What Does It Mean?
This is a generic powertrain diagnostic trouble code (DTC), meaning it covers all makes/models from 1996 onward. However, specific troubleshooting steps vary by vehicle.
This code indicates a malfunction in the wiring link between the Electronic Control Module (ECM) and one of its supported control modules. The On-Board Diagnostic (OBD) trouble code P0600 is generic by design and applies to all computer-controlled vehicles.
Explanation of OBD Code P0600
Your vehicle’s ECM or Powertrain Control Module (PCM) has lost control over one or more actuator modules. Most vehicles have up to 18 actuators controlled by the main ECM. It does this via a Controller Area Network (CAN Bus Automotive Network), which is a series of wiring harnesses running from the ECM to the controllers.
The controllers operated by the ECM, called modules, control the majority of your vehicle’s functions. Code P0600 is set when the ECM recognizes a loss of communication and control over one or more of these modules for eight consecutive ignition cycles.
ECM and Associated Control Modules
Here is a list of the main control modules operated by the ECM:
Fuel injection system
SRS ignition system
Variable camshaft timing
Turbocharger
Emission systems
Air conditioning
Transmission shift points
Body control
ABS brakes
Cruise control
Anti-theft system
Sunroof and seat position
Power windows
Traction control systems
Proximity alerts
These are just a few, not to mention all the computer-controlled options available today.
Symptoms
This is a code often misdiagnosed as it can cause misleading symptoms. Always keep in mind that code P0600 indicates a communication failure. For example—a failure in the ignition system or a faulty fuel injector can cause a misfire.
An inexperienced technician might start by trying to diagnose the affected system rather than the communication loss. If the ECM is not controlling the ignition control module or not grounding the fuel injector, a misfire will occur.
This is not a fault with the system itself, but with the control of the system. Depending on the location of the failure, the following symptoms may be present:
Check engine light on accompanied by an additional code,
ABS light illuminated,
Transmission light on (vehicle may not move properly),
Significant drop in fuel economy,
Drivability issues such as stalling at idle, rough running, and poor acceleration, or
Problems with a particular system indicating a possible loss of communication in that area.
Potential Causes
Experience has shown that a poor connection or a failing ECM driver is the primary cause of this code. For the most part, the ECM serves as the ground to control these components and modules rather than providing them with power.
A loose or corroded connector is more likely than a frayed or broken wire between the two devices. Poor grounds are another plausible cause. The ECM, as well as the activation module, require a good ground to function.
The wiring harness or bus line may be faulty and have a short to ground or an open wire.
Diagnostic and Repair Procedures
The best advice regarding diagnosing and repairing this particular code is to entrust the vehicle to a professional technician with an Autohex or Tech II diagnostic computer.
If you disconnect the ECM or associated wiring and then probe the terminals, your bank account could suffer extreme consequences.
Most vehicles require a memory saver to be installed before disconnecting the battery to preserve the ECM’s memory. If the ECM loses its memory due to power loss, the vehicle will not start until it is reprogrammed at the dealership.
Testing the wiring must be done systematically using the wiring diagram and pin values. If you probe the wrong terminal, the ECM and/or its associated module will be destroyed.
A skilled technician will program your vehicle’s information into their Autohex or similar diagnostic computer in preparation for diagnosing code P0600. They will then start the vehicle and monitor all systems in real time. The tool displays pin values and operating modules and indicates any anomalies. It is an essential tool for diagnosing wiring or computer issues without risking damage to components.
If you’re lucky, symptoms or an additional code following the P0600 code will point you to the system in question that is experiencing the communication failure.
When identifying the system through symptoms or an additional code, check the connections for anomalies such as loose or corroded terminals. A service manual with wiring diagrams, pin values, connector locations, precautions, and procedures is imperative.