Experiencing issues connecting your OBD2 reader to your 2012 Infiniti G37? It’s a frustrating situation, especially when you’re trying to diagnose a problem like a no-start condition. If your OBD2 scanner is failing to communicate with the Powertrain Control Module (PCM) in your Infiniti G37, you’re in the right place. This guide will walk you through potential causes and troubleshooting steps to get your diagnostic efforts back on track.
When your OBD2 reader fails to link with your 2012 Infiniti G37’s PCM, it essentially means you’re locked out of accessing crucial diagnostic information. This lack of communication can stem from various issues, ranging from simple fixes to more complex problems within your vehicle’s electronic system. Let’s delve into the symptoms and potential culprits behind this frustrating scenario.
One user reported a series of symptoms in their 2012 Infiniti G37 alongside the OBD2 communication failure. These symptoms paint a clearer picture of the potential underlying issues:
- Check Engine Light (CEL) Not Illuminating During Bulb Check: When you turn the ignition to the “ON” position, the check engine light should briefly illuminate as a bulb check. If this isn’t happening, it indicates a potential problem with the PCM’s basic functions or power supply.
- OBD2 Reader “Cannot Connect”: This is the primary issue – your scan tool is unable to establish a communication link with the PCM.
- Cooling Fans Running with Key “ON”: The cooling fans shouldn’t activate immediately when the key is just in the “ON” position. This unusual fan behavior can suggest PCM malfunction or incorrect sensor readings due to PCM issues.
- No Fuel Pump Prime/No Power to Fuel Pump: A healthy fuel system usually primes the fuel pump for a couple of seconds when the ignition is turned on. The absence of this prime, and confirmed lack of power, points towards a potential PCM control problem or related electrical fault.
- No Spark: If there’s no spark at the spark plugs, the engine won’t start. This is another critical symptom suggesting a potential PCM or ignition system problem.
- NATS (Nissan Anti-Theft System) Light Stays On: A persistently lit NATS light can indicate issues with the immobilizer system, which might be related to PCM communication or security system malfunctions.
These combined symptoms strongly suggest a central issue affecting the PCM or its surrounding electrical circuits. It’s less likely to be a simple sensor failure when multiple critical systems are impacted simultaneously and the OBD2 port is unresponsive.
Possible Causes and Troubleshooting Steps
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Battery and Power Supply: A weak or dying battery can cause a multitude of electrical problems, including PCM communication issues.
- Check Battery Voltage: Ensure your battery is properly charged and holding a charge. A fully charged battery at rest should read around 12.6 volts. Anything below 12.2V could be problematic.
- Inspect Battery Terminals and Cables: Clean and tighten battery terminals. Check for any corrosion or damage to battery cables.
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Fuses and Relays: The PCM and OBD2 port rely on fuses and relays for power.
- Check PCM and OBD2 Fuses: Consult your Infiniti G37’s fuse box diagrams (usually in the owner’s manual or on the fuse box cover) and locate fuses related to the PCM, ECM, and OBD2 port. Inspect these fuses for any signs of being blown. Replace any blown fuses with the correct amperage rating.
- Check PCM and ECM Relays: Similarly, locate and check the relays associated with the PCM and ECM. You can try swapping relays with identical ones (if available) to see if that resolves the issue.
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OBD2 Port Wiring and Connections: A damaged or poorly connected OBD2 port can prevent communication.
- Inspect OBD2 Port: Visually examine the OBD2 port for bent or damaged pins.
- Check OBD2 Port Power and Ground: Use a multimeter to check for power and ground at the OBD2 port. Pin 16 should have battery voltage, and pins 4 and 5 should be ground. If power or ground is missing, trace the wiring back to the fuse box and ground points.
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PCM Grounding: The PCM needs proper grounding to function correctly.
- Locate PCM Ground Points: Identify the PCM ground points (usually bolted to the chassis or engine). Inspect these ground connections for corrosion or looseness. Clean and tighten ground connections as needed.
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PCM or ECU Failure: While less common, the PCM itself can fail.
- Consider PCM Testing: If you’ve exhausted other possibilities, consider having your PCM tested by a specialist diagnostic service. Some shops offer bench testing for ECUs.
- ECU Replacement (with Caution): Attempting to swap the ECU is a complex step. Ensure any replacement ECU is compatible with your 2012 Infiniti G37 (same part number or known compatible equivalent). Note that simply swapping ECUs might not resolve the issue if there’s an underlying wiring or power problem damaging the PCM. Also, immobilizer systems may require programming when replacing the ECU.
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CAN Bus Communication Issues: The OBD2 system relies on the CAN bus network. Problems with the CAN bus wiring or modules can disrupt communication.
- CAN Bus Diagnostics (Advanced): Diagnosing CAN bus issues often requires specialized tools and knowledge. This might involve checking CAN bus wiring integrity and using advanced scan tools to monitor CAN bus signals. This is typically a task for experienced technicians.
Seeking Professional Help
If you’ve gone through these basic troubleshooting steps and are still facing the “2012 Infiniti G37 Obd2 Reader Not Communicating With Pcm” issue, it’s advisable to seek professional help from a qualified automotive technician or a workshop specializing in Infiniti vehicles. Diagnosing complex electrical and PCM problems often requires specialized equipment, diagnostic expertise, and access to vehicle-specific wiring diagrams and repair information. A professional can perform in-depth diagnostics to pinpoint the root cause and implement the necessary repairs, whether it’s a wiring fault, PCM failure, or another underlying issue preventing OBD2 communication and causing your Infiniti G37’s no-start condition.
