The P1389 trouble code is a diagnostic trouble code (DTC) that indicates a malfunction related to the Auto Shutdown (ASD) relay in a vehicle’s powertrain management system. Specifically, it signifies that the Powertrain Control Module (PCM) is not detecting the expected output voltage from the ASD relay when it is energized. This can lead to various issues, including engine stalling or failure to start, making it crucial for vehicle owners and DIY mechanics to understand and address this code effectively.
| P1389 Code Meaning | P1389 Code Common Causes |
|---|---|
| No ASD Relay Output Voltage At PCM | Faulty ASD relay preventing voltage supply |
| PCM Not Detecting Voltage from ASD Relay | Open or shorted ASD relay harness |
| Intermittent Voltage Loss at PCM | Poor electrical connections in the ASD circuit |
| Potential PCM Malfunction | Faulty Powertrain Control Module |
Symptoms of P1389 Code
When a vehicle triggers the P1389 code, several symptoms may manifest, indicating an underlying issue:
- Engine Cranking but Not Starting: The most common symptom is the engine cranking without starting, which can be frustrating for drivers.
- Intermittent Stalling: The vehicle may run for a while and then suddenly stall, especially under load or during acceleration.
- Check Engine Light: The illumination of the check engine light on the dashboard is a direct indication of this trouble code.
- Poor Engine Performance: Drivers may experience a decrease in power, rough idling, or hesitation during acceleration.
Understanding these symptoms can help diagnose the issue more effectively.
Technical Explanation of P1389 Code
The P1389 code is primarily related to the Auto Shutdown (ASD) relay, which plays a critical role in powering essential components of the engine management system. The ASD relay controls power to several components, including:
- Fuel injectors
- Ignition coils
- Oxygen sensors
When the PCM energizes the ASD relay, it expects to receive voltage back from the relay. If this voltage is not detected, it triggers the P1389 code. This could be due to several factors including:
- A faulty ASD relay that fails to provide output voltage.
- Damaged wiring or connectors between the ASD relay and PCM.
- A malfunctioning PCM that cannot process the signal correctly.
Step-by-Step Diagnosis of P1389 Code
Diagnosing the P1389 code involves a systematic approach:
- Initial Scan: Use an OBD-II scanner to confirm the presence of the P1389 code and check for any additional codes that may provide further insights.
- Inspect ASD Relay: Locate and visually inspect the ASD relay for any signs of damage or corrosion.
- Check Fuses: Ensure that all relevant fuses are intact and functioning properly.
- Test Voltage at Relay:
- With the ignition on (engine off), check for voltage at cavity No. 30 of the ASD relay using a multimeter.
- If voltage is present but not reaching the PCM, there may be an issue with wiring or connectors.
- Inspect Wiring Harness: Examine the wiring harness between the ASD relay and PCM for any signs of wear, damage, or shorts.
- Relay Swap Test: If possible, swap the ASD relay with another similar relay in the power distribution center (PDC) to rule out relay failure.
- Check PCM Grounds: Ensure that all ground connections for the PCM are secure and free from corrosion.
- Final Testing: After repairs or replacements, clear any codes with the scanner and test drive the vehicle to ensure proper operation.
Solution Methods for P1389 Code
To resolve a P1389 code issue effectively, consider these methods:
- Replace Faulty ASD Relay: If testing indicates that the ASD relay is faulty, replacing it is often a straightforward solution.
- Repair Wiring Issues: If damaged wiring or connectors are found during inspection, repair or replace them as necessary to restore proper electrical flow.
- Replace PCM if Necessary: In cases where all other components are functioning correctly but issues persist, consider replacing the PCM as a last resort.
Cost Estimates
The cost associated with diagnosing and repairing a P1389 code can vary widely based on several factors:
- Diagnostic Fees: Expect to pay between $100-$150 for professional diagnostic services if using a mechanic.
- Parts Replacement Costs:
- ASD Relay: $20-$50
- Wiring Repairs: $50-$200 depending on complexity
- PCM Replacement: $300-$800 (including labor)
Warnings and Recommendations
When dealing with electrical issues like those indicated by a P1389 code:
- Safety First: Always disconnect the battery before working on electrical components to prevent shocks or shorts.
- Consult Professionals When Needed: If you are unsure about any steps in diagnosing or repairing this issue, consult with an ASE-certified technician to avoid costly mistakes.
Closing Paragraph
The P1389 trouble code indicates significant issues within your vehicle’s electrical system related to the Auto Shutdown relay. Understanding its symptoms and causes allows vehicle owners and DIY mechanics to take informed steps toward diagnosis and repair. By following systematic troubleshooting methods and seeking professional help when necessary, you can restore your vehicle’s performance and reliability effectively.
Frequently Asked Questions About P1389
- What does error code P1389 mean?
It indicates that there is no output voltage from the Auto Shutdown (ASD) relay detected by the Powertrain Control Module (PCM). - Can I drive my car with a P1389 code?
While it may be possible to drive temporarily, doing so could lead to stalling or failure to start; it’s advisable to address it promptly. - How do I reset a P1389 code?
You can reset it by disconnecting your battery for a few minutes or using an OBD-II scanner to clear codes after repairs. - What are common symptoms of a bad ASD relay?
Common symptoms include engine cranking without starting, intermittent stalling, and poor engine performance. - Is replacing an ASD relay difficult?
Replacing an ASD relay is generally straightforward and can often be done by DIY mechanics with basic tools. - What should I do if my car won’t start after replacing parts?
If your car still won’t start after replacing parts related to P1389, further diagnosis may be needed; consider consulting a professional. - How much does it cost to fix a P1389 code?
The total cost can range from $100 for diagnostics up to $800 for parts replacement depending on what needs fixing. - Can other codes accompany P1389?
Yes, it’s common for other codes related to ignition or fuel systems to appear alongside P1389; these should also be diagnosed.