 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 Ω (at approx. 20° C)

If the specified value was not obtained:

Checking wiring

-- Remove the engine control module. Refer to the appropriate service information for removal and installation procedures.

-- 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. Refer to the appropriate service information for removal and installation procedures.

If the specified resistance value was obtained:

-- Remove the engine control module. Refer to the appropriate service information for removal and installation procedures.

-- 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. Refer to the appropriate service information for removal and installation procedures.

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 .
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 .