U1593 – Vehicle Communication Bus Malfunction

The ODBII code U1593 indicates a malfunction in the vehicle communication bus, which affects the ability of various electronic control units (ECUs) to communicate with each other.

The severity of ODBII code U1593 is moderate.

Common Causes For: U1592 Lost Communication with the Body Control Module (BCM) – Bus Off.

• Faulty wiring or connectors in the communication bus.
• Malfunctioning control modules.
• Corroded or damaged connectors.
• Short circuits in the communication lines.
• Interference from aftermarket devices.
• Software issues or bugs in the control modules.
• Poor ground connections.
• Low battery voltage or power supply issues.

Common misdiagnosis for U1593 U1593: “Vehicle Communication Bus Malfunction”

• Faulty Engine Control Module (ECM)
• Defective Body Control Module (BCM)
• Wiring issues or shorts in the communication bus
• Bad connectors or terminals
• Malfunctioning sensors
• Issues with the powertrain control module (PCM)
• Problems with the diagnostic port or connectors
• Software or firmware issues in the modules
• Battery or charging system problems
• Grounding issues in the vehicle’s electrical system

Common Troubleshooting Steps

When dealing with OBD-II code U1593, which indicates a “Vehicle Communication Bus Malfunction,” there are several common troubleshooting steps you can follow to diagnose and potentially resolve the issue. Here’s a structured approach:

• Check for Additional Codes: Use an OBD-II scanner to check for any other trouble codes that may be present. Sometimes, multiple codes can provide more context for the issue.
• Inspect the Wiring and Connectors: **Visual Inspection: Look for damaged, frayed, or corroded wiring and connectors related to the communication bus (CAN bus).
• **Connector Integrity: Ensure that all connectors are securely attached and free of corrosion or dirt.
• Check the Battery and Ground Connections: Ensure that the vehicle’s battery is in good condition and fully charged.
• Inspect ground connections for corrosion or looseness, as poor grounding can affect communication.
• Test the Communication Bus: Use a multimeter or an oscilloscope to check the voltage levels on the CAN bus wires. The typical voltage should be around 2.5V when idle.
• Look for any short circuits or open circuits in the communication lines.
• Inspect Modules: Check the various control modules (ECU, TCM, BCM, etc.) for proper operation. A malfunctioning module can disrupt communication.
• If possible, perform a software update on the modules, as outdated software can sometimes cause communication issues.
• Check for Interference: Look for any aftermarket devices or modifications that may interfere with the vehicle’s communication systems, such as alarms, remote starters, or audio systems.
• Perform a Network Test: If available, use a scan tool capable of performing a network test to check the status of the communication bus and identify any modules that are not responding.
• Clear Codes and Test Drive: After performing the above checks and repairs, clear the trouble codes and take the vehicle for a test drive to see if the code returns.
• Consult Technical Service Bulletins (TSBs): Check for any manufacturer-specific TSBs related to U1593 or communication issues for your vehicle make and model.
• Seek Professional Help: If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or technician who specializes in automotive electronics. By following these steps, you should be able to identify and resolve the underlying issue causing the U1593 code.