Selector Lever to ECM, CAN-Bus Terminal Resistance, Checking
Selector Lever to ECM, 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 Selector Lever (E313) 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 the Selector Lever (E313).
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. Diagnostic Mode 09 - Read Vehicle Information
Start diagnosis
- Remove the selector mechanism, far enough to gain access to the Selector Lever (E313) electrical harness connector - A -.
- Disconnect the Selector Lever (E313) electrical harness connector - A -.
• The Engine Control Module (ECM) (J623) must remain connected for the following step.
- Using a Multimeter, check the Selector Lever (E313) electrical harness connector terminals 7 to 8 for resistance.
Specified value: 60 to 72 ohms (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 Engine Control Module (ECM) (J623).
If the specified value was obtained:
Checking wiring
If the manufacturers test box is being used. Perform the following step.
- Install the Test Box 105 Pin (VAG1598/31).
If the manufacturers test box is not being used. Perform the following step.
- Remove the Engine Control Module (ECM) (J623). Refer to => [ Engine Control Module, Replacing ] Engine Control Module, Replacing.
- Using a Multimeter, check the Selector Lever (E313) electrical harness connector to the Engine Control Module (ECM) (J623) electrical harness connector T121 for resistance.
Specified value: 1.5 ohms 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:
- 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 Description ] Diagnostic Mode 09 - Read Vehicle Information.
- End diagnosis.
If the DTC does return and no malfunction is detected in the wiring and the voltage supply was OK:
- Replace the Selector Lever (E313).
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 Mode 03 - Read DTC Memory.
2. If necessary, erase the Direct Shift Gearbox (DSG) Mechatronic (J743) memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Diagnostic Mode 04 - Erase DTC Memory.
3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code ] Engine.
- End of diagnosis.