CAN-Bus to Transmission Control Module Checking
CAN-Bus to Transmission Control Module Checking
Special tools, testers and auxiliary items required
• Multimeter.
• Test lamp
• Wiring diagram.
Test requirement
• A CAN Bus malfunction was recognized.
• The Transmission Control Module (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 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 ECM or 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). If multiple loss of communication faults exist between modules, perform the "CAN-Bus Terminal Resistance Checking" diagnostic first.
Test procedure
- Perform a preliminary check to verify the customers complaint. Refer to => [ Preliminary Check ] Preliminary Check
Start diagnosis
- Disconnect the Transmission Control Module (J217) electrical harness connector. The TCM is located under the passenger front seat.
Turn the ignition switch ON.
- Using a multimeter, check the Transmission Control Module (J217) electrical harness connector terminal 46 (CAN Hi) to terminal 34 (CAN Lo) wires for voltage.
Specified value: 0.41 to 0.45 V (at approx. 20° C)
If the specified value was Not obtained:
- Disconnect the Instrument Cluster Module (J285) electrical harness connector. Refer to the Repair Manual.
- Using a multimeter, check the Instrument Cluster Module (J285) electrical harness T32 connector terminals to the Transmission Control Module (J217) electrical harness T52 connector terminals for open circuit, high resistance or short to ground.
Specified value: Circuit resistance less than 1.5 ohms (at approx. 20° C) and no continuity to ground.
If the specified value was Not obtained:
- Check the wiring connection for an open circuit, high resistance or short circuit to voltage or ground.
- Check the wiring connection for damage, corrosion, loose or broken terminals.
- If necessary, repair the faulty wiring connection.
If the specified value was obtained:
- Using a multimeter or test lamp, check the power and ground inputs to the Transmission Control Module (J217). Refer to the Wiring Diagram for pin locations of power and grounds.
If any of the power or grounds were Not present:
- Repair the faulty power or ground circuit. Refer to the Wiring Diagrams.
If the power or grounds were OK:
- Replace the Transmission Control Module (J217). Refer to the Repair Manual.
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 ] Scan Tool Testing and Procedures.
2. If necessary, erase the DTC memory. Refer to => [ Diagnostic Mode 04 - Erase DTC Memory ] Scan Tool Testing and Procedures.
3. If the DTC memory was erased, generate readiness code. Refer to => [ Readiness Code ] Monitors, Trips, Drive Cycles and Readiness Codes.