P0304 Fault on 1997 Toyota Camry 4-Cylinder: Injector No Voltage, PCM or Wiring Issue?
Hello! I'm experiencing a persistent P0304 diagnostic code on my 1997 Toyota Camry with a 4-cylinder engine. The code indicates a misfire in cylinder #4. I've already replaced the spark plugs, but the code continues to appear. Further testing using a voltmeter revealed that the fuel injector harness for cylinder #4 is not receiving voltage. Given this, I'm wondering whether the issue lies with the Powertrain Control Module (PCM) or if it's more likely a wiring problem. Should I take the vehicle to the dealer for diagnosis, or can I troubleshoot this myself? Any insights would be greatly appreciated.
Each fuel injector should receive a constant 12V supply from the ignition switch, with the other side connected to ground via pulses sent from the ECM. If cylinder #4 is not receiving the 12V power, the issue lies in the wiring harness—this does not indicate a faulty PCM. You should systematically inspect the wiring for damage or loose connections. If the pulse signal from the ECM to the injector is missing, verify that the ground and signal wires are intact by checking for pulses at the corresponding ECM connector pin.