Navigating the complexities of your vehicle’s onboard diagnostics system can be daunting, especially when faced with error codes. Among these, the P068A code is a diagnostic trouble code (DTC) that can indicate a significant issue within your vehicle’s powertrain control system. This code, categorized as a generic OBD-II DTC, can affect a wide range of vehicles manufactured from 1996 onwards, including models from Audi, Chrysler, Dodge, Jeep, Ram, and Volkswagen. While the code is broadly applicable, specific diagnostic and repair procedures can differ based on your vehicle’s year, make, model, and powertrain configuration.
Decoding the P068A DTC: ECM/PCM Power Relay De-Energized Performance – Too Early
When your vehicle’s engine control module (ECM) or powertrain control module (PCM) stores a P068A code, it signals a detected malfunction in the process of de-energizing the relay that provides voltage to this critical module. Specifically, the code indicates that the ECM/PCM power relay has de-energized prematurely.
The PCM power relay plays a vital role in safely delivering battery voltage to the necessary circuits within the PCM. This relay, typically a contact-type relay, is activated by a signal from the ignition switch. A crucial aspect of its operation is the controlled de-energization process. This gradual shutdown is essential to prevent voltage spikes that could potentially damage the sensitive electronic components of the controller. These relays commonly feature a five-wire design. One wire provides constant battery voltage, another connects to ground, a third receives a signal from the ignition switch to initiate relay activation, and a fourth supplies voltage to the PCM. The fifth wire is the power relay sense circuit, used by the PCM to monitor the voltage level of the power relay.
If the PCM detects an anomaly during the de-energization of the ECM/PCM power relay, specifically that it’s happening too early, it will store the P068A code. This event may also trigger the malfunction indicator lamp (MIL), illuminating the check engine light on your dashboard.
Alt text: Close-up view of an opened Powertrain Control Module (PCM) highlighting the internal electronic components, relevant to understanding ECM/PCM power relay issues and DTC P068A.
Severity Level of the P068A Code
The P068A trouble code should be considered a serious issue requiring prompt attention. Its presence can lead to significant operational problems, most notably a no-start condition, where the engine fails to start. Furthermore, it can manifest in a range of drivability problems, impacting the vehicle’s overall performance and reliability.
Common Symptoms Associated with the P068A Code
Recognizing the symptoms of a P068A code is crucial for timely diagnosis and repair. The most common symptoms include:
- Delayed Start or No Start Condition: The engine may take longer than usual to start, or fail to start altogether.
- Engine Drivability Issues: This can encompass a broad spectrum of performance problems, such as engine hesitation, stalling, rough idling, or reduced power.
Potential Causes of the P068A Code
Several factors can contribute to the occurrence of a P068A code. Pinpointing the exact cause is essential for effective repair. The common causes include:
- Defective PCM Power Relay: The relay itself may be faulty, failing to operate correctly or de-energizing prematurely.
- Blown Fuse or Fusible Link: A blown fuse or fusible link in the power supply circuit to the PCM power relay can disrupt the relay’s operation.
- Open or Shorted Circuit: Wiring issues, such as an open circuit (break in the wire) or a shorted circuit (unintended connection), between the power relay and the PCM can lead to the P068A code.
Step-by-Step Troubleshooting for the P068A Code
Diagnosing a P068A code requires a systematic approach, utilizing appropriate tools and resources. The following steps provide a comprehensive guide for troubleshooting:
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Gather Necessary Tools and Information: You will need a diagnostic scanner to retrieve codes and live data, and a digital volt/ohmmeter (DVOM) for electrical testing. Crucially, obtain a reliable source of vehicle-specific information. This could be a repair manual or online subscription service providing wiring diagrams, diagnostic flow charts, connector pinouts, component locations, and testing procedures relevant to your vehicle’s year, make, and model.
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Initial Diagnostic Scan: Connect the diagnostic scanner to the vehicle’s diagnostic port. Retrieve all stored trouble codes and freeze frame data. Record this information, as it can be invaluable for diagnosing intermittent issues.
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Clear Codes and Test Drive: After recording the data, clear the stored codes. If possible and safe to do so, test drive the vehicle to see if the P068A code resets or if the PCM enters readiness mode.
- Intermittent Code: If the PCM enters readiness mode and the code doesn’t immediately return, the issue is likely intermittent. Intermittent faults can be more challenging to diagnose as the problem may not be consistently present. The conditions that triggered the code may need to worsen for a definitive diagnosis.
- Persistent Code: If the code resets immediately or fails to clear, and there are no apparent drivability symptoms, the vehicle may seem to operate normally, but the underlying issue needs to be addressed.
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Consult Technical Service Bulletins (TSBs): Review your vehicle information source for any Technical Service Bulletins (TSBs) related to the P068A code, your specific vehicle (year, make, model, and engine), and the symptoms you are experiencing. TSBs often contain valuable diagnostic information and known fixes for common problems.
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Visual Inspection: If the P068A code resets immediately, begin with a thorough visual inspection of the wiring and connectors associated with the PCM power relay and PCM. Look for any signs of damage, such as broken, chafed, or corroded wiring, or loose or damaged connectors. Repair or replace any damaged components as needed.
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Wiring Diagrams and Diagnostic Flow Charts: Utilize your vehicle information source to obtain wiring diagrams, connector face views, connector pin-out charts, and diagnostic flow charts relevant to the PCM power relay circuit. These resources are essential for systematic electrical testing.
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Fuse and Relay Testing: Test all fuses and fusible links in the PCM power relay circuit to ensure they are intact and providing power. Verify that the PCM power supply relay is receiving battery voltage.
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PCM Power Relay De-energizing Parameters: Refer to your vehicle-specific information for the correct PCM power relay de-energizing parameters. These specifications are crucial for accurate diagnosis in the following steps.
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Power Relay Input Voltage Testing: If constant (or switched, as per your vehicle’s system) voltage is not present at the power relay connector, trace the circuit back to its power source (fuse or relay). Repair or replace any defective fuses or fusible links.
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Power Relay Output Testing: If the power relay is receiving proper input voltage and ground, use your DVOM to test the relay’s output performance at the appropriate connector pins. Compare your readings to the specified parameters. If the output voltage is inadequate or absent, suspect a defective power relay and replace it.
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PCM Connector Voltage Testing: If the power relay output voltage is within specifications, test the corresponding relay output circuits at the PCM connector itself.
- Voltage Signal Present at PCM: If a proper voltage signal is present at the PCM connector but the P068A code persists, suspect a fault within the PCM itself. This could be due to a defective PCM or a PCM programming error.
- No Voltage Signal at PCM: If there is no appropriate PCM power relay output voltage signal detected at the PCM connector, suspect an open or shorted circuit in the wiring between the PCM power relay and the PCM. Carefully inspect and test the wiring for continuity and shorts.
Important Note: When testing fuses and fusible links, it’s crucial to test them under load (while the circuit is active) to avoid misdiagnosis. A fuse may appear good when tested without a load, but fail when current flows through it.
Need Further Assistance with P068A?
For more in-depth help with diagnosing and resolving the P068A trouble code, we encourage you to post your question in our free car repair forums. Our community of experienced technicians and enthusiasts can provide further guidance and support to help you resolve your vehicle’s issue.
