Introduction:
The diagnostic trouble code (DTC) P1355 indicates a specific issue within the ignition system of an engine, relating to the Integrated Circuit (IC) output signal when cylinder 5 is grounded. This code typically points to a problem with the ignition control module or its associated circuitry, specifically impacting the coil driver circuit for cylinder 5. Understanding the causes and potential solutions for P1355 is crucial for efficient and accurate engine repair.
Table: P1355 Diagnostic Trouble Code Information
| Category | Information | Possible Causes |
|---|---|---|
| Code Definition | IC Output High/Pulse Detected when GND_Cyl. 5 - This signifies that the engine control unit (ECU) has detected an unexpected high voltage or pulse signal from the ignition control module (ICM) output circuit related to cylinder 5 when the cylinder is supposed to be grounded (typically during the spark event). This often implies a fault in the ICM or wiring that prevents proper grounding of the coil. | Faulty Ignition Control Module (ICM): The internal components of the ICM that control the grounding and firing of the coil for cylinder 5 may have failed. This is the most common cause. Wiring Issues: Damaged, corroded, shorted, or open circuits in the wiring harness connecting the ICM to the ECU, the coil for cylinder 5, and the ground circuit. This includes issues with the signal wire, power wire, and ground wire. Faulty Ignition Coil (Cylinder 5): While less common, a shorted or malfunctioning ignition coil can sometimes cause unusual signals that trigger this code. ECU Malfunction (Rare): In very rare cases, the ECU itself may be misinterpreting the signals or have internal faults. Poor Ground Connection: A weak or corroded ground connection to the ICM or the engine block can cause erratic signals. Interference: Electrical interference from other components or wiring can sometimes trigger false readings. Aftermarket Performance Parts: Poorly installed or incompatible aftermarket ignition components (e.g., coils, ICM) can also lead to this code. Loose Connectors: Loose or corroded connectors at the ICM, coil, or ECU can disrupt the signal and trigger the code. * Relay Issues: (If applicable) A faulty ignition relay or a relay related to the ICM power supply can contribute to the problem. (This is less common but should be checked depending on the vehicle's wiring diagram.) |
| Symptoms | Engine misfire on cylinder 5: This is the most noticeable symptom. Rough running engine: The engine may vibrate or run unevenly. Reduced engine power: The misfire can lead to a decrease in overall performance. Poor fuel economy: The engine may be less efficient due to the misfire. Check Engine Light (CEL) is illuminated: This is the primary indicator that a problem exists. Engine stalling: In severe cases, the engine may stall, especially at idle. Hesitation during acceleration: The engine may hesitate or stumble when accelerating. Unusual engine noises: Misfires can sometimes produce popping or sputtering noises. * Failed emissions test: The misfire will likely cause the vehicle to fail an emissions test. |
|
| Troubleshooting | Visual Inspection: Carefully inspect all wiring and connectors related to the ICM, the coil for cylinder 5, and the ground connections. Look for damage, corrosion, or loose connections. Check the Ground Connection: Ensure the ICM and engine block ground connections are clean, tight, and free of corrosion. Test the Ignition Coil: Use a multimeter to test the primary and secondary resistance of the ignition coil for cylinder 5. Compare the readings to the manufacturer's specifications. Test Wiring Continuity: Use a multimeter to check the continuity of the wiring between the ICM, the ECU, and the ignition coil. Look for open circuits or shorts to ground. Check for Shorts to Ground: Use a multimeter to check for shorts to ground in the wiring harness. Inspect the ICM: Visually inspect the ICM for any signs of damage, such as cracks or burn marks. Monitor ICM Signals with a Scan Tool: Use a scan tool that can read live data to monitor the ICM output signals while the engine is running. Look for any unusual patterns or inconsistencies. Perform a Cylinder Balance Test: Use a scan tool to perform a cylinder balance test. This can help identify which cylinder is misfiring. Swap Components (Coil, ICM): If possible, swap the ignition coil or ICM with a known good component from another cylinder. If the problem moves to the other cylinder, this confirms that the component is faulty. (Always consult the vehicle's service manual before swapping components.) Consult a Wiring Diagram: Refer to the vehicle's wiring diagram to understand the circuit layout and identify the correct wires to test. Use a Noid Light: Use a noid light to check for proper pulse activity at the ignition coil connector when the engine is cranking. Check for Proper Voltage at the ICM: Ensure the ICM is receiving the correct voltage from the battery. * Check the Crankshaft Position Sensor (CKP) and Camshaft Position Sensor (CMP): While less likely, a faulty CKP or CMP sensor can sometimes cause misfires. Check their signals with a scan tool. |
Detailed Explanations:
Code Definition:
The P1355 code, "IC Output High/Pulse Detected when GND_Cyl. 5," indicates that the Engine Control Unit (ECU) has detected an unexpected voltage or pulse signal from the Ignition Control Module (ICM) output circuit related to cylinder 5 when the cylinder should be grounded. This is typically the moment when the ignition coil is supposed to fire, creating a spark. The "GND_Cyl. 5" part of the code specifically means that the ECU expected the circuit to be grounded (low voltage) to trigger the coil, but it detected a high voltage or a pulse instead. This suggests a problem preventing the proper grounding of the ignition coil for cylinder 5.
Symptoms:
Several symptoms can accompany the P1355 code. The most common is an engine misfire on cylinder 5. This misfire results in a rough running engine and reduced engine power. You may also notice poor fuel economy and the Check Engine Light (CEL) is illuminated. In more severe cases, the engine might stall, especially at idle, or you could experience hesitation during acceleration. Unusual engine noises, such as popping or sputtering, can also occur. Finally, the vehicle will likely fail an emissions test due to the misfire.
Troubleshooting:
Troubleshooting P1355 requires a systematic approach. Start with a visual inspection of the wiring and connectors related to the ICM, the ignition coil for cylinder 5, and the ground connections. Check the ground connection to ensure it's clean and tight. Test the ignition coil using a multimeter to measure its resistance and compare it to the manufacturer's specifications. Test wiring continuity to identify any open circuits or shorts. Also, check for shorts to ground in the wiring harness. Inspect the ICM for visible damage. If you have a scan tool, monitor ICM signals while the engine is running. A cylinder balance test can also pinpoint the misfiring cylinder. If possible, swap components like the coil or ICM with a known good part. Always consult a wiring diagram to understand the circuit layout. A noid light can be used to check for pulse activity at the ignition coil. Check for proper voltage at the ICM. Finally, in some cases, problems with the Crankshaft Position Sensor (CKP) and Camshaft Position Sensor (CMP) can cause misfires, so check their signals as well.
Faulty Ignition Control Module (ICM):
The Ignition Control Module (ICM) is responsible for controlling the timing and firing of the ignition coils. It receives signals from the ECU and then grounds the appropriate coil to trigger the spark. If the ICM is faulty, it may not be able to properly ground the coil for cylinder 5, leading to the P1355 code. This is often due to internal component failure within the ICM.
Wiring Issues:
Damaged or corroded wiring is a common cause of electrical problems. The wiring harness connecting the ICM, the ECU, and the ignition coil for cylinder 5 is crucial for proper signal transmission. Damage such as frayed wires, corroded connectors, or shorts to ground can disrupt the signal and trigger the P1355 code. It's important to carefully inspect the entire wiring harness and repair any damaged sections.
Faulty Ignition Coil (Cylinder 5):
While less frequent than an ICM failure or wiring issue, a faulty ignition coil can also cause P1355. A shorted or internally damaged coil might create unusual signals that confuse the ECU, leading to the code. Testing the coil's primary and secondary resistance with a multimeter can help determine if it's functioning correctly.
ECU Malfunction (Rare):
In extremely rare cases, the Engine Control Unit (ECU) itself might be the problem. The ECU is responsible for processing signals from various sensors and controlling engine functions, including ignition. If the ECU is misinterpreting signals or has internal faults, it could incorrectly trigger the P1355 code. This is usually diagnosed after ruling out all other possibilities.
Poor Ground Connection:
A good ground connection is essential for proper electrical circuit operation. A weak or corroded ground connection to the ICM or the engine block can cause erratic signals and trigger the P1355 code. Ensure that all ground connections are clean, tight, and free of corrosion.
Interference:
Electrical interference from other components or wiring can sometimes trigger false readings and cause the P1355 code. This is more likely in vehicles with aftermarket electrical modifications. Shielding wires and ensuring proper grounding can help minimize interference.
Aftermarket Performance Parts:
Poorly installed or incompatible aftermarket ignition components, such as coils or ICMs, can also lead to the P1355 code. These parts may not meet the vehicle's electrical specifications, resulting in improper signal transmission. Always use high-quality, compatible parts and ensure they are installed correctly.
Loose Connectors:
Loose or corroded connectors at the ICM, coil, or ECU can disrupt the signal and trigger the code. These connectors should be inspected for damage and corrosion, and properly secured. Applying dielectric grease can help prevent corrosion and ensure a good connection.
Relay Issues:
In some vehicles, a faulty ignition relay or a relay related to the ICM power supply can contribute to the problem. A failing relay might not provide consistent power to the ICM, leading to erratic signals and the P1355 code. Checking the relays and their wiring can help identify this issue. (This is less common and depends on the vehicle's wiring diagram).
Frequently Asked Questions:
What does the P1355 code mean?
P1355 indicates the ECU detected an unexpected high voltage/pulse from the ICM output for cylinder 5 when it should be grounded. This usually points to an ignition system fault.
What is the most common cause of P1355?
The most common cause is a faulty Ignition Control Module (ICM).
Can a bad spark plug cause P1355?
While a bad spark plug can cause misfires, it's less likely to directly trigger P1355. The code specifically relates to the ICM output signal. A spark plug issue may show a different code.
How do I fix a P1355 code?
Troubleshoot by inspecting wiring, testing the coil and ICM, and checking ground connections. Replace faulty components as needed.
Is it safe to drive with a P1355 code?
It's not recommended to drive extensively with P1355 due to potential engine damage from the misfire. Get it checked as soon as possible.
Can a loose gas cap cause P1355? No, a loose gas cap usually triggers EVAP system codes, not ignition-related codes like P1355.
Will replacing the coil pack on cylinder 5 fix the problem? It might, but it's best to test the coil first. The issue could also be the wiring, the ICM, or something else.
Can I clear the P1355 code and see if it comes back? Yes, you can clear the code, but if the underlying issue persists, it will likely return.
How do I test the ignition coil? Use a multimeter to measure the primary and secondary resistance of the coil. Compare the readings to the manufacturer's specifications.
Where is the ICM located? The location of the ICM varies depending on the vehicle. Consult your vehicle's service manual for its exact location.
Conclusion:
The P1355 code indicates a specific issue within the ignition system related to cylinder 5 and the ICM. Proper diagnosis and a systematic approach to troubleshooting are crucial for identifying and resolving the root cause of the problem. Repairing the issue promptly will prevent further engine damage and restore optimal performance.