2004 Chevrolet Tahoe P0200/P0300/P0308 Misfire Fix: Wiring or PCM Issue?
I recently purchased a 2004 Chevrolet Z71 Tahoe with 90,000 miles. The vehicle was about 200 miles away from my home, so I drove it directly to my residence without any issues at speeds up to 80 mph. However, the very next morning, when I started the car, the check engine light came on and began flashing. A diagnostic scan revealed three fault codes: P0200 (injector circuit open), P0300 (random/multiple cylinder misfire), and P0308 (cylinder 8 misfire). I performed a full tune-up, replacing the spark plugs and wires, fuel filter, fuel pump, oxygen sensors, coil packs, and specifically the #8 injector. Despite these changes, the symptoms persisted. I then took the vehicle to a local dealership for diagnostics—same codes were returned, and they suggested either a wiring issue or a faulty engine control module (PCM). I'm now wondering if others have encountered this exact problem. Any insights or troubleshooting steps would be greatly appreciated. Thanks in advance!
P0200 is likely the root cause, and cylinder 8 should be a key starting point. You’ll need to inspect the injector wiring using a digital volt-ohm meter (DVOM). Check for 12V on the common wire at each injector. Ensure connectors are tight, free of corrosion. Also verify that the signal wire is not grounded or open—test from connector to PCM. Measure injector resistance with a DVOM. Can you perform these checks? Do you need more detailed guidance? Did you use ACDelco spark plugs? Note: The Powertrain Control Module (PCM) controls each fuel injector by grounding its control circuit via a solid-state driver. If the PCM detects an incorrect voltage during this process, it sets a fuel injector control DTC.