Technical Description of OBD-II Trouble Code
Generic: Malfunction in Serial Communication Link
Chrysler: Fault in PCM, SPI Communications Conditions
GM: Conditions of Loss of Serial Communication Link
Infiniti: Malfunction in AT communication circuit
Nissan: Malfunction in ECM/TCM communication
What does that signify?
This is a generic diagnostic trouble code (DTC) for powertrain, which applies to all makes/models from 1996 onwards. However, the specific troubleshooting steps will vary depending on the vehicle.
This code indicates a malfunction in the wiring link between the electronic control module (ECM) and one of its supporting control modules. The OBD trouble code P0600 is designed to be generic and covers 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 around 18 actuators that are controlled by the primary ECM. This control is achieved through a controller area network (Can Bus Automotive Network), which consists of wiring harnesses connecting the ECM to the controllers.
The modules controlled by the ECM, known as modules, handle the majority of your vehicle’s functions. The code P0600 is set when the ECM detects a loss of communication and control over one or more of these modules for eight consecutive starts.
ECM and associated control modules
This is a list of the primary control modules operated by the ECM:
These are just a few examples, not to mention all the available computer controlled options available today.
Symptoms
This code is often misdiagnosed because it can cause deceptive symptoms. It is important to remember that the code P0600 indicates a communication failure. For example, a failure in the ignition system or a failed fuel injector can cause a misfire.
An inexperienced technician may initially try to diagnose the affected system instead of focusing on the loss of communication. If the ECM is not controlling the ignition control module or grounding the fuel injector, a misfire will occur.
This is not a fault with the system itself, but rather with the control of the system. Depending on the location of the failure, the following symptoms may be present:
Potential Causes
Experience has shown that a poor connection or failed ECM driver is the main cause of this code. In most cases, the ECM acts as a ground to control these components and modules rather than supplying power to them.
A loose or corroded connector is more likely than a frayed or broken wire between the two devices. Poor grounds are another possible cause. Both the ECM and the activator module require a good ground to operate.
The wiring harness or Can Bus may be defective and have a short to ground or an open wire.
Diagnostic and Repair Procedures
The best advice for diagnosing and repairing this particular code is to take the vehicle to a professional technician who has an Autohex or Tech II diagnostic computer.
If you unplug the ECM or associated wiring and then probe the terminals, it could have severe consequences for your bank account.
Most vehicles need to have a memory saver installed before disconnecting the battery to retain the ECM’s memory. If the ECM loses its memory due to lack of power, the vehicle will not start until it is reprogrammed at the dealer.
Probing 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 damaged.
A competent technician will program your vehicle’s information into his Autohex or similar diagnostic computer in preparation for diagnosing the P0600 code. They will then start the vehicle and monitor all the systems in real time. The tool displays the pin values and modules in operation, indicating any abnormalities. It is an essential tool for diagnosing wiring or computer-related problems without risking damage to any components.
If you’re lucky, symptoms or an additional code following code P0600 will guide you to the system experiencing the communication failure.
Once you have identified the system through symptoms or an additional code, check the connections for any discrepancies such as loose or corroded terminals. A service manual with wiring diagrams, pin values, connector locations, precautions, and procedures is essential.
