Body Control System
DTC U0073: Control Module Communication Bus OFFWiring Diagram:
Circuit Description
The aim of the CAN network is to allow exchange of information between the Engine Control Module (ECM) and the Transaxle Control Module (TCM) numerous data are sent from to select the better gear. On the other side TCM sends information to the ECM (vehicle speed, transaxle oil temperature, current gear value, 0). The can network is conceived with an unshielded twisted pair of wires in order to reduce effects of engine control interfaces. The TCM is an electronic unit which selects the correct gear for automatic transaxle depending of several parameters. In order to achieved these functions, the TCM receives and sends message to the ECM following a normalized protocol CAN V2.0A.
Conditions for Setting the DTC
- No valid communication by the ECM.
- Ignition ON.
Action Taken When the DTC Sets
- The Malfunction Indicator Lamp (MIL) will illuminate.
- The ECM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records buffers.
- A history DTC is stored.
Conditions for Clearing the MIL/DTC
- The MIL will turn OFF at the end of 3 consecutive ignition cycles in which the diagnostic runs without a fault.
- A history DTC will clear after 40 warm up cycles without a fault.
- Using the scan tool can clear DTC(s).
Diagnostic Aids
An Intermittent problem may be caused by a poor connection, rubbed through wire insulation, or wire that is broken inside the insulation. Any circuitry, that is suspected as causing the complaint, should be thoroughly checked for the following conditions.
- Backed-out terminals
- Improper mating
- Broken locks
- Improperly formed
- Damaged terminals
- Poor terminals to wire connection
- Physical damage to the wiring harness
Step 1 - 3:
Step 4 - 9:
DTC Troubleshooting